diff --git a/src/api/api_model.cpp b/src/api/api_model.cpp
index c7347f299..664022f2e 100644
--- a/src/api/api_model.cpp
+++ b/src/api/api_model.cpp
@@ -472,7 +472,7 @@ extern "C" {
             model_smt2_pp(buffer, mk_c(c)->m(), *(to_model_ref(m)), 0);
             // Hack for removing the trailing '\n'
             result = buffer.str();
-            if (result.size() != 0)
+            if (!result.empty())
                 result.resize(result.size()-1);
         }
         else {
diff --git a/src/ast/ast_smt_pp.cpp b/src/ast/ast_smt_pp.cpp
index 0def08094..2490e0314 100644
--- a/src/ast/ast_smt_pp.cpp
+++ b/src/ast/ast_smt_pp.cpp
@@ -399,12 +399,12 @@ class smt_printer {
             pp_marked_expr(n->get_arg(0));
             m_out << ") (_ bv1 1))";
         }
-        else if (m_manager.is_label(n, pos, names) && names.size() >= 1) {
+        else if (m_manager.is_label(n, pos, names) && !names.empty()) {
             m_out << "(! ";
             pp_marked_expr(n->get_arg(0));
             m_out << (pos?":lblpos":":lblneg") << " " << m_renaming.get_symbol(names[0], false) << ")";            
         }
-        else if (m_manager.is_label_lit(n, names) && names.size() >= 1) {
+        else if (m_manager.is_label_lit(n, names) && !names.empty()) {
             m_out << "(! true :lblpos " << m_renaming.get_symbol(names[0], false) << ")";
         }
         else if (num_args == 0) {
@@ -952,7 +952,7 @@ void ast_smt_pp::display_smt2(std::ostream& strm, expr* n) {
     if (m_logic != symbol::null && m_logic != symbol("")) {
         strm << "(set-logic " << m_logic << ")\n";
     }
-    if (m_attributes.size() > 0) {
+    if (!m_attributes.empty()) {
         strm << "; " << m_attributes.c_str();
     }
 
diff --git a/src/ast/expr2polynomial.cpp b/src/ast/expr2polynomial.cpp
index 280d7487a..82bace428 100644
--- a/src/ast/expr2polynomial.cpp
+++ b/src/ast/expr2polynomial.cpp
@@ -436,7 +436,7 @@ struct expr2polynomial::imp {
                         margs.push_back(t);
                 }
             }
-            if (margs.size() == 0) {
+            if (margs.empty()) {
                 args.push_back(m_autil.mk_numeral(rational(1), is_int));
             }
             else if (margs.size() == 1) {
@@ -447,7 +447,7 @@ struct expr2polynomial::imp {
             }
         }
 
-        if (args.size() == 0) {
+        if (args.empty()) {
             r = m_autil.mk_numeral(rational(0), is_int);
         }
         else if (args.size() == 1) {
diff --git a/src/ast/proofs/proof_utils.cpp b/src/ast/proofs/proof_utils.cpp
index 5483a9ea0..5c37c3794 100644
--- a/src/ast/proofs/proof_utils.cpp
+++ b/src/ast/proofs/proof_utils.cpp
@@ -238,7 +238,7 @@ class reduce_hypotheses {
         { args.push_back(fact); }
 
 
-        if (args.size() == 0) { return pf; }
+        if (args.empty()) { return pf; }
         else if (args.size() == 1) {
             lemma = args.get(0);
         } else {
diff --git a/src/cmd_context/basic_cmds.cpp b/src/cmd_context/basic_cmds.cpp
index ea5994ece..981698db7 100644
--- a/src/cmd_context/basic_cmds.cpp
+++ b/src/cmd_context/basic_cmds.cpp
@@ -137,7 +137,7 @@ ATOMIC_CMD(get_assignment_cmd, "get-assignment", "retrieve assignment", {
         symbol const & name = kv.m_key;
         macro_decls const & _m    = kv.m_value;
         for (auto md : _m) {
-            if (md.m_domain.size() == 0 && ctx.m().is_bool(md.m_body)) {
+            if (md.m_domain.empty() && ctx.m().is_bool(md.m_body)) {
                 model::scoped_model_completion _scm(*m, true);
                 expr_ref val = (*m)(md.m_body);
                 if (ctx.m().is_true(val) || ctx.m().is_false(val)) {
diff --git a/src/cmd_context/cmd_context.cpp b/src/cmd_context/cmd_context.cpp
index fb81c673e..8675365c9 100644
--- a/src/cmd_context/cmd_context.cpp
+++ b/src/cmd_context/cmd_context.cpp
@@ -2108,7 +2108,7 @@ void cmd_context::dt_eh::operator()(sort * dt, pdecl* pd) {
             m_owner.insert(a);
         }
     }
-    if (m_owner.m_scopes.size() > 0) {
+    if (!m_owner.m_scopes.empty()) {
         m_owner.pm().inc_ref(pd);
         m_owner.m_psort_inst_stack.push_back(pd);
     }
diff --git a/src/cmd_context/tactic_cmds.cpp b/src/cmd_context/tactic_cmds.cpp
index a89e76edb..7fdca8cdd 100644
--- a/src/cmd_context/tactic_cmds.cpp
+++ b/src/cmd_context/tactic_cmds.cpp
@@ -224,7 +224,7 @@ public:
                     ctx.display_sat_result(r);
                     result->set_status(r);
                     if (r == l_undef) {
-                        if (reason_unknown != "") {
+                        if (!reason_unknown.empty()) {
                             result->m_unknown = reason_unknown;
                             // ctx.diagnostic_stream() << "\"" << escaped(reason_unknown.c_str(), true) << "\"" << std::endl;
                         }
diff --git a/src/math/polynomial/polynomial.cpp b/src/math/polynomial/polynomial.cpp
index aec901f61..8f7f08c7f 100644
--- a/src/math/polynomial/polynomial.cpp
+++ b/src/math/polynomial/polynomial.cpp
@@ -67,7 +67,7 @@ namespace polynomial {
         bool first = true;
         out << "[";
         for (unsigned i = 0; i < m_var2degree.size(); ++ i) {
-            if (m_var2degree.size() > 0) {
+            if (!m_var2degree.empty()) {
                 if (!first) {
                     out << ",";
                 }
diff --git a/src/math/polynomial/upolynomial.cpp b/src/math/polynomial/upolynomial.cpp
index 39bdb6812..5a7ed0dc1 100644
--- a/src/math/polynomial/upolynomial.cpp
+++ b/src/math/polynomial/upolynomial.cpp
@@ -96,7 +96,7 @@ namespace upolynomial {
 
