c - printf ("%.d", 0) 和 printf ("%.1d", 0) 有什么区别？

Question

我正在重新编码 printf我现在被精确标记阻止了一会儿。所以我读到类型转换说明符时的默认精度是 d是 1:



所以我认为 %.d 之间没有区别和 %.1d ，但是当我测试时:

printf(".d =%.d, .1d= %.1d", 0, 0);

我确实找到了一个:

.d =, .1d= 0

Answer 1

如果您使用 .之后 %没有指定精度，它被设置为零。

From the printf page on cppreference.com :

. followed by integer number or *, or neither that specifies precision of the conversion. In the case when * is used, the precision is specified by an additional argument of type int. If the value of this argument is negative, it is ignored. If neither a number nor * is used, the precision is taken as zero.

默认为 1如果您使用 %d (没有 . ):

printf("d = %d, 1d= %1d", 0, 0);
# Output:   d = 0, 1d= 0