c中的什么scanf函数返回？

Question

我知道签名是

int scanf(const char *format, ...)

这个int值与什么有关？

Answer 1

从man页面:

NAME
       scanf,  fscanf, sscanf, vscanf, vsscanf, vfscanf 

       ...

RETURN VALUE
       These functions return the number of input items  successfully  matched
       and assigned, which can be fewer than provided for, or even zero in the
       event of an early matching failure.

       The value EOF is returned if the end of input is reached before  either
       the  first  successful conversion or a matching failure occurs.  EOF is
       also returned if a read error occurs, in which case the error indicator
       for  the  stream  (see ferror(3)) is set, and errno is set indicate the
       error.

在你的情况下,scanf()可以返回0,1或EOF.

PS正如其他人所指出的那样,你在前面错过了一个&符号man:

NAME
       scanf,  fscanf, sscanf, vscanf, vsscanf, vfscanf 

       ...

RETURN VALUE
       These functions return the number of input items  successfully  matched
       and assigned, which can be fewer than provided for, or even zero in the
       event of an early matching failure.

       The value EOF is returned if the end of input is reached before  either
       the  first  successful conversion or a matching failure occurs.  EOF is
       also returned if a read error occurs, in which case the error indicator
       for  the  stream  (see ferror(3)) is set, and errno is set indicate the
       error.

没有&符号,代码的行为是不确定的.

Answer 2

来自scanf:

成功时,该函数返回成功读取的项目数.如果发生匹配故障,此计数可以匹配预期的读数或更少,甚至为零.如果在成功读取任何数据之前输入失败,则返回EOF.