diff --git a/src/ansi-c/c_typecheck_expr.cpp b/src/ansi-c/c_typecheck_expr.cpp
index 185c576e401..4b84899fc1a 100644
--- a/src/ansi-c/c_typecheck_expr.cpp
+++ b/src/ansi-c/c_typecheck_expr.cpp
@@ -2566,7 +2566,7 @@ exprt c_typecheck_baset::do_special_functions(
     // http://gcc.gnu.org/onlinedocs/gcc-4.1.1/gcc/Atomic-Builtins.html
 
     // adjust return type of function to match pointer subtype
-    if(expr.arguments().size()<1)
+    if(expr.arguments().empty())
     {
       err_location(f_op);
       error() << "__sync_* primitives take as least one argument" << eom;
diff --git a/src/ansi-c/expr2c.cpp b/src/ansi-c/expr2c.cpp
index c50d075abaa..dc0c469b64c 100644
--- a/src/ansi-c/expr2c.cpp
+++ b/src/ansi-c/expr2c.cpp
@@ -2588,7 +2588,7 @@ std::string expr2ct::convert_code_switch(
   const codet &src,
   unsigned indent)
 {
-  if(src.operands().size()<1)
+  if(src.operands().empty())
   {
     unsigned precedence;
     return convert_norep(src, precedence);
diff --git a/src/clobber/clobber_parse_options.cpp b/src/clobber/clobber_parse_options.cpp
index 42aadee4326..3026dc3e6aa 100644
--- a/src/clobber/clobber_parse_options.cpp
+++ b/src/clobber/clobber_parse_options.cpp
@@ -192,7 +192,7 @@ bool clobber_parse_optionst::get_goto_program(
   const optionst &options,
   goto_functionst &goto_functions)
 {
-  if(cmdline.args.size()==0)
+  if(cmdline.args.empty())
   {
     error() << "Please provide a program to verify" << eom;
     return true;
diff --git a/src/cpp/cpp_typecheck_compound_type.cpp b/src/cpp/cpp_typecheck_compound_type.cpp
index 6e2cce31d74..bb0b207e699 100644
--- a/src/cpp/cpp_typecheck_compound_type.cpp
+++ b/src/cpp/cpp_typecheck_compound_type.cpp
@@ -466,7 +466,7 @@ void cpp_typecheckt::typecheck_compound_declarator(
         {
           is_virtual=true;
           const code_typet &code_type=to_code_type(comp.type());
-          assert(code_type.parameters().size()>0);
+          assert(!code_type.parameters().empty());
           const typet &pointer_type=code_type.parameters()[0].type();
           assert(pointer_type.id()==ID_pointer);
           virtual_bases.insert(pointer_type.subtype().get(ID_identifier));
diff --git a/src/cpp/cpp_typecheck_conversions.cpp b/src/cpp/cpp_typecheck_conversions.cpp
index 1e33634ebef..cc357d1fb21 100644
--- a/src/cpp/cpp_typecheck_conversions.cpp
+++ b/src/cpp/cpp_typecheck_conversions.cpp
@@ -574,13 +574,13 @@ bool cpp_typecheckt::standard_conversion_pointer_to_member(
        expr.type().subtype().id()==ID_code)
     {
       code_typet code1=to_code_type(expr.type().subtype());
-      assert(code1.parameters().size()>0);
+      assert(!code1.parameters().empty());
       code_typet::parametert this1=code1.parameters()[0];
       assert(this1.get(ID_C_base_name)==ID_this);
       code1.parameters().erase(code1.parameters().begin());
 
       code_typet code2=to_code_type(type.subtype());
-      assert(code2.parameters().size()>0);
+      assert(!code2.parameters().empty());
       code_typet::parametert this2=code2.parameters()[0];
       assert(this2.get(ID_C_base_name)==ID_this);
       code2.parameters().erase(code2.parameters().begin());
diff --git a/src/cpp/cpp_typecheck_expr.cpp b/src/cpp/cpp_typecheck_expr.cpp
index 979572c717e..e2926f09607 100644
--- a/src/cpp/cpp_typecheck_expr.cpp
+++ b/src/cpp/cpp_typecheck_expr.cpp
@@ -1431,7 +1431,7 @@ void cpp_typecheckt::typecheck_expr_cpp_name(
       // http://gcc.gnu.org/onlinedocs/gcc-4.1.1/gcc/Atomic-Builtins.html
 
