由于数据的长度和平台相关，所以基于 64 位系统比较。
| 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 比较同步。另外 ssize_t 和 size_t 的关系就像 int 和 unsigned int 的关系。（参考1，参考2）
| 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 |
（参考）
#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;
}Windows
Linux
无符号整型unsigned int、unsigned long、usigned long long、size_t比较和格式控制
原文：https://www.cnblogs.com/hereis00/p/9994312.html