std::size_t
Defined in header
<cstddef>
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Defined in header
<cstdio>
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Defined in header
<cstring>
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Defined in header
<ctime>
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Defined in header
<cstdlib>
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(since C++11) |
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typedef /*implementation-defined*/ size_t;
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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).
[edit] Notes
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.
[edit] Example
#include <cstddef> int main() { const std::size_t N = 100; int* a = new int[N]; for (std::size_t n = 0; n < N; ++n) a[n] = n; delete[] a; }
[edit] See also
signed integer type returned when subtracting two pointers (typedef) |
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byte offset from the beginning of a standard-layout type to specified member (function macro) |
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C documentation for size_t
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