       // adjust return type of function to match pointer subtype
-      if(fargs.operands.size()<1)
+      if(fargs.operands.empty())
       {
         error().source_location=source_location;
         error() << "__sync_* primitives take as least one argument"
diff --git a/src/goto-cc/compile.cpp b/src/goto-cc/compile.cpp
index aa3256da590..f9184b86598 100644
--- a/src/goto-cc/compile.cpp
+++ b/src/goto-cc/compile.cpp
@@ -102,13 +102,13 @@ bool compilet::doit()
     return true;
   }
 
-  if(mode==LINK_LIBRARY && source_files.size()>0)
+  if(mode==LINK_LIBRARY && !source_files.empty())
   {
     error() << "cannot link source files" << eom;
     return true;
   }
 
-  if(mode==PREPROCESS_ONLY && object_files.size()>0)
+  if(mode==PREPROCESS_ONLY && !object_files.empty())
   {
     error() << "cannot preprocess object files" << eom;
     return true;
@@ -117,7 +117,7 @@ bool compilet::doit()
   const unsigned warnings_before=
     get_message_handler().get_message_count(messaget::M_WARNING);
 
-  if(source_files.size()>0)
+  if(!source_files.empty())
     if(compile())
       return true;
 
@@ -346,7 +346,7 @@ bool compilet::link()
   convert_symbols(compiled_functions);
 
   // parse object files
-  while(object_files.size()>0)
+  while(!object_files.empty())
   {
     std::string file_name=object_files.front();
     object_files.pop_front();
diff --git a/src/goto-cc/xml_binaries/xml_goto_function.cpp b/src/goto-cc/xml_binaries/xml_goto_function.cpp
index ff35c86e253..589838154fe 100644
--- a/src/goto-cc/xml_binaries/xml_goto_function.cpp
+++ b/src/goto-cc/xml_binaries/xml_goto_function.cpp
@@ -33,6 +33,5 @@ void convert(const xmlt &xml, goto_functionst::goto_functiont &function)
 {
   function.body.clear();
   convert(xml, function.body);
-  function.body_available = function.body.instructions.size()>0;
   // don't forget to fix the functions type via the symbol table!
 }
diff --git a/src/goto-cc/xml_binaries/xml_goto_function_hashing.cpp b/src/goto-cc/xml_binaries/xml_goto_function_hashing.cpp
index 8d578451fac..23769f5b441 100644
--- a/src/goto-cc/xml_binaries/xml_goto_function_hashing.cpp
+++ b/src/goto-cc/xml_binaries/xml_goto_function_hashing.cpp
@@ -38,6 +38,5 @@ void xml_goto_function_convertt::convert(
   xml_goto_program_convertt gpconverter(ireps_container);
   function.body.clear();
   gpconverter.convert(xml, function.body);
-  function.body_available = function.body.instructions.size()>0;
   // don't forget to fix the functions type via the symbol table!
 }
diff --git a/src/goto-cc/xml_binaries/xml_symbol.cpp b/src/goto-cc/xml_binaries/xml_symbol.cpp
index e62ebe7f657..a323d4ef2ab 100644
--- a/src/goto-cc/xml_binaries/xml_symbol.cpp
+++ b/src/goto-cc/xml_binaries/xml_symbol.cpp
@@ -54,7 +54,7 @@ void convert(const symbolt &sym, xmlt &root)
   flags.new_element("base_name").data=id2string(sym.base_name);
   flags.new_element("module").data=id2string(sym.module);
 
-  if(sym.pretty_name.size()>0)
+  if(!sym.pretty_name.empty())
     flags.new_element("pretty_name").data=id2string(sym.pretty_name);
 
   xmlt &xmlloc = xmlsym.new_element("location");
diff --git a/src/goto-instrument/accelerate/acceleration_utils.cpp b/src/goto-instrument/accelerate/acceleration_utils.cpp
index 0bd48d492b3..7da7a6dce8d 100644
--- a/src/goto-instrument/accelerate/acceleration_utils.cpp
+++ b/src/goto-instrument/accelerate/acceleration_utils.cpp
@@ -573,7 +573,7 @@ bool acceleration_utilst::do_arrays(
             << " array assignments\n";
 #endif
 