     void core_manager::factors::display(std::ostream & out) const {
         out << nm().to_string(m_constant);
-        if (m_factors.size() > 0) {
+        if (!m_factors.empty()) {
             for (unsigned i = 0; i < m_factors.size(); ++ i) {
                 out << " * (";
                 m_upm.display(out, m_factors[i]);
diff --git a/src/math/polynomial/upolynomial_factorization.cpp b/src/math/polynomial/upolynomial_factorization.cpp
index 5d9d3f1f1..57106e22d 100644
--- a/src/math/polynomial/upolynomial_factorization.cpp
+++ b/src/math/polynomial/upolynomial_factorization.cpp
@@ -532,7 +532,7 @@ bool check_hansel_lift(z_manager & upm, numeral_vector const & C,
     upm.mul(A_lifted.size(), A_lifted.c_ptr(), B_lifted.size(), B_lifted.c_ptr(), test1);
     upm.sub(C.size(), C.c_ptr(), test1.size(), test1.c_ptr(), test1);
     to_zp_manager(br_upm, test1);
-    if (test1.size() != 0) {
+    if (!test1.empty()) {
         TRACE("polynomial::factorization::bughunt", 
             tout << "sage: R.<x> = ZZ['x']" << endl;
             tout << "sage: A = "; upm.display(tout, A); tout << endl;
diff --git a/src/math/polynomial/upolynomial_factorization_int.h b/src/math/polynomial/upolynomial_factorization_int.h
index 10bfb4d8b..816914545 100644
--- a/src/math/polynomial/upolynomial_factorization_int.h
+++ b/src/math/polynomial/upolynomial_factorization_int.h
@@ -401,7 +401,7 @@ namespace upolynomial {
                 } else {   
                     if (selection_i >= m_current.size() || (int) current < m_current[selection_i]) {
                         SASSERT(m_factors.get_degree(current) == 1);
-                        if (out.size() == 0) {
+                        if (out.empty()) {
                             upm.set(m_factors[current].size(), m_factors[current].c_ptr(), out);
                         } else {
                             upm.mul(out.size(), out.c_ptr(), m_factors[current].size(), m_factors[current].c_ptr(), out);
diff --git a/src/math/realclosure/realclosure.cpp b/src/math/realclosure/realclosure.cpp
index 77623a2df..0bc3b43d3 100644
--- a/src/math/realclosure/realclosure.cpp
+++ b/src/math/realclosure/realclosure.cpp
@@ -3466,11 +3466,11 @@ namespace realclosure {
         // ---------------------------------
 
         bool is_monic(value_ref_buffer const & p) {
-            return p.size() > 0 && is_rational_one(p[p.size() - 1]);
+            return !p.empty() && is_rational_one(p[p.size() - 1]);
         }
 
         bool is_monic(polynomial const & p) {
-            return p.size() > 0 && is_rational_one(p[p.size() - 1]);
+            return !p.empty() && is_rational_one(p[p.size() - 1]);
         }
 
         /**
diff --git a/src/model/model.cpp b/src/model/model.cpp
index 2efc39db8..86ff64ea3 100644
--- a/src/model/model.cpp
+++ b/src/model/model.cpp
@@ -85,7 +85,7 @@ struct model::value_proc : public some_value_proc {
     expr * operator()(sort * s) override {
         ptr_vector<expr> * u = nullptr;
         if (m_model.m_usort2universe.find(s, u)) {
-            if (u->size() > 0)
+            if (!u->empty())
                 return u->get(0);
         }
         return nullptr;
diff --git a/src/muz/base/dl_rule_set.h b/src/muz/base/dl_rule_set.h
index e870e369c..633676ec7 100644
--- a/src/muz/base/dl_rule_set.h
+++ b/src/muz/base/dl_rule_set.h
@@ -230,7 +230,7 @@ namespace datalog {
         bool is_closed() const { return m_stratifier != 0; }
 
         unsigned get_num_rules() const { return m_rules.size(); }
-        bool empty() const { return m_rules.size() == 0; }
+        bool empty() const { return m_rules.empty(); }
 
         rule * get_rule(unsigned i) const { return m_rules[i]; }
         rule * last() const { return m_rules[m_rules.size()-1]; }
diff --git a/src/muz/bmc/dl_bmc_engine.cpp b/src/muz/bmc/dl_bmc_engine.cpp
index f804a239a..b03a9aab1 100644
--- a/src/muz/bmc/dl_bmc_engine.cpp
+++ b/src/muz/bmc/dl_bmc_engine.cpp
@@ -986,7 +986,7 @@ namespace datalog {
                 m_sort2pred.insert(new_sorts[i].get(), it->m_key);
                 m_pinned.push_back(new_sorts[i].get());
             }
-            if (new_sorts.size() > 0) {
+            if (!new_sorts.empty()) {
                 TRACE("bmc", dtu.display_datatype(new_sorts[0].get(), tout););
             }
             del_datatype_decls(dts.size(), dts.c_ptr());
diff --git a/src/muz/fp/datalog_parser.cpp b/src/muz/fp/datalog_parser.cpp
index 1cc85e6cd..cc0a60335 100644
--- a/src/muz/fp/datalog_parser.cpp
+++ b/src/muz/fp/datalog_parser.cpp
@@ -1057,7 +1057,7 @@ protected:
             line.push_back(ch);
             ch = strm.get();
         }
-        return line.size() > 0;
+        return !line.empty();
     }
 
     void add_rule(app* head, unsigned sz, app* const* body, const bool * is_neg) {
diff --git a/src/muz/rel/dl_finite_product_relation.cpp b/src/muz/rel/dl_finite_product_relation.cpp
index 0b1fbc840..ccb4584f7 100644
--- a/src/muz/rel/dl_finite_product_relation.cpp
+++ b/src/muz/rel/dl_finite_product_relation.cpp
@@ -487,7 +487,7 @@ namespace datalog {
 
             res->init(*res_table, joined_orelations, true);
 
-            if(m_tr_table_joined_cols.size()) {
+            if(!m_tr_table_joined_cols.empty()) {
                 //There were some shared variables between the table and the relation part.
                 //We enforce those equalities here.
                 if(!m_filter_tr_identities) {
diff --git a/src/muz/rel/dl_sieve_relation.h b/src/muz/rel/dl_sieve_relation.h
index 5f20cecb4..2d89faa5b 100644
--- a/src/muz/rel/dl_sieve_relation.h
+++ b/src/muz/rel/dl_sieve_relation.h
@@ -170,7 +170,7 @@ namespace datalog {
             SASSERT(is_inner_col(idx));
             return m_sig2inner[idx];
         }
-        bool no_sieved_columns() const { return m_ignored_cols.size()==0; }
+        bool no_sieved_columns() const { return m_ignored_cols.empty(); }
         bool no_inner_columns() const { return m_ignored_cols.size()==get_signature().size(); }
 
         relation_base & get_inner() { return *m_inner; }
diff --git a/src/muz/rel/dl_sparse_table.cpp b/src/muz/rel/dl_sparse_table.cpp
index a51fbf3b1..db62d14d5 100644
--- a/src/muz/rel/dl_sparse_table.cpp
+++ b/src/muz/rel/dl_sparse_table.cpp
@@ -1216,7 +1216,7 @@ namespace datalog {
            
             verbose_action  _va("filter_by_negation");
 
