c - 警告 : '0' flag ignored with precision and ‘%i’ gnu_printf format

Question

使用 gcc 4.4.1 在 Ubuntu Karmic 上编译一些旧版 C 代码时，我收到以下警告

警告是:

src/filename.c:385: warning: '0' flag ignored with precision and ‘%i’ gnu_printf format

导致发出警告的代码段是:

 char     buffer[256] ;
 long     fnum ;
 /* some initialization code here ... */
 sprintf(buffer, "F%03.3i.DTA", (int)fnum);  /* <- warning emitted here */

我想我理解这个警告，但我想在这里检查一下我是否正确，以及解决这个问题的(确定的)正确方法。

Answer 1

来自 printf(3)手册页:

   0      The value should be zero padded.  For d, i, o, u, x, X, a, A, e,
          E,  f, F, g, and G conversions, the converted value is padded on
          the left with zeros rather than blanks.  If the 0  and  -  flags
          both  appear,  the  0  flag is ignored.  If a precision is given
          with a numeric conversion (d, i, o, u, x, and X), the 0 flag  is
          ignored.  For other conversions, the behavior is undefined.

因此，您可以使用零填充或最小位数，但不能同时使用两者。