posted Dec 1, 2014, 2:44 AM by Javad Taghia
std::size_t is the unsigned integer type of the result of the sizeof operator as well as the sizeof... operator and the alignof operator (since C++11).
std::size_t can store the maximum size of a theoretically possible object of any type (including array). On many platforms (an exception are systems with segmented addressing) std::size_t can safely store the value of any non-member pointer, in which case it is synonymous with std::uintptr_t.
std::size_t is commonly used for array indexing and loop counting. Programs that use other types, such as unsigned int, for array indexing may fail on, e.g. 64-bit systems when the index exceeds UINT_MAX or if it relies on 32-bit modular arithmetic.
When indexing C++ containers, such as std::string, std::vector, etc, the appropriate type is the member typedef size_type provided by such containers. It is usually defined as a synonym for std::size_t.
const std::size_t N = 100;
int* a = new int[N];
for (std::size_t n = 0; n < N; ++n)
a[n] = n;
|signed integer type returned when subtracting two pointers |
|byte offset from the beginning of a standard-layout type to specified member |