Question

When I attempt this:

string msm_arg1;

…

if (msm_arg1 = "--console" )
run_console();

I get:

res/functions/ReadArgs.h|40|error: could not convert ‘msm_arg1.std::basic_string<_CharT, _Traits, _Alloc>::operator= [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>, std::basic_string<_CharT, _Traits, _Alloc> = std::basic_string<char>](((const char*)"-c"))’ from ‘std::basic_string<char>’ to ‘bool’|

What I’m seeing is that it is trying to compare a string (msm_arg1) to a bool, which “–console” clearly isn’t.

I can see one possible way around: creating a string to compare to, but with plently of possible CLI arguments, that could become messy.

I am using Code::Blocks on Ubuntu 11:10 with the default gcc.

Answer 1

= is the assignment operator.

At present, your code does this:

   if (msm_arg1 = "--console")
//     \____________________/
//       assign to msm_arg1;
//      evaluate to new value
// 
   if (msm_arg1)
//     \______/
//      convert string to bool
//       for `if` comparison
//
// ERROR: Can't do that!

The equivalence operator in C++ is ==:

if (msm_arg1 == "--console")

---

Also it’s worth being aware that this is a case-sensitive comparison, and that it won’t work properly at all if you stop using std::string and attempt to compare two literals.