size_t vs int in C++ and/or C

Question

Why is it that in C++ containers, it returns a size_type rather than an int? If we\'re creating our own structures, should we also be encouraged to

Answer 1

All containers in the stl have various typedefs. For example, value_type is the element type, and size_type is the number stored type. In this way the containers are completely generic based on platform and implementation.

If you are creating your own containers, you should use size_type too. Typically this is done

typedef std::size_t size_type;

If you want a container's size, you should write

typedef vector ints;
ints v;
v.push_back(4);
ints::size_type s = v.size();

What's nice is that if later you want to use a list, just change the typedef to

typedef list ints;

And it will still work!