From Wikipedia The stdlib.h and stddef.h header files define a datatype called size_t1 which is used to represent the size of an object. Library functions that take sizes expect them to be of type size_t, and the sizeof operator evaluates to size_t. The actual type of size_t is platform-dependent; a common mistake is to assume … Read more
sizeof(), while looking like a function call, is actually an operator and part of the language core. No include needed. size_t is defined in various headers: stddef.h, string.h, stdlib.h, and stdio.h. Including any one of them is enough to use size_t in your code.
In the C++ standard, [support.types] (18.2) /6: “The type size_t is an implementation-defined unsigned integer type that is large enough to contain the size in bytes of any object.” This may or may not be the same as a “word size”, whatever that means.
The PRIuPTR macro (from <inttypes.h>) defines a decimal format for uintptr_t, which should always be large enough that you can cast a size_t to it without truncating, e.g. fprintf(stream, “Your size_t var has value %” PRIuPTR “.”, (uintptr_t) your_var);
You’ve encountered it in Microsoft’s C++ standard library, but it actually comes from C. C 11, to be precise, which means it’s not technically a part of C++. C 11 standard, Annex K introduced all the _s functions and the corresponding typedefs, including rsize_t. There is also a “maximum value” macro RSIZE_MAX which is large … Read more
As per C99, §7.17, size_t is not a builtin type but defined in <stddef.h>. Including the <stddef.h> header should fix your problem.
Yes, and this could be useful in some cases. Suppose you have a program that wishes to access more storage than will fit in virtual memory. By creating an allocator that references memory mapped storage and mapping it as required when indirecting pointer objects, you can access arbitrarily large amounts of memory. This remains conformant … Read more
ssize_t is used for functions whose return value could either be a valid size, or a negative value to indicate an error. It is guaranteed to be able to store values at least in the range [-1, SSIZE_MAX] (SSIZE_MAX is system-dependent). So you should use size_t whenever you mean to return a size in bytes, … Read more
It’s safe provided the int is zero or positive. If it’s negative, and size_t is of equal or higher rank than int, then the int will be converted to size_t and so its negative value will instead become a positive value. This new positive value is then compared to the size_t value, which may (in … Read more
The standard says that SIZE_MAX must be at least 65535. It specifies no upper bound, and gcc’s implementation is perfectly valid. Quoting the reference you cited (emphasis added): Its implementation-defined value shall be equal to or greater in magnitude (absolute value) than the corresponding value given below, with the same sign.