memcmp
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Header File
mem.h, string.h
Category
Memory and String Manipulation Routines, Inline Routines
Prototype
int memcmp(const void *s1, const void *s2, size_t n);
Description
Compares two blocks for a length of exactly n bytes.
memcmp
is available on UNIX System V systems.
memcmp
compares the first n bytes of the blocks s1 and s2 as unsigned chars.
Return Value
Because it compares bytes as unsigned chars, memcmp
returns a value that is
- < 0 if s1 is less than s2
- = 0 if s1 is the same as s2
- > 0 if s1 is greater than s2
For example,
memcmp("\xFF", "\x7F", 1)
returns a value greater than 0.
Note: If you are using the intrinsic version of these functions, the case of n = 0 will return NULL.
Example
#include <stdio.h> #include <string.h> int main(void) { char *buf1 = "aaa"; char *buf2 = "bbb"; char *buf3 = "ccc"; int stat; stat = memcmp(buf2, buf1, strlen(buf2)); if (stat > 0) printf("buffer 2 is greater than buffer 1\n"); else printf("buffer 2 is less than buffer 1\n"); stat = memcmp(buf2, buf3, strlen(buf2)); if (stat > 0) printf("buffer 2 is greater than buffer 3\n"); else printf("buffer 2 is less than buffer 3\n"); return 0; }
Portability
POSIX | Win32 | ANSI C | ANSI C++ |
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