-            if (m_cols1.size() == 0) {
+            if (m_cols1.empty()) {
                 if (!neg.empty()) {
                     tgt.reset();
                 }
diff --git a/src/muz/rel/dl_sparse_table.h b/src/muz/rel/dl_sparse_table.h
index 43a967729..46f6f3932 100644
--- a/src/muz/rel/dl_sparse_table.h
+++ b/src/muz/rel/dl_sparse_table.h
@@ -72,7 +72,7 @@ namespace datalog {
         ~sparse_table_plugin() override;
 
         bool can_handle_signature(const table_signature & s) override
-        { return s.size()>0; }
+        { return !s.empty(); }
 
         table_base * mk_empty(const table_signature & s) override;
         sparse_table * mk_clone(const sparse_table & t);
diff --git a/src/muz/spacer/spacer_context.cpp b/src/muz/spacer/spacer_context.cpp
index bad25ef71..76e7e24c6 100644
--- a/src/muz/spacer/spacer_context.cpp
+++ b/src/muz/spacer/spacer_context.cpp
@@ -3058,7 +3058,7 @@ expr_ref context::get_ground_sat_answer() const {
                 ground_fact_conjs.push_back(m.mk_eq(sig_arg, sig_val));
                 ground_arg_vals.push_back(sig_val);
             }
-            if (ground_fact_conjs.size () > 0) {
+            if (!ground_fact_conjs.empty()) {
                 expr_ref ground_fact(m);
                 ground_fact = mk_and(ground_fact_conjs);
                 m_pm.formula_o2n(ground_fact, ground_fact, i);
diff --git a/src/muz/spacer/spacer_iuc_solver.cpp b/src/muz/spacer/spacer_iuc_solver.cpp
index 27b8ee357..32f33f773 100644
--- a/src/muz/spacer/spacer_iuc_solver.cpp
+++ b/src/muz/spacer/spacer_iuc_solver.cpp
@@ -72,7 +72,7 @@ app* iuc_solver::mk_proxy (expr *v)
         if (is_uninterp_const(e)) { return to_app(v); }
     }
 
-    def_manager &def = m_defs.size () > 0 ? m_defs.back () : m_base_defs;
+    def_manager &def = !m_defs.empty() ? m_defs.back () : m_base_defs;
     return def.mk_proxy (v);
 }
 
diff --git a/src/muz/transforms/dl_mk_array_instantiation.cpp b/src/muz/transforms/dl_mk_array_instantiation.cpp
index 626109528..a94383453 100644
--- a/src/muz/transforms/dl_mk_array_instantiation.cpp
+++ b/src/muz/transforms/dl_mk_array_instantiation.cpp
@@ -253,7 +253,7 @@ namespace datalog {
         all_selects.push_back(rewrite_select(array, select_ops[i]));
       }
     }
-    if(all_selects.size()==0)
+    if(all_selects.empty())
     {
       expr_ref_vector dummy_args(m);
       dummy_args.push_back(array);
diff --git a/src/opt/opt_context.cpp b/src/opt/opt_context.cpp
index a6f3d8152..d418bd437 100644
--- a/src/opt/opt_context.cpp
+++ b/src/opt/opt_context.cpp
@@ -481,7 +481,7 @@ namespace opt {
                 ++j;
             }
         }
-        if (r == l_true && m_box_models.size() > 0) {
+        if (r == l_true && !m_box_models.empty()) {
             m_model = m_box_models[0];
         }
         return r;
diff --git a/src/qe/nlarith_util.cpp b/src/qe/nlarith_util.cpp
index 12977b449..c2d95a1ee 100644
--- a/src/qe/nlarith_util.cpp
+++ b/src/qe/nlarith_util.cpp
@@ -684,7 +684,7 @@ namespace nlarith {
 
         void get_coefficients(poly const& p, app*& a, app*& b, app*& c) {
             a = b = c = z();
-            if (p.size() > 0) c = p[0];
+            if (!p.empty()) c = p[0];
             if (p.size() > 1) b = p[1];
             if (p.size() > 2) a = p[2];
             SASSERT(p.size() <= 3);
@@ -1359,7 +1359,7 @@ namespace nlarith {
         void quot_rem(poly const& u, poly const& v, poly& q, poly& r, app_ref& lc, unsigned& power) {
             lc = v.empty()?num(0):v[v.size()-1];
             power = 0;
-            if (u.size() < v.size() || v.size() == 0) {
+            if (u.size() < v.size() || v.empty()) {
                 q.reset();
                 r.reset();
                 r.append(u);
diff --git a/src/qe/qe_arith.cpp b/src/qe/qe_arith.cpp
index cd81167e3..a0aea08da 100644
--- a/src/qe/qe_arith.cpp
+++ b/src/qe/qe_arith.cpp
@@ -387,7 +387,7 @@ namespace qe {
             for (row const& r : rows) {
                 expr_ref_vector ts(m);
                 expr_ref t(m), s(m), val(m);
-                if (r.m_vars.size() == 0) {
+                if (r.m_vars.empty()) {
                     continue;
                 }
                 if (r.m_vars.size() == 1 && r.m_vars[0].m_coeff.is_neg() && r.m_type != opt::t_mod) {
diff --git a/src/smt/proto_model/array_factory.cpp b/src/smt/proto_model/array_factory.cpp
index dc3e0f89c..141021006 100644
--- a/src/smt/proto_model/array_factory.cpp
+++ b/src/smt/proto_model/array_factory.cpp
@@ -104,7 +104,7 @@ bool array_factory::mk_two_diff_values_for(sort * s) {
 