-  if(array_assignments.size()==0)
+  if(array_assignments.empty())
   {
     // The loop doesn't write to any arrays.  We're done!
     return true;
diff --git a/src/goto-instrument/accelerate/trace_automaton.cpp b/src/goto-instrument/accelerate/trace_automaton.cpp
index 705225cfba9..ac885fcf0f4 100644
--- a/src/goto-instrument/accelerate/trace_automaton.cpp
+++ b/src/goto-instrument/accelerate/trace_automaton.cpp
@@ -366,7 +366,7 @@ void automatont::reverse(goto_programt::targett epsilon)
     transitions.push_back(transitionst());
   }
 
-  if(accept_states.size()==0)
+  if(accept_states.empty())
   {
     num_states=0;
     return;
diff --git a/src/goto-instrument/rw_set.h b/src/goto-instrument/rw_set.h
index eba731d705c..15c3766f23c 100644
--- a/src/goto-instrument/rw_set.h
+++ b/src/goto-instrument/rw_set.h
@@ -266,13 +266,13 @@ class rw_set_with_trackt:public _rw_set_loct
 
   void track_deref(const entryt &entry, bool read)
   {
-    if(dereferencing && dereferenced.size()==0)
+    if(dereferencing && dereferenced.empty())
     {
       dereferenced.insert(dereferenced.begin(), entry);
       if(read)
         set_reads.insert(entry.object);
     }
-    else if(dereferencing && dereferenced.size()>0)
+    else if(dereferencing && !dereferenced.empty())
       dereferenced_from.insert(
         std::make_pair(entry.object, dereferenced.front().object));
   }
diff --git a/src/goto-instrument/wmm/cycle_collection.cpp b/src/goto-instrument/wmm/cycle_collection.cpp
index 1012ae40cdc..465b013aa6f 100644
--- a/src/goto-instrument/wmm/cycle_collection.cpp
+++ b/src/goto-instrument/wmm/cycle_collection.cpp
@@ -521,21 +521,21 @@ bool event_grapht::graph_explorert::backtrack(
 
       std::stack<event_idt> tmp;
 
-      while(marked_stack.size()>0 && marked_stack.top()!=vertex)
+      while(!marked_stack.empty() && marked_stack.top()!=vertex)
       {
         tmp.push(marked_stack.top());
         mark[marked_stack.top()]=false;
         marked_stack.pop();
       }
 
-      if(marked_stack.size()>0)
+      if(!marked_stack.empty())
       {
         assert(marked_stack.top()==vertex);
         mark[vertex]=true;
       }
       else
       {
-        while(tmp.size()>0)
+        while(!tmp.empty())
         {
           marked_stack.push(tmp.top());
           mark[tmp.top()]=true;
diff --git a/src/goto-instrument/wmm/event_graph.cpp b/src/goto-instrument/wmm/event_graph.cpp
index 9342a9268f8..d5d9df2aff4 100644
--- a/src/goto-instrument/wmm/event_graph.cpp
+++ b/src/goto-instrument/wmm/event_graph.cpp
@@ -55,7 +55,7 @@ void event_grapht::print_rec_graph(std::ofstream &file, event_idt node_id,
 
 void event_grapht::print_graph()
 {
-  assert(po_order.size()>0);
+  assert(!po_order.empty());
   std::set<event_idt> visited;
   event_idt root=po_order.front();
   std::ofstream file;
@@ -113,7 +113,7 @@ event_idt event_grapht::copy_segment(event_idt begin, event_idt end)
   /* collects the nodes of the subgraph */
   explore_copy_segment(covered, begin, end);
 
-  if(covered.size()==0)
+  if(covered.empty())
     return end;
 
 //  for(std::set<event_idt>::const_iterator it=covered.begin();
diff --git a/src/goto-instrument/wmm/event_graph.h b/src/goto-instrument/wmm/event_graph.h
index 7670059ed43..61428a934a0 100644
--- a/src/goto-instrument/wmm/event_graph.h
+++ b/src/goto-instrument/wmm/event_graph.h
@@ -178,7 +178,7 @@ class event_grapht
       {
         critical_cyclet reduced(egraph, id);
         this->hide_internals(reduced);
-        assert(reduced.size()>0);
+        assert(!reduced.empty());
         return print_name(reduced, model);
       }
       else
diff --git a/src/goto-instrument/wmm/weak_memory.cpp b/src/goto-instrument/wmm/weak_memory.cpp
index 0e9f0e8904c..5b0c4163f83 100644
--- a/src/goto-instrument/wmm/weak_memory.cpp
+++ b/src/goto-instrument/wmm/weak_memory.cpp
@@ -189,7 +189,7 @@ void weak_memory(
       <<" cycles found"<<messaget::eom;
 
