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
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
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
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
A cast, as Blaz Bratanic suggested: size_t data = 99999999; int convertdata = static_cast<int>(data); is likely to silence the warning (though in principle a compiler can warn about anything it likes, even if there’s a cast). But it doesn’t solve the problem that the warning was telling you about, namely that a conversion from size_t … Read more
A manifest constant (a macro) exists in C99 and it is called SIZE_MAX. There’s no such constant in C89/90 though. However, what you have in your original post is a perfectly portable method of finding the maximum value of size_t. It is guaranteed to work with any unsigned type.
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 printf format specifier %zu will work fine on C++ systems; there is no need to make it more complicated.
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
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