memcmp() — Compare bytes
Standards
| Standards / Extensions | C or C++ | Dependencies |
|---|---|---|
ISO C
XPG4 XPG4.2 C99 Single UNIX Specification, Version 3 |
both |
Format
#include <string.h>
int memcmp(const void *buf1, const void *buf2, size_t count);General description
The memcmp() built-in function compares the first count bytes of buf1 and buf2.
The relation is determined by the sign of the difference between the values of the leftmost first pair of bytes that differ. The values depend on EBCDIC encoding. This function is not locale sensitive.
Returned value
Indicates the relationship
between buf1 and buf2 as
follows:
- Value
- Meaning
- < 0
- The contents of the buffer pointed to by buf1 less than the contents of the buffer pointed to by buf2
- = 0
- The contents of the buffer pointed to by buf1 identical to the contents of the buffer pointed to by buf2
- > 0
- The contents of the buffer pointed to by buf1 greater than the contents of the buffer pointed to by buf2
Example
CELEBM12
/* CELEBM12
This example compares first and second arguments passed to
main to determine which, if either, is greater.
*/
#include <stdio.h>
#include <string.h>
int main(int argc, char ** argv)
{
int len;
int result;
if ( argc != 3 )
{
printf( "Usage: %s string1 string2\n", argv[0] );
}
else
{
/* Determine the length to be used for comparison */
if (strlen( argv[1] ) < strlen( argv[2] ))
len = strlen( argv[1] );
else
len = strlen( argv[2] );
result = memcmp( argv[1], argv[2], len );
printf( "When the first %i characters are compared,\n", len );
if ( result == 0 )
printf( "\"%s\" is identical to \"%s\"\n", argv[1], argv[2] );
else if ( result < 0 )
printf( "\"%s\" is less than \"%s\"\n", argv[1], argv[2] );
else
printf( "\"%s\" is greater than \"%s\"\n", argv[1], argv[2] );
}
}
Output
If the program is passed
the arguments firststring and secondstring,
you would obtain following:
When the first 11 characters are compared,
“firststring” is less than “secondstring”