     /* if no cycle, no need to instrument */
-    if(instrumenter.set_of_cycles.size() == 0)
+    if(instrumenter.set_of_cycles.empty())
     {
       message.status()<<"program safe -- no need to instrument"<<messaget::eom;
       return;
diff --git a/src/goto-programs/builtin_functions.cpp b/src/goto-programs/builtin_functions.cpp
index 3de38da7b8e..1dbc622b780 100644
--- a/src/goto-programs/builtin_functions.cpp
+++ b/src/goto-programs/builtin_functions.cpp
@@ -233,7 +233,7 @@ void goto_convertt::do_scanf(
 
   if(f_id==CPROVER_PREFIX "scanf")
   {
-    if(arguments.size()<1)
+    if(arguments.empty())
     {
       error().source_location=function.find_source_location();
       error() << "scanf takes at least one argument" << eom;
@@ -1328,7 +1328,7 @@ void goto_convertt::do_function_call_symbol(
   }
   else if(identifier==CPROVER_PREFIX "fence")
   {
-    if(arguments.size()<1)
+    if(arguments.empty())
     {
       error().source_location=function.find_source_location();
       error() << "`" << identifier
diff --git a/src/goto-programs/interpreter_evaluate.cpp b/src/goto-programs/interpreter_evaluate.cpp
index b3cc2523e5b..43a072cfaf4 100644
--- a/src/goto-programs/interpreter_evaluate.cpp
+++ b/src/goto-programs/interpreter_evaluate.cpp
@@ -144,7 +144,7 @@ void interpretert::evaluate(
   }
   else if(expr.id()==ID_or)
   {
-    if(expr.operands().size()<1)
+    if(expr.operands().empty())
       throw id2string(expr.id())+" expects at least one operand";
 
     bool result=false;
@@ -188,7 +188,7 @@ void interpretert::evaluate(
   }
   else if(expr.id()==ID_and)
   {
-    if(expr.operands().size()<1)
+    if(expr.operands().empty())
       throw id2string(expr.id())+" expects at least one operand";
 
     bool result=true;
diff --git a/src/goto-programs/remove_unused_functions.cpp b/src/goto-programs/remove_unused_functions.cpp
index 986f615ba6b..5f41e1d6084 100644
--- a/src/goto-programs/remove_unused_functions.cpp
+++ b/src/goto-programs/remove_unused_functions.cpp
@@ -33,7 +33,7 @@ void remove_unused_functions(
 
   messaget message(message_handler);
 
-  if(unused_functions.size()>0)
+  if(!unused_functions.empty())
   {
     message.statistics()
       << "Dropping " << unused_functions.size() << " of " <<
diff --git a/src/goto-programs/show_goto_functions_json.cpp b/src/goto-programs/show_goto_functions_json.cpp
index da9c2424322..ea25d5c0f7f 100644
--- a/src/goto-programs/show_goto_functions_json.cpp
+++ b/src/goto-programs/show_goto_functions_json.cpp
@@ -76,7 +76,7 @@ json_objectt show_goto_functions_jsont::convert(
         instruction_entry["instruction"]=
           json_stringt(instruction_builder.str());
 
-        if(instruction.code.operands().size()>0)
+        if(!instruction.code.operands().empty())
         {
           json_arrayt operand_array;
           for(const exprt &operand : instruction.code.operands())
diff --git a/src/java_bytecode/java_bytecode_convert_method.cpp b/src/java_bytecode/java_bytecode_convert_method.cpp
index dd3cb32ce26..871f82b6c11 100644
--- a/src/java_bytecode/java_bytecode_convert_method.cpp
+++ b/src/java_bytecode/java_bytecode_convert_method.cpp
@@ -1772,7 +1772,7 @@ codet java_bytecode_convert_methodt::convert_instructions(
     }
     else if(statement=="putfield")
     {
-      assert(op.size()==2 && results.size()==0);
+      assert(op.size()==2 && results.empty());
       code_blockt block;
       save_stack_entries(
         "stack_field",
@@ -1948,7 +1948,7 @@ codet java_bytecode_convert_methodt::convert_instructions(
     else if(statement=="tableswitch" ||
             statement=="lookupswitch")
     {
-      assert(op.size()==1 && results.size()==0);
+      assert(op.size()==1 && results.empty());
 
