無符號整型 unsigned int、unsigned long、usigned long long、size_t 比較和格式控制

位數比較

由於數據的長度和平台相關，所以基於 64 位系統比較。

	Windows	Linux
unsigned int	32 bits/4294967295	32 bits
unsigned long	32 bits	64 bits/18446744073709551615
unsigned long long	64 bits	64 bits
size_t	32 bits	64 bits

可以看到，size_t 和 unsigned long 比較同步。另外 ssize_t 和 size_t 的關系就像 int 和 unsigned int 的關系。（參考1，參考2）

格式控制（printf）

length	d i	u o x X	f F e E g G a A	c	s	p	n
(none)	int	unsigned int	double	int	char*	void*	int*
hh	signed char	unsigned char					signed char*
h	short int	unsigned short int					short int*
l	long int	unsigned long int		wint_t	wchar_t*		long int*
ll	long long int	unsigned long long int					long long int*
j	intmax_t	uintmax_t					intmax_t*
z	size_t	size_t					size_t*
t	ptrdiff_t	ptrdiff_t					ptrdiff_t*
L			long double

（參考）

測試代碼

#include <cstdio>
int main()
{
    unsigned int ui = -1;
    unsigned long ul = -1;
    unsigned long long ull = -1;
    size_t st = -1;
    printf("ui=%u,ul=%lu,ull=%llu,st=%zu\n", ui, ul, ull, st);
    return 0;
}

測試結果

• Windows
  

• Linux