size_t. A basic unsigned integer C/C++ type. It is the type of the result returned by sizeof operator. The type's size is chosen so that it could store the maximum size of a theoretically possible array of any type. On a 32-bit system size_t will take 32 bits and on a 64-bit one - 64 bits. In other words, a pointer can be safely put inside size_t type (an exception is class-function-pointers but this is a special case). size_t type is usually used for loop, array indexing, size storage and address arithmetic. Although size_t can store a pointer, it is better to use another unsinged integer type uintptr_t for that purpose (its name reflects its capability). In some cases using size_t type is more effective and safe than using a more habitual for the programmer unsigned type.
size_t is a base unsigned integer memsize-type defined in the standard library of C/C++ languages. This type is described in the header file stddef.h for C and in the file cstddef for C++. Types defined by the header file stddef.h are located in the global namespace while cstddef places the size_t type in the namespace std. Since the standard header file stddef.h of the C language is included into C++ programs for the purpose of compatibility, in these programs you may address the type both in the global namespace (::size_t, size_t) and namespace std (std::size_t).
In the terms of static analyzer PVS-Studio, type size_t refers to memsize-types. The analyzer includes Viva64 system for detailed error detection in 64-bit programs and for code optimization. Many diagnostic messages shown by Viva64 analyzer relate to recommendations on using memsize-types. Using memsize-types (such as size_t, ptrdiff_t, INT_PTR) instead of 32-bit types in 64-bit programs allows you to:
To learn more about the errors you can avoid when using size_t type and also how this type allows improving and optimizing your 64-bit programs, see the articles given in the references.
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