       // we turn into switch-case
       code_switcht code_switch;
@@ -2298,7 +2298,7 @@ codet java_bytecode_convert_methodt::convert_instructions(
       code_labelt newlabel(label(std::to_string(address)), code_blockt());
       root_block.move_to_operands(newlabel);
       root.branch.push_back(block_tree_nodet::get_leaf());
-      assert((root.branch_addresses.size()==0 ||
+      assert((root.branch_addresses.empty() ||
               root.branch_addresses.back()<address) &&
              "Block addresses should be unique and increasing");
       root.branch_addresses.push_back(address);
diff --git a/src/java_bytecode/java_bytecode_language.cpp b/src/java_bytecode/java_bytecode_language.cpp
index 7ba75b1d8f4..85205c7525d 100644
--- a/src/java_bytecode/java_bytecode_language.cpp
+++ b/src/java_bytecode/java_bytecode_language.cpp
@@ -507,7 +507,7 @@ bool java_bytecode_languaget::do_ci_lazy_method_conversion(
   do
   {
     any_new_methods=false;
-    while(method_worklist2.size()!=0)
+    while(!method_worklist2.empty())
     {
       std::swap(method_worklist1, method_worklist2);
       for(const auto &mname : method_worklist1)
diff --git a/src/memory-models/mmcc_parse_options.cpp b/src/memory-models/mmcc_parse_options.cpp
index 586aea20ec3..5a458332016 100644
--- a/src/memory-models/mmcc_parse_options.cpp
+++ b/src/memory-models/mmcc_parse_options.cpp
@@ -48,7 +48,7 @@ int mmcc_parse_optionst::doit()
 
       return convert(in, cmdline.args[0]);
     }
-    else if(cmdline.args.size()==0)
+    else if(cmdline.args.empty())
     {
       return convert(std::cin, "stdin");
     }
diff --git a/src/musketeer/cycles_visitor.cpp b/src/musketeer/cycles_visitor.cpp
index 89d68e13ad5..6e220cae17e 100644
--- a/src/musketeer/cycles_visitor.cpp
+++ b/src/musketeer/cycles_visitor.cpp
@@ -347,7 +347,7 @@ void cycles_visitort::com_constraint(
 
   std::list<event_idt>::const_iterator e_it=C_j.begin();
   std::list<event_idt>::const_iterator next_it=e_it;
-  assert(C_j.size()>0);
+  assert(!C_j.empty());
   ++next_it;
   for(;  next_it!=C_j.end() && e_it!=C_j.end(); ++e_it, ++next_it)
   {
diff --git a/src/musketeer/fencer.cpp b/src/musketeer/fencer.cpp
index 1f612d35e3b..86de5d8fc8b 100644
--- a/src/musketeer/fencer.cpp
+++ b/src/musketeer/fencer.cpp
@@ -111,7 +111,7 @@ void fence_weak_memory(
       << " cycles found" << messaget::eom;
 
     /* if no cycle, no need to instrument */
-    if(instrumenter.set_of_cycles.size() == 0)
+    if(instrumenter.set_of_cycles.empty())
     {
       message.result()
         << "program safe -- no need to place additional fences"
diff --git a/src/musketeer/graph_visitor.cpp b/src/musketeer/graph_visitor.cpp
index 2ecca9e8651..5c46243958d 100644
--- a/src/musketeer/graph_visitor.cpp
+++ b/src/musketeer/graph_visitor.cpp
@@ -35,7 +35,7 @@ void const_graph_visitort::graph_explore(
       edges.insert(fence_inserter.add_edge(edget(*it, *next_it)));
     }
   }
-  else if(egraph.po_out(next).size()==0)
+  else if(egraph.po_out(next).empty())
   {
     /* this path is not connecting a to b => return */
   }
@@ -76,7 +76,7 @@ void const_graph_visitort::const_graph_explore(
       fence_inserter.add_edge(edget(*it, *next_it));
     }
   }
-  else if(egraph.po_out(next).size()==0)
+  else if(egraph.po_out(next).empty())
   {
     /* this path is not connecting a to b => return */
   }
@@ -106,7 +106,7 @@ void const_graph_visitort::graph_explore_BC(
   bool porw)
 {
   /* TODO: restricts to C_1 U ... U C_n for perf improvement */
-  assert(old_path.size()>0);
+  assert(!old_path.empty());
 
