std::vector<Foo>::size_type与std::size_t相同并不是不必要.即使对于C ++ 11也是如此.

It is not necessarily true that std::vector<Foo>::size_type is the same as std::size_t. This is true even for C++11.

但就我个人而言，无论类型如何，我都将std::size_t用于std::vector索引.

But personally I use std::size_t for a std::vector index irrespective of the type.

如果您特别勤奋，则可以始终使用静态断言.显然，static_assert是C ++ 98以后的新增内容，但是按照该标准，您可以使用类似

You could always use a static assertion if you're feeling particularly diligent. Obviously static_assert is a later addition beyond what's in C++98, but in that standard you could use something like

static char wrong_size_1[1 + sizeof(std::size_t) - sizeof(std::vector<Foo>::size_type)];

static char wrong_size_2[1 - sizeof(std::size_t) + sizeof(std::vector<Foo>::size_type)];

如果类型类型的大小不同，则会导致编译时失败.

which would induce compile time failures if type types are not the same size.