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linux 下c函數strcmp的返回值疑問?

←手機掃碼閱讀     火星人 @ 2014-03-26 , reply:0

linux 下c函數strcmp的返回值疑問?
strcmp函數解釋:
NAME
strcmp, strncmp - compare two strings

SYNOPSIS
#include

int strcmp(const char *s1, const char *s2);

int strncmp(const char *s1, const char *s2, size_t n);

DESCRIPTION
The strcmp() function compares the two strings s1 and s2. It returns an integer less than, equal to, or greater than
zero if s1 is found, respectively, to be less than, to match, or be greater than s2.

The strncmp() function is similar, except it only compares the first (at most) n characters of s1 and s2.

RETURN VALUE
The strcmp() and strncmp() functions return an integer less than, equal to, or greater than zero if s1 (or the first n
bytes thereof) is found, respectively, to be less than, to match, or be greater than s2.

CONFORMING TO
SVr4, 4.3BSD, C89, C99.

SEE ALSO
bcmp(3), memcmp(3), strcasecmp(3), strcoll(3), strncasecmp(3), wcscmp(3), wcsncmp(3)

返回值是整型,那麼,當第一個參數const char *s1是空指針,即為NULL時,返回值應該是多少啊?
我等於NULL,結果編譯時,報:warning: comparison between pointer and integer
難道等於什麼?????


請高手賜教,謝謝!!

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