   fence_inserter.instrumenter.message.debug() << "(BC) explore "
                                               << old_path.front()
@@ -129,7 +129,7 @@ void const_graph_visitort::graph_explore_BC(
       break;
     }
 
-  if(egraph.po_out(next).size()==0 || no_other_pos)
+  if(egraph.po_out(next).empty() || no_other_pos)
   {
     /* inserts all the pos collected from old_path in edges */
     std::list<event_idt>::const_iterator it=old_path.begin();
@@ -184,7 +184,7 @@ void const_graph_visitort::const_graph_explore_BC(
       break;
     }
 
-  if(egraph.po_out(next).size()==0 || no_other_pos)
+  if(egraph.po_out(next).empty() || no_other_pos)
   {
     /* inserts all the pos collected from old_path in edges */
     std::list<event_idt>::const_iterator it=old_path.begin();
@@ -244,7 +244,7 @@ void const_graph_visitort::graph_explore_AC(
       break;
     }
 
-  if(egraph.po_in(next).size()==0 || no_other_pos)
+  if(egraph.po_in(next).empty() || no_other_pos)
   {
     /* inserts all the pos collected from old_path in edges */
     std::list<event_idt>::const_iterator it=old_path.begin();
@@ -300,7 +300,7 @@ void const_graph_visitort::const_graph_explore_AC(
     }
 
   /* if beginning of the thread */
-  if(egraph.po_in(next).size()==0 || no_other_pos)
+  if(egraph.po_in(next).empty() || no_other_pos)
   {
     /* inserts all the pos collected from old_path in edges */
     std::list<event_idt>::const_iterator it=old_path.begin();
diff --git a/src/musketeer/propagate_const_function_pointers.cpp b/src/musketeer/propagate_const_function_pointers.cpp
index 07838ce8d35..fa96cb63a75 100644
--- a/src/musketeer/propagate_const_function_pointers.cpp
+++ b/src/musketeer/propagate_const_function_pointers.cpp
@@ -151,7 +151,7 @@ void const_function_pointer_propagationt::dup_caller_and_inline_callee(
   const symbol_exprt &const_function,
   unsigned stack_scope)
 {
-  assert(callsite_stack.size()>0);
+  assert(!callsite_stack.empty());
 
   /* for the reconstruction of the {call,callsite}_stacks after the
      duplication */
@@ -209,8 +209,7 @@ void const_function_pointer_propagationt::dup_caller_and_inline_callee(
         it!=function_dup.body.instructions.end(); ++it)
         it->function=function_new_id;
 
-      assert(goto_functions.function_map[function_new_id].
-             body.instructions.size()>0);
+      assert(goto_functions.function_map[function_new_id].body.empty());
 
       /* removes in definition the argument leading to the const_function */
       code_typet::parameterst &args=function_dup.type.parameters();
diff --git a/src/pointer-analysis/value_set.cpp b/src/pointer-analysis/value_set.cpp
index 9c30fbe3ca7..f6a9f128c5c 100644
--- a/src/pointer-analysis/value_set.cpp
+++ b/src/pointer-analysis/value_set.cpp
@@ -536,7 +536,7 @@ void value_sett::get_value_set_rec(
 
         get_value_set_rec(expr.op0(), tmp, suffix, original_type, ns);
 