 bool array_factory::get_some_values(sort * s, expr_ref & v1, expr_ref & v2) {
     value_set * set = nullptr;
-    if (!m_sort2value_set.find(s, set) || set->size() == 0) {
+    if (!m_sort2value_set.find(s, set) || set->empty()) {
         if (!mk_two_diff_values_for(s))
             return false;
     }
diff --git a/src/smt/smt_case_split_queue.cpp b/src/smt/smt_case_split_queue.cpp
index 5c51b906f..6290ed14d 100644
--- a/src/smt/smt_case_split_queue.cpp
+++ b/src/smt/smt_case_split_queue.cpp
@@ -281,7 +281,7 @@ namespace smt {
             }
         }
         if (order == 1) {
-            if (undef_children.size() == 0) {
+            if (undef_children.empty()) {
                 // a bug?
             } else if (undef_children.size() == 1) {
                 undef_child = undef_children[0];
diff --git a/src/smt/theory_arith_aux.h b/src/smt/theory_arith_aux.h
index f70e50ece..ae0286c59 100644
--- a/src/smt/theory_arith_aux.h
+++ b/src/smt/theory_arith_aux.h
@@ -548,7 +548,7 @@ namespace smt {
             if (!it->is_dead()) {
                 row const & r = m_rows[it->m_row_id];
                 theory_var s  = r.get_base_var();
-                if (is_quasi_base(s) && m_var_occs[s].size() == 0)
+                if (is_quasi_base(s) && m_var_occs[s].empty())
                     continue;
                 if (is_int(v)) {
                     numeral const & c = r[it->m_row_idx].m_coeff;
@@ -574,7 +574,7 @@ namespace smt {
         TRACE("move_unconstrained_to_base", tout << "before...\n"; display(tout););
         int num = get_num_vars();
         for (theory_var v = 0; v < num; v++) {
-            if (m_var_occs[v].size() == 0 && is_free(v)) {
+            if (m_var_occs[v].empty() && is_free(v)) {
                 switch (get_var_kind(v)) {
                 case QUASI_BASE:
                     break;
diff --git a/src/smt/theory_array_full.cpp b/src/smt/theory_array_full.cpp
index 4e1de7b90..3e474df81 100644
--- a/src/smt/theory_array_full.cpp
+++ b/src/smt/theory_array_full.cpp
@@ -141,7 +141,7 @@ namespace smt {
     }
 
     void theory_array_full::set_prop_upward(theory_var v, var_data* d) {
-        if (m_params.m_array_always_prop_upward || d->m_stores.size() >= 1) {
+        if (m_params.m_array_always_prop_upward || !d->m_stores.empty()) {
             theory_array::set_prop_upward(v, d);
         }
         else {
diff --git a/src/smt/theory_recfun.h b/src/smt/theory_recfun.h
index 46392c6d2..95b20eb4b 100644
--- a/src/smt/theory_recfun.h
+++ b/src/smt/theory_recfun.h
@@ -125,7 +125,7 @@ namespace smt {
         
         literal mk_eq_lit(expr* l, expr* r);
         bool is_standard_order(recfun::vars const& vars) const { 
-            return vars.size() == 0 || vars[vars.size()-1]->get_idx() == 0; 
+            return vars.empty() || vars[vars.size()-1]->get_idx() == 0;
         }
     protected:
         void push_case_expand(case_expansion* e) { m_q_case_expand.push_back(e); }
diff --git a/src/smt/theory_seq.cpp b/src/smt/theory_seq.cpp
index 5a85628e8..947eb44ad 100644
--- a/src/smt/theory_seq.cpp
+++ b/src/smt/theory_seq.cpp
@@ -3570,18 +3570,18 @@ void theory_seq::apply_sort_cnstr(enode* n, sort* s) {
 }
 
 void theory_seq::display(std::ostream & out) const {
-    if (m_eqs.size() == 0 &&
-        m_nqs.size() == 0 &&
+    if (m_eqs.empty() &&
+        m_nqs.empty() &&
         m_rep.empty() &&
         m_exclude.empty()) {
         return;
     }
     out << "Theory seq\n";
-    if (m_eqs.size() > 0) {
+    if (!m_eqs.empty()) {
         out << "Equations:\n";
         display_equations(out);
     }
-    if (m_nqs.size() > 0) {
+    if (!m_nqs.empty()) {
         display_disequations(out);
     }
     if (!m_re2aut.empty()) {
@@ -3655,7 +3655,7 @@ std::ostream& theory_seq::display_disequation(std::ostream& out, ne const& e) co
     for (literal lit : e.lits()) {
         out << lit << " ";
     }
-    if (e.lits().size() > 0) {
+    if (!e.lits().empty()) {
         out << "\n";
     }
     for (unsigned j = 0; j < e.ls().size(); ++j) {
diff --git a/src/smt/theory_str.cpp b/src/smt/theory_str.cpp
index f0e11c248..3ee780366 100644
--- a/src/smt/theory_str.cpp
+++ b/src/smt/theory_str.cpp
@@ -2501,7 +2501,7 @@ namespace smt {
             }
         }
 
-        if (resolvedMap.size() == 0) {
+        if (resolvedMap.empty()) {
             // no simplification possible
             return node;
         } else {
@@ -5452,7 +5452,7 @@ namespace smt {
                             }
 
                             if (implyR) {
-                                if (litems1.size() == 0) {
+                                if (litems1.empty()) {
                                     assert_axiom(implyR);
                                 } else {
                                     assert_implication(mk_and(litems1), implyR);
@@ -7020,7 +7020,7 @@ namespace smt {
     bool theory_str::refine_automaton_lower_bound(eautomaton * aut, rational current_lower_bound, rational & refined_lower_bound) {
         ENSURE(aut != nullptr);
 
-        if (aut->final_states().size() < 1) {
+        if (aut->final_states().empty()) {
             // no solutions at all
             refined_lower_bound = rational::minus_one();
             return false;
@@ -8168,13 +8168,13 @@ namespace smt {
 
         // step 2: Concat == Constant
 
-        if (eqc_const_lhs.size() != 0) {
+        if (!eqc_const_lhs.empty()) {
             expr * conStr = *(eqc_const_lhs.begin());
             std::set<expr*>::iterator itor2 = eqc_concat_rhs.begin();
             for (; itor2 != eqc_concat_rhs.end(); itor2++) {
                 solve_concat_eq_str(*itor2, conStr);
             }
-        } else if (eqc_const_rhs.size() != 0) {
+        } else if (!eqc_const_rhs.empty()) {
             expr* conStr = *(eqc_const_rhs.begin());
             std::set<expr*>::iterator itor1 = eqc_concat_lhs.begin();
             for (; itor1 != eqc_concat_lhs.end(); itor1++) {
@@ -8250,7 +8250,7 @@ namespace smt {
         ast_manager & m = get_manager();
 
         int hasCommon = 0;
-        if (eqc_concat_lhs.size() != 0 && eqc_concat_rhs.size() != 0) {
+        if (!eqc_concat_lhs.empty() && !eqc_concat_rhs.empty()) {
             std::set<expr*>::iterator itor1 = eqc_concat_lhs.begin();
             std::set<expr*>::iterator itor2 = eqc_concat_rhs.begin();
             for (; itor1 != eqc_concat_lhs.end(); itor1++) {
@@ -8570,13 +8570,13 @@ namespace smt {
         obj_map<expr, std::stack<T_cut *> >::iterator varItor = cut_var_map.begin();
         while (varItor != cut_var_map.end()) {
             std::stack<T_cut*> & val = cut_var_map[varItor->m_key];
-            while ((val.size() > 0) && (val.top()->level != 0) && (val.top()->level >= sLevel)) {
+            while ((!val.empty()) && (val.top()->level != 0) && (val.top()->level >= sLevel)) {
                 // TRACE("str", tout << "remove cut info for " << mk_pp(e, get_manager()) << std::endl; print_cut_var(e, tout););
                 // T_cut * aCut = val.top();
                 val.pop();
                 // dealloc(aCut);
             }
-            if (val.size() == 0) {
+            if (val.empty()) {
                 cutvarmap_removes.insert(varItor->m_key);
             }
             varItor++;
@@ -9402,7 +9402,7 @@ namespace smt {
             }
         }
 
