参考：
https://stackoverflow.com/questions/2524611/how-can-one-print-a-size-t-variable-portably-using-the-printf-family
size_t x = 111;
ssize_t y = -222;
printf("%zu\n", x); // prints as unsigned decimal
printf("%zx\n", x); // prints as hex
printf("%zd\n", y); // prints as signed decimal
标签：prints,decimal,printf,字符串,zu,size
From： https://www.cnblogs.com/tangjicheng/p/16857703.html