-        if(tmp.read().size()==0)
+        if(tmp.read().empty())
         {
           // if not, throw in integer
           insert(dest, exprt(ID_integer_address, unsigned_char_type()));
diff --git a/src/pointer-analysis/value_set_fivr.cpp b/src/pointer-analysis/value_set_fivr.cpp
index 2acb06ad601..9c8edfeb769 100644
--- a/src/pointer-analysis/value_set_fivr.cpp
+++ b/src/pointer-analysis/value_set_fivr.cpp
@@ -104,7 +104,7 @@ void value_set_fivrt::output(
     }
 
     out << display_name << "={ ";
-    if(object_map.read().size()!=0)
+    if(!object_map.read().empty())
       out << "\n      ";
 
     std::size_t width=0;
diff --git a/src/pointer-analysis/value_set_fivrns.cpp b/src/pointer-analysis/value_set_fivrns.cpp
index 034b0839da0..63373e09226 100644
--- a/src/pointer-analysis/value_set_fivrns.cpp
+++ b/src/pointer-analysis/value_set_fivrns.cpp
@@ -95,7 +95,7 @@ void value_set_fivrnst::output_entry(
   const object_mapt &object_map=e.object_map;
 
   out << display_name << " = { ";
-  if(object_map.read().size()!=0)
+  if(!object_map.read().empty())
     out << "\n      ";
 
   std::size_t width=0;
diff --git a/src/solvers/flattening/boolbv.cpp b/src/solvers/flattening/boolbv.cpp
index 3c6de247d15..b3edb8e24cf 100644
--- a/src/solvers/flattening/boolbv.cpp
+++ b/src/solvers/flattening/boolbv.cpp
@@ -501,7 +501,7 @@ literalt boolbvt::convert_rest(const exprt &expr)
 
     const bvt &bv=convert_bv(operands[0]);
 
-    if(bv.size()<1)
+    if(bv.empty())
       throw "sign operator takes one non-empty operand";
 
     if(operands[0].type().id()==ID_signedbv)
diff --git a/src/solvers/flattening/boolbv_not.cpp b/src/solvers/flattening/boolbv_not.cpp
index b0f33f76b9c..e88955b10f6 100644
--- a/src/solvers/flattening/boolbv_not.cpp
+++ b/src/solvers/flattening/boolbv_not.cpp
@@ -13,7 +13,7 @@ bvt boolbvt::convert_not(const not_exprt &expr)
 {
   const bvt &op_bv=convert_bv(expr.op());
 
-  if(op_bv.size()<1)
+  if(op_bv.empty())
     throw "not operator takes one non-empty operand";
 
   const typet &op_type=expr.op().type();
diff --git a/src/solvers/flattening/boolbv_reduction.cpp b/src/solvers/flattening/boolbv_reduction.cpp
index 2e2850fd2c8..8472a16cc5c 100644
--- a/src/solvers/flattening/boolbv_reduction.cpp
+++ b/src/solvers/flattening/boolbv_reduction.cpp
@@ -13,7 +13,7 @@ literalt boolbvt::convert_reduction(const unary_exprt &expr)
 {
   const bvt &op_bv=convert_bv(expr.op());
 
-  if(op_bv.size()<1)
+  if(op_bv.empty())
     throw "reduction operators take one non-empty operand";
 
   enum { O_OR, O_AND, O_XOR } op;
@@ -53,7 +53,7 @@ bvt boolbvt::convert_bv_reduction(const unary_exprt &expr)
 {
   const bvt &op_bv=convert_bv(expr.op());
 
-  if(op_bv.size()<1)
+  if(op_bv.empty())
     throw "reduction operators take one non-empty operand";
 
   enum { O_OR, O_AND, O_XOR } op;
diff --git a/src/solvers/prop/prop_conv.cpp b/src/solvers/prop/prop_conv.cpp
index f7274994d16..72caa7ec6e2 100644
--- a/src/solvers/prop/prop_conv.cpp
+++ b/src/solvers/prop/prop_conv.cpp
@@ -415,7 +415,7 @@ void prop_conv_solvert::set_to(const exprt &expr, bool value)
           // Special case for a CNF-clause,
           // i.e., a constraint that's a disjunction.
 