-        if (depMap.size() == 0) {
+        if (depMap.empty()) {
             std::map<expr*, int>::iterator itor = strVarMap.begin();
             for (; itor != strVarMap.end(); itor++) {
                 expr * var = get_alias_index_ast(aliasIndexMap, itor->first);
@@ -10801,7 +10801,7 @@ namespace smt {
             expr * var = fvIt2->first;
             tmpSet.clear();
             get_eqc_allUnroll(var, constValue, tmpSet);
-            if (tmpSet.size() > 0) {
+            if (!tmpSet.empty()) {
                 fv_unrolls_map[var] = tmpSet;
             }
         }
@@ -10935,7 +10935,7 @@ namespace smt {
             expr * var = fvIt1->first;
             fSimpUnroll.clear();
             get_eqc_simpleUnroll(var, constValue, fSimpUnroll);
-            if (fSimpUnroll.size() == 0) {
+            if (fSimpUnroll.empty()) {
                 gen_assign_unroll_reg(fv_unrolls_map[var]);
             } else {
                 expr * toAssert = gen_assign_unroll_Str2Reg(var, fSimpUnroll);
@@ -11548,7 +11548,7 @@ namespace smt {
             unroll_tries_map[var][unrolls].erase(e);
         }
 
-        if (unroll_tries_map[var][unrolls].size() == 0) {
+        if (unroll_tries_map[var][unrolls].empty()) {
             unroll_tries_map[var][unrolls].push_back(mk_unroll_test_var());
         }
 
diff --git a/src/smt/theory_utvpi_def.h b/src/smt/theory_utvpi_def.h
index b051c504a..fba549412 100644
--- a/src/smt/theory_utvpi_def.h
+++ b/src/smt/theory_utvpi_def.h
@@ -618,7 +618,7 @@ namespace smt {
         
         th_var v1 = null_theory_var, v2 = null_theory_var;
         bool   pos1 = true, pos2 = true;
-        if (terms.size() >= 1) {
+        if (!terms.empty()) {
             v1 = terms[0].first;
             pos1 = terms[0].second.is_one();
             SASSERT(v1 != null_theory_var);
diff --git a/src/solver/tactic2solver.cpp b/src/solver/tactic2solver.cpp
index 3a905bafd..492ddd443 100644
--- a/src/solver/tactic2solver.cpp
+++ b/src/solver/tactic2solver.cpp
@@ -170,7 +170,7 @@ lbool tactic2solver::check_sat_core(unsigned num_assumptions, expr * const * ass
             break;
         default: 
             m_result->set_status(l_undef);
-            if (reason_unknown != "")
+            if (!reason_unknown.empty())
                 m_result->m_unknown = reason_unknown;
             if (num_assumptions == 0 && m_scopes.empty()) {
                 m_assertions.reset();
diff --git a/src/tactic/bv/bv_bound_chk_tactic.cpp b/src/tactic/bv/bv_bound_chk_tactic.cpp
index 75b772720..cf35afef4 100644
--- a/src/tactic/bv/bv_bound_chk_tactic.cpp
+++ b/src/tactic/bv/bv_bound_chk_tactic.cpp
@@ -74,7 +74,7 @@ struct bv_bound_chk_rewriter_cfg : public default_rewriter_cfg {
         bv_bounds bvb(m());
         const br_status rv = bvb.rewrite(m_bv_ineq_consistency_test_max, f, num, args, result);
         if (rv != BR_FAILED && (m_m.is_false(result) || m_m.is_true(result))) m_stats.m_unsats++;
-        else if (rv != BR_FAILED && bvb.singletons().size()) m_stats.m_singletons++;
+        else if (rv != BR_FAILED && !bvb.singletons().empty()) m_stats.m_singletons++;
         else if (rv != BR_FAILED && is_app(result) && to_app(result)->get_num_args() < num) m_stats.m_reduces++;
         return rv;
     }
diff --git a/src/tactic/sls/sls_engine.cpp b/src/tactic/sls/sls_engine.cpp
index 1285e46cf..2aeb355ed 100644
--- a/src/tactic/sls/sls_engine.cpp
+++ b/src/tactic/sls/sls_engine.cpp
@@ -440,7 +440,7 @@ lbool sls_engine::search() {
 
         // get candidate variables
         ptr_vector<func_decl> & to_evaluate = m_tracker.get_unsat_constants(m_assertions);
-        if (!to_evaluate.size())
+        if (to_evaluate.empty())
         {
             res = l_true;
             goto bailout;
diff --git a/src/tactic/sls/sls_tracker.h b/src/tactic/sls/sls_tracker.h
index b730e78da..e10c91729 100644
--- a/src/tactic/sls/sls_tracker.h
+++ b/src/tactic/sls/sls_tracker.h
@@ -1003,7 +1003,7 @@ public:
     }
 
