为什么“%.3i”打印前导零?

 1540-2837 (W) '0' flag is disregarded when combined with 
               precision and 'i' printf format.

下面的第一个printf模拟了程序中的结果。

#include <stdio.h>    
int main(void)
{
    int x = 3;

    printf("Format 0.3i <%0.3i>\n", x);  // prints 003, and AIX does a warning
    printf("Format  .3i <%.3i>\n", x);   // prints 003, with no warning
    printf("Format   3i <%3i>\n", x);    // prints   3, with no warning.

    return 0;
}