-          if(expr.operands().size()>0)
+          if(!expr.operands().empty())
           {
             bvt bv;
             bv.reserve(expr.operands().size());
diff --git a/src/solvers/sat/satcheck_glucose.cpp b/src/solvers/sat/satcheck_glucose.cpp
index adcfbded617..cb511843956 100644
--- a/src/solvers/sat/satcheck_glucose.cpp
+++ b/src/solvers/sat/satcheck_glucose.cpp
@@ -154,7 +154,7 @@ propt::resultt satcheck_glucose_baset<T>::prop_solve()
       {
         messaget::status() <<
           "SAT checker: instance is SATISFIABLE" << eom;
-        assert(solver->model.size()!=0);
+        assert(!solver->model.empty());
         status=SAT;
         return P_SATISFIABLE;
       }
diff --git a/src/solvers/sat/satcheck_minisat2.cpp b/src/solvers/sat/satcheck_minisat2.cpp
index cab952930f6..1cd70665814 100644
--- a/src/solvers/sat/satcheck_minisat2.cpp
+++ b/src/solvers/sat/satcheck_minisat2.cpp
@@ -155,7 +155,7 @@ propt::resultt satcheck_minisat2_baset<T>::prop_solve()
         {
           messaget::status() <<
             "SAT checker: instance is SATISFIABLE" << eom;
-          assert(solver->model.size()!=0);
+          assert(!solver->model.empty());
           status=statust::SAT;
           return resultt::P_SATISFIABLE;
         }
diff --git a/src/solvers/smt2/smt2_conv.cpp b/src/solvers/smt2/smt2_conv.cpp
index 11f6b4c5dd1..a26dd2445c6 100644
--- a/src/solvers/smt2/smt2_conv.cpp
+++ b/src/solvers/smt2/smt2_conv.cpp
@@ -2833,7 +2833,7 @@ void smt2_convt::convert_relation(const exprt &expr)
 
 void smt2_convt::convert_plus(const plus_exprt &expr)
 {
-  if(expr.operands().size()==0)
+  if(expr.operands().empty())
   {
     INVALIDEXPR("No operands to plus");
   }
diff --git a/src/util/ieee_float.cpp b/src/util/ieee_float.cpp
index 448719b8465..5f8828ca76b 100644
--- a/src/util/ieee_float.cpp
+++ b/src/util/ieee_float.cpp
@@ -302,7 +302,7 @@ std::string ieee_floatt::to_string_scientific(std::size_t precision) const
     std::string exponent_str=
       integer2string(base10_digits(_fraction)+_exponent-1);
 
-    if(exponent_str.size()>0 && exponent_str[0]!='-')
+    if(!exponent_str.empty() && exponent_str[0]!='-')
       result+='+';
 
     result+=exponent_str;
diff --git a/src/util/json_irep.cpp b/src/util/json_irep.cpp
index 7f8c0b58b16..3cefcb9306c 100644
--- a/src/util/json_irep.cpp
+++ b/src/util/json_irep.cpp
@@ -52,7 +52,7 @@ void json_irept::convert_sub_tree(
   const irept::subt &sub_trees,
   json_objectt &parent) const
 {
-  if(sub_trees.size()>0)
+  if(!sub_trees.empty())
   {
     json_arrayt sub_objects;
     for(const irept &sub_tree : sub_trees)
@@ -77,7 +77,7 @@ void json_irept::convert_named_sub_tree(
   const irept::named_subt &sub_trees,
   json_objectt &parent) const
 {
-  if(sub_trees.size()>0)
+  if(!sub_trees.empty())
   {
     json_objectt sub_objects;
     for(const auto &sub_tree : sub_trees)
diff --git a/src/util/lispirep.cpp b/src/util/lispirep.cpp
index e31af4595cd..49fb6dc323b 100644
--- a/src/util/lispirep.cpp
+++ b/src/util/lispirep.cpp
@@ -15,7 +15,7 @@ void lisp2irep(const lispexprt &src, irept &dest)
 {
   dest.make_nil();
 
-  if(src.type!=lispexprt::List || src.size()<1)
+  if(src.type!=lispexprt::List || src.empty())
     return;
 
   dest.id(src[0].value);
diff --git a/src/xmllang/graphml.cpp b/src/xmllang/graphml.cpp
index 54d19654ec1..3a0591f8eca 100644
--- a/src/xmllang/graphml.cpp
+++ b/src/xmllang/graphml.cpp
@@ -152,7 +152,7 @@ static bool build_graph(
   graphmlt &dest,
   graphmlt::node_indext &entry)
 {
-  assert(dest.size()==0);
+  assert(dest.empty());
 
   name_mapt name_to_node;
   std::map<std::string, std::map<std::string, std::string> > defaults;