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
stddef.h is the C header. The name size_t is in global namespace in it. <cstddef>, on the other hand, is a C++ header which wraps the C names into std namespace, which is naturally the C++ approach, so if you include <cstddef> and the compiler is compliant you’ll have to use std::size_t . Clearly, in … Read more
C’s size_t and C++’s std::size_t are both same. In C, it’s defined in <stddef.h> and in C++, its defined in <cstddef> whose contents are the same as C header (see the quotation below). Its defined as unsigned integer type of the result of the sizeof operator. C Standard says in ยง17.7/2, size_t which is the … Read more
size_t is defined by the C standard to be the unsigned integer return type of the sizeof operator (C99 6.3.5.4.4), and the argument of malloc and friends (C99 7.20.3.3 etc). The actual range is set such that the maximum (SIZE_MAX) is at least 65535 (C99 7.18.3.2). However, this doesn’t let us determine sizeof(size_t). The implementation … Read more
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);
There seems to be confusion among the stackoverflow crowd concerning this ::size_t is defined in the backward compatibility header stddef.h . It’s been part of ANSI/ISO C and ISO C++ since their very beginning. Every C++ implementation has to ship with stddef.h (compatibility) and cstddef where only the latter defines std::size_t and not necessarily ::size_t. … Read more
The limit SIZE_MAX / 2 comes from the definitions of size_t and ptrdiff_t on your implementation, which choose that the types ptrdiff_t and size_t have the same width. C Standard mandates1 that type size_t is unsigned and type ptrdiff_t is signed. The result of difference between two pointers, will always2 have the type ptrdiff_t. This … Read more
Yes: use the z length modifier: size_t size = sizeof(char); printf(“the size is %zu\n”, size); // decimal size_t (“u” for unsigned) printf(“the size is %zx\n”, size); // hex size_t The other length modifiers that are available are hh (for char), h (for short), l (for long), ll (for long long), j (for intmax_t), t (for … Read more
The problem is not the compiler but the C library. MinGW uses Microsoft’s “Visual C Runtime” (msvcrt) which only conforms to c89 and it doesn’t support the z format specifier. Here’s what you can do to safely print a size_t when using MinGW: #include <inttypes.h> #include <stdio.h> #ifdef _WIN32 # ifdef _WIN64 # define PRI_SIZET … Read more
size_t is unsigned for historical reasons. On an architecture with 16 bit pointers, such as the “small” model DOS programming, it would be impractical to limit strings to 32 KB. For this reason, the C standard requires (via required ranges) ptrdiff_t, the signed counterpart to size_t and the result type of pointer difference, to be … Read more