     ptr_vector<func_decl> & get_unsat_constants_walksat(expr * e) {
-            if (!e || m_temp_constants.size())
+            if (!e || !m_temp_constants.empty())
                 return m_temp_constants;
             ptr_vector<func_decl> const & this_decls = m_constants_occ.find(e);
             unsigned sz = this_decls.size();
diff --git a/src/tactic/tactic.cpp b/src/tactic/tactic.cpp
index 3b3c2444f..4a51c701a 100644
--- a/src/tactic/tactic.cpp
+++ b/src/tactic/tactic.cpp
@@ -191,7 +191,7 @@ lbool check_sat(tactic & t, goal_ref & g, model_ref & md, labels_vec & labels, p
         return l_false;
     }
     else {
-        if (models_enabled && r.size() >= 1) {
+        if (models_enabled && !r.empty()) {
         model_converter_ref mc = r[0]->mc();            
             model_converter2model(m, mc.get(), md);
             if (mc)
diff --git a/src/test/bit_vector.cpp b/src/test/bit_vector.cpp
index 487f6cdd0..db6270b35 100644
--- a/src/test/bit_vector.cpp
+++ b/src/test/bit_vector.cpp
@@ -35,7 +35,7 @@ static void tst1() {
     }
     else if (op <= 3) {
         ENSURE(v1.size() == v2.size());
-        if (v1.size() > 0) {
+        if (!v1.empty()) {
         bool val = (rand()%2) != 0;
         unsigned idx = rand()%v1.size();
         ENSURE(v1.get(idx) == v2[idx]);
@@ -46,7 +46,7 @@ static void tst1() {
     }
     else if (op <= 4) {
         ENSURE(v1.size() == v2.size());
-        if (v1.size() > 0) {
+        if (!v1.empty()) {
         unsigned idx = rand()%v1.size();
         VERIFY(v1.get(idx) == v2[idx]);
         }
diff --git a/src/test/chashtable.cpp b/src/test/chashtable.cpp
index 0ccf2c177..8e4dadf99 100644
--- a/src/test/chashtable.cpp
+++ b/src/test/chashtable.cpp
@@ -102,7 +102,7 @@ static void tst3() {
     ENSURE(t.contains(12));
     t.erase(12);
     t.erase(10);
-    ENSURE(t.size() == 0);
+    ENSURE(t.empty());
     ENSURE(t.empty());
     ENSURE(t.used_slots() == 0);
     t.insert(10);
diff --git a/src/test/lp/argument_parser.h b/src/test/lp/argument_parser.h
index ce59632d2..f2a74f122 100644
--- a/src/test/lp/argument_parser.h
+++ b/src/test/lp/argument_parser.h
@@ -117,7 +117,7 @@ public:
                 unknown_options.push_back(t);
             }
         }
-        if (unknown_options.size()) {
+        if (!unknown_options.empty()) {
             ret = "Unknown options:";
         }
         for (const auto & unknownOption : unknown_options) {
@@ -127,15 +127,15 @@ public:
         ret += "\n";
         ret += "Usage:\n";
         for (auto allowed_option : m_options)
-            ret += allowed_option.first + " " + (allowed_option.second.size() == 0 ? std::string("") : std::string("/") + allowed_option.second) + std::string("\n");
+            ret += allowed_option.first + " " + (allowed_option.second.empty() ? std::string("") : std::string("/") + allowed_option.second) + std::string("\n");
         for (auto s : m_options_with_after_string) {
-            ret += s.first + " " + (s.second.size() == 0? " \"option value\"":("\""+ s.second+"\"")) + "\n";
+            ret += s.first + " " + (s.second.empty()? " \"option value\"":("\""+ s.second+"\"")) + "\n";
         }
         return ret;
     }
 
     void print() {
-        if (m_used_options.size() == 0 && m_used_options_with_after_string.size() == 0 && m_free_args.size() == 0) {
+        if (m_used_options.empty() && m_used_options_with_after_string.empty() && m_free_args.empty()) {
             std::cout << "no options are given" << std::endl;
             return;
         }
@@ -146,7 +146,7 @@ public:
         for (auto & t : m_used_options_with_after_string) {
             std::cout << t.first << " " << t.second << std::endl;
         }
-        if (m_free_args.size() > 0) {
+        if (!m_free_args.empty()) {
             std::cout << "free arguments are: "  << std::endl;
             for (auto & t : m_free_args) {
                 std::cout << t << " " <<  std::endl;
diff --git a/src/test/lp/lp.cpp b/src/test/lp/lp.cpp
index 192bd46b0..f43aff668 100644
--- a/src/test/lp/lp.cpp
+++ b/src/test/lp/lp.cpp
@@ -1091,7 +1091,7 @@ void lp_solver_test() {
 
 bool get_int_from_args_parser(const char * option, argument_parser & args_parser, unsigned & n) {
     std::string s = args_parser.get_option_value(option);
-    if (s.size() > 0) {
+    if (!s.empty()) {
         n = atoi(s.c_str());
         return true;
     }
@@ -1100,7 +1100,7 @@ bool get_int_from_args_parser(const char * option, argument_parser & args_parser
 
 bool get_double_from_args_parser(const char * option, argument_parser & args_parser, double & n) {
     std::string s = args_parser.get_option_value(option);
-    if (s.size() > 0) {
+    if (!s.empty()) {
         n = atof(s.c_str());
         return true;
     }
@@ -1830,7 +1830,7 @@ std::unordered_map<std::string, double> * get_solution_from_glpsol_output(std::s
             return nullptr;
         }
         auto split = string_split(s, " \t", false);
-        if (split.size() == 0) {
+        if (split.empty()) {
             return ret;
         }
 
@@ -2050,14 +2050,14 @@ void finalize(unsigned ret) {
 
 void get_time_limit_and_max_iters_from_parser(argument_parser & args_parser, unsigned & time_limit, unsigned & max_iters) {
     std::string s = args_parser.get_option_value("--max_iters");
-    if (s.size() > 0) {
+    if (!s.empty()) {
         max_iters = atoi(s.c_str());
     } else {
         max_iters = 0;
     }
 
     std::string time_limit_string = args_parser.get_option_value("--time_limit");
-    if (time_limit_string.size() > 0) {
+    if (!time_limit_string.empty()) {
         time_limit = atoi(time_limit_string.c_str());
     } else {
         time_limit = 0;
@@ -2156,7 +2156,7 @@ double get_lp_tst_cost(std::string file_name) {
             cost_string = str;
         }
     }
-    if (cost_string.size() == 0) {
+    if (cost_string.empty()) {
         std::cout << "cannot find the cost line in " << file_name << std::endl;
         throw 0;
     }
@@ -2377,7 +2377,7 @@ std::unordered_map<std::string, lp::mpq> get_solution_map(lp_solver<lp::mpq, lp:
 
 void run_lar_solver(argument_parser & args_parser, lar_solver * solver, mps_reader<lp::mpq, lp::mpq> * reader) {
     std::string maxng = args_parser.get_option_value("--maxng");
-    if (maxng.size() > 0) {
+    if (!maxng.empty()) {
         solver->settings().max_number_of_iterations_with_no_improvements = atoi(maxng.c_str());
     }
     if (args_parser.option_is_used("-pd")){
@@ -2385,7 +2385,7 @@ void run_lar_solver(argument_parser & args_parser, lar_solver * solver, mps_read
     }
     
     std::string iter = args_parser.get_option_value("--max_iters");
-    if (iter.size() > 0) {
+    if (!iter.empty()) {
         solver->settings().max_total_number_of_iterations = atoi(iter.c_str());
     }
     if (args_parser.option_is_used("--compare_with_primal")){
@@ -2470,7 +2470,7 @@ vector<std::string> get_file_names_from_file_list(std::string filelist) {
         std::string s = read_line(end, file);
         if (end)
             break;
-        if (s.size() == 0)
+        if (s.empty())
             break;
         ret.push_back(s);
     } while (true);
@@ -2480,13 +2480,13 @@ vector<std::string> get_file_names_from_file_list(std::string filelist) {
 void test_lar_solver(argument_parser & args_parser) {
 
     std::string file_name = args_parser.get_option_value("--file");
-    if (file_name.size() > 0) {
+    if (!file_name.empty()) {
         test_lar_on_file(file_name, args_parser);
         return;
     }
 
