c - sprintf中的pcmC%iD%ip参数

Question

这行代码会做什么。

pcm->card->number，pcm->device都是int。

char str[16];

sprintf(str, "pcmC%iD%ip", pcm->card->number, pcm->device);

它取自 android/kernel/sound/core/pcm.c。

Answer 1

截至the description of sprintf()和 fprintf() , %i 是

The int argument is converted to a signed decimal in the style [-]dddd. The precision specifies the minimum number of digits to appear; if the value being converted can be represented in fewer digits, it will be expanded with leading zeros. The default precision is 1. The result of converting 0 with an explicit precision of 0 is no characters.

所以结果是例如pcmC12D23p 如果 pcm->card->number == 12 和 pcm->device == 23。