Question

I’m reviewing another developer’s code, which contains the following:

std::string name;
...
std::string::size_type colon = name.find(":");

I’m arguing that using size_t would be easier to understand and just as safe, since the STL standard states that std::string is std::basic_string<char, std::allocator>, and std::allocator::size_type is size_t.

He wants assurance that that the STL standard couldn’t possibly ever change to make this assumption invalid; if the standard could change, then size_type would be safer than size_t.

Could that happen? Is there any other reason to use size_type rather than size_t?

Answer 1

size_type should be used in code templated on the container type. When the code you have always operates on std::string, you can just use size_t.