     std::string file_list = args_parser.get_option_value("--filelist");
-    if (file_list.size() > 0) {
+    if (!file_list.empty()) {
         for (const std::string & fn : get_file_names_from_file_list(file_list))
             test_lar_on_file(fn, args_parser);
         return;
@@ -3600,7 +3600,7 @@ void test_lp_local(int argn, char**argv) {
         
     
     std::string lufile = args_parser.get_option_value("--checklu");
-    if (lufile.size()) {
+    if (!lufile.empty()) {
         check_lu_from_file(lufile);
         return finalize(0);
     }
@@ -3623,7 +3623,7 @@ void test_lp_local(int argn, char**argv) {
         return finalize(0);
     }
     std::string file_list = args_parser.get_option_value("--filelist");
-    if (file_list.size() > 0) {
+    if (!file_list.empty()) {
         for (const std::string & fn : get_file_names_from_file_list(file_list))
             solve_mps(fn, args_parser);
         return finalize(0);
@@ -3704,7 +3704,7 @@ void test_lp_local(int argn, char**argv) {
     bool dual = args_parser.option_is_used("--dual");
     bool solve_for_rational = args_parser.option_is_used("--mpq");
     std::string file_name = args_parser.get_option_value("--file");
-    if (file_name.size() > 0) {
+    if (!file_name.empty()) {
         solve_mps(file_name, args_parser.option_is_used("--min"), max_iters, time_limit, solve_for_rational, dual, args_parser.option_is_used("--compare_with_primal"), args_parser);
         ret = 0;
         return finalize(ret);
diff --git a/src/test/lp/smt_reader.h b/src/test/lp/smt_reader.h
index 16f44e3b3..5d386862c 100644
--- a/src/test/lp/smt_reader.h
+++ b/src/test/lp/smt_reader.h
@@ -52,7 +52,7 @@ namespace lp {
             std::string m_head;
             std::vector<lisp_elem> m_elems;
             void print() {
-                if (m_elems.size()) {
+                if (!m_elems.empty()) {
                     std::cout << '(';
                     std::cout << m_head << ' ';
                     for (auto & el : m_elems)
@@ -133,7 +133,7 @@ namespace lp {
             lm.m_head = m_line.substr(0, separator);
             m_line = m_line.substr(lm.m_head.size());
             eat_blanks();
-            while (m_line.size()) {
+            while (!m_line.empty()) {
                 if (m_line[0] == '(') {
                     lisp_elem el;
                     fill_nested_elem(el);
@@ -152,7 +152,7 @@ namespace lp {
         }
 
         void eat_blanks() {
-            while (m_line.size()) {
+            while (!m_line.empty()) {
                 if (m_line[0] == ' ')
                     m_line = m_line.substr(1);
                 else
@@ -205,7 +205,7 @@ namespace lp {
 
 
         bool is_integer(std::string & s) {
-            if (s.size() == 0) return false;
+            if (s.empty()) return false;
             return atoi(s.c_str()) != 0 || isdigit(s.c_str()[0]);
         }
 
diff --git a/src/test/vector.cpp b/src/test/vector.cpp
index 4632a9c29..c9a93dee4 100644
--- a/src/test/vector.cpp
+++ b/src/test/vector.cpp
@@ -41,7 +41,7 @@ static void tst1() {
         v1.pop_back();
     }
     ENSURE(v1.empty());
-    ENSURE(v1.size() == 0);
+    ENSURE(v1.empty());
     unsigned i = 1000000000;
     while (true) {
         std::cout << "resize " << i << "\n";
diff --git a/src/util/lp/core_solver_pretty_printer_def.h b/src/util/lp/core_solver_pretty_printer_def.h
index dcf3e0a11..5453c6085 100644
--- a/src/util/lp/core_solver_pretty_printer_def.h
+++ b/src/util/lp/core_solver_pretty_printer_def.h
@@ -183,7 +183,7 @@ template <typename T, typename X> unsigned core_solver_pretty_printer<T, X>:: ge
     }
     if (!m_core_solver.use_tableau()) {
         w = std::max(w, (unsigned)T_to_string(m_exact_column_norms[column]).size());
-        if (m_core_solver.m_column_norms.size() > 0)
+        if (!m_core_solver.m_column_norms.empty())
             w = std::max(w, (unsigned)T_to_string(m_core_solver.m_column_norms[column]).size());
     }
     return w;
@@ -339,7 +339,7 @@ template <typename T, typename X> void core_solver_pretty_printer<T, X>::print()
     print_lows();
     print_upps();
     print_exact_norms();
-    if (m_core_solver.m_column_norms.size() > 0)
+    if (!m_core_solver.m_column_norms.empty())
         print_approx_norms();
     m_out << std::endl;
 }
diff --git a/src/util/lp/eta_matrix_def.h b/src/util/lp/eta_matrix_def.h
index 5c7661e24..774cc89dc 100644
--- a/src/util/lp/eta_matrix_def.h
+++ b/src/util/lp/eta_matrix_def.h
@@ -81,7 +81,7 @@ void eta_matrix<T, X>::apply_from_right(vector<T> & w) {
 }
 template <typename T, typename X>
 void eta_matrix<T, X>::apply_from_right(indexed_vector<T> & w) {
-    if (w.m_index.size() == 0)
+    if (w.m_index.empty())
         return;
 #ifdef Z3DEBUG
     // vector<T> wcopy(w.m_data);
diff --git a/src/util/lp/general_matrix.h b/src/util/lp/general_matrix.h
index 1c643161a..f6f93c705 100644
--- a/src/util/lp/general_matrix.h
+++ b/src/util/lp/general_matrix.h
@@ -51,7 +51,7 @@ public:
 
     
     unsigned row_count() const { return m_data.size(); }
-    unsigned column_count() const { return m_data.size() > 0? m_data[0].size() : 0; }
+    unsigned column_count() const { return !m_data.empty()? m_data[0].size() : 0; }
 
     class ref_row {
         general_matrix& m_matrix;
diff --git a/src/util/lp/lar_term.h b/src/util/lp/lar_term.h
index e9259b8c0..64243f4e2 100644
--- a/src/util/lp/lar_term.h
+++ b/src/util/lp/lar_term.h
@@ -37,7 +37,7 @@ struct lar_term {
     }
 
     bool is_empty() const {
-        return m_coeffs.size() == 0; // && is_zero(m_v);
+        return m_coeffs.empty(); // && is_zero(m_v);
     }
     
     unsigned size() const { return static_cast<unsigned>(m_coeffs.size()); }
diff --git a/src/util/lp/lp_dual_core_solver_def.h b/src/util/lp/lp_dual_core_solver_def.h
index e7ab73928..984f2e560 100644
--- a/src/util/lp/lp_dual_core_solver_def.h
+++ b/src/util/lp/lp_dual_core_solver_def.h
@@ -665,7 +665,7 @@ template <typename T, typename X> bool lp_dual_core_solver<T, X>::ratio_test() {
     m_flipped_boxed.clear();
     int initial_delta_sign = m_delta >= numeric_traits<T>::zero()? 1: -1;
     do {
-        if (m_breakpoint_set.size() == 0) {
+        if (m_breakpoint_set.empty()) {
             set_status_to_tentative_dual_unbounded_or_dual_unbounded();
             return false;
         }
@@ -697,7 +697,7 @@ template <typename T, typename X> void lp_dual_core_solver<T, X>::update_d_and_x
         this->m_d[j] -= m_theta_D * this->m_pivot_row[j];
     }
     this->m_d[m_p] = - m_theta_D;
-    if (m_flipped_boxed.size() > 0) {
+    if (!m_flipped_boxed.empty()) {
         process_flipped();
         update_xb_after_bound_flips();
     }
diff --git a/src/util/lp/lp_primal_core_solver_def.h b/src/util/lp/lp_primal_core_solver_def.h
index d86ebf548..a43764172 100644
--- a/src/util/lp/lp_primal_core_solver_def.h
+++ b/src/util/lp/lp_primal_core_solver_def.h
@@ -504,7 +504,7 @@ lp_primal_core_solver<T, X>::get_bound_on_variable_and_update_leaving_precisely(
         X tt = - (this->m_lower_bounds[j] - this->m_x[j]) / m;
         if (numeric_traits<X>::is_neg(tt))
             tt = zero_of_type<X>();
-        if (leavings.size() == 0 || tt < t || (tt == t && m > abs_of_d_of_leaving)) {
+        if (leavings.empty() || tt < t || (tt == t && m > abs_of_d_of_leaving)) {
             t = tt;
             abs_of_d_of_leaving = m;
             leavings.clear();
@@ -524,7 +524,7 @@ lp_primal_core_solver<T, X>::get_bound_on_variable_and_update_leaving_precisely(
         X tt = (this->m_upper_bounds[j] - this->m_x[j]) / m;
         if (numeric_traits<X>::is_neg(tt))
             tt = zero_of_type<X>();
-        if (leavings.size() == 0 || tt < t || (tt == t && - m > abs_of_d_of_leaving)) {
+        if (leavings.empty() || tt < t || (tt == t && - m > abs_of_d_of_leaving)) {
             t = tt;
             abs_of_d_of_leaving = - m;
             leavings.clear();
diff --git a/src/util/lp/lp_solver_def.h b/src/util/lp/lp_solver_def.h
index 9b385dee6..21a86efba 100644
--- a/src/util/lp/lp_solver_def.h
+++ b/src/util/lp/lp_solver_def.h
@@ -103,7 +103,7 @@ template <typename T, typename X> void lp_solver<T, X>::flip_costs() {
 
 template <typename T, typename X>    bool lp_solver<T, X>::problem_is_empty() {
     for (auto & c : m_A_values)
-        if (c.second.size())
+        if (!c.second.empty())
             return false;
     return true;
 }
@@ -387,7 +387,7 @@ template <typename T, typename X> unsigned lp_solver<T, X>::try_to_remove_some_r
             return 0;
         }
     }
-    if (rows_to_delete.size() > 0) {
+    if (!rows_to_delete.empty()) {
         for (unsigned k : rows_to_delete) {
             m_A_values.erase(k);
         }
diff --git a/src/util/lp/matrix_def.h b/src/util/lp/matrix_def.h
index 361540cae..b74e59443 100644
--- a/src/util/lp/matrix_def.h
+++ b/src/util/lp/matrix_def.h
@@ -97,7 +97,7 @@ void print_matrix_with_widths(vector<vector<std::string>> & A, vector<unsigned>
 void print_string_matrix(vector<vector<std::string>> & A, std::ostream & out, unsigned blanks_in_front) {
     vector<unsigned> widths;
 
-    if (A.size() > 0)
+    if (!A.empty())
         for (unsigned j = 0; j < A[0].size(); j++) {
             widths.push_back(get_width_of_column(j, A));
         }
diff --git a/src/util/lp/mps_reader.h b/src/util/lp/mps_reader.h
index 09762cd5e..2ef07af6e 100644
--- a/src/util/lp/mps_reader.h
+++ b/src/util/lp/mps_reader.h
@@ -220,7 +220,7 @@ class mps_reader {
                 *m_message_stream << "cannot read from file" << std::endl;
             }
             m_line_number++;
-            if (m_line.size() != 0 && m_line[0] != '*' && !all_white_space())
+            if (!m_line.empty() && m_line[0] != '*' && !all_white_space())
                 break;
         }
     }
@@ -514,7 +514,7 @@ class mps_reader {
         lp_assert(m_line.size() >= 14);
         vector<std::string> bound_string = split_and_trim(m_line.substr(name_offset, m_line.size()));
 
-        if (bound_string.size() == 0) {
+        if (bound_string.empty()) {
             set_m_ok_to_false();
             (*m_message_stream) << "error at line " << m_line_number << std::endl;
             throw m_line;
diff --git a/src/util/lp/square_sparse_matrix_def.h b/src/util/lp/square_sparse_matrix_def.h
index cc6625453..2fc101666 100644
--- a/src/util/lp/square_sparse_matrix_def.h
+++ b/src/util/lp/square_sparse_matrix_def.h
@@ -248,7 +248,7 @@ void square_sparse_matrix<T, X>::put_max_index_to_0(vector<indexed_value<T>> & r
 
 template <typename T, typename X>
 void square_sparse_matrix<T, X>::set_max_in_row(vector<indexed_value<T>> & row_vals) {
-    if (row_vals.size() == 0)
+    if (row_vals.empty())
         return;
     T max_val = abs(row_vals[0].m_value);
     unsigned max_index = 0;
@@ -386,7 +386,7 @@ bool square_sparse_matrix<T, X>::set_row_from_work_vector_and_clean_work_vector_
     }
     work_vec.m_index.clear();
     auto & row_vals = m_rows[i0];
-    if (row_vals.size() == 0) {
+    if (row_vals.empty()) {
         return false;
     }
     set_max_in_row(row_vals);  // it helps to find larger pivots
diff --git a/src/util/mpn.cpp b/src/util/mpn.cpp
index b8cab4a9f..25445bc89 100644
--- a/src/util/mpn.cpp
+++ b/src/util/mpn.cpp
@@ -381,7 +381,7 @@ char * mpn_manager::to_string(mpn_digit const * a, size_t const lng, char * buf,
             div_1(t_numer, t_denom[0], &temp[0]);
             div_unnormalize(t_numer, t_denom, d, &rem);
             buf[j++] = '0' + rem;
-            while (temp.size() > 0 && temp.back() == 0) 
+            while (!temp.empty() && temp.back() == 0)
                 temp.pop_back();
         }
         buf[j] = 0;