C Language: memcmp function
(Compare Memory Blocks)
In the C Programming Language, the memcmp function returns a negative, zero, or positive integer depending on whether the first n characters of the object pointed to by s1 are less than, equal to, or greater than the first n characters of the object pointed to by s2.
Syntax
The syntax for the memcmp function in the C Language is:
int memcmp(const void *s1, const void *s2, size_t n);
Parameters or Arguments
- s1
- An array to compare.
- s2
- An array to compare.
- n
- The number of characters to compare.
Returns
The memcmp function returns an integer. The return values are as follows:
| Return Value | Explanation |
|---|---|
| 0 | s1 and s2 are equal |
| Negative integer | The stopping character in s1 was less than the stopping character in s2 |
| Positive integer | The stopping character in s1 was greater than the stopping character in s2 |
Required Header
In the C Language, the required header for the memcmp function is:
#include <string.h>
Applies To
In the C Language, the memcmp function can be used in the following versions:
- ANSI/ISO 9899-1990
memcmp Example
Let's look at an example to see how you would use the memcmp function in a C program:
/* Example using memcmp by TechOnTheNet.com */
#include <stdio.h>
#include <string.h>
int main(int argc, const char * argv[])
{
/* Create a place to store our results */
int result;
/* Create two arrays to hold our data */
char example1[50];
char example2[50];
/* Copy two strings into our data arrays
(These can be any data and do not have to be strings) */
strcpy(example1, "C memcmp at TechOnTheNet.com");
strcpy(example2, "C memcmp is a memory compare function");
/* Compare the two strings provided up to the first 9 characters */
result = memcmp(example1, example2, 9);
/* If the two arrays are the same say so */
if (result == 0) printf("Arrays are the same\n");
/* Compare the two strings provided up to the first 10 characters */
result = memcmp(example1, example2, 10);
/* If the first array is less than the second say so
(This is because the 'a' in the word 'at' is less than
the 'i' in the word 'is' */
if (result < 0) printf("Second array is less than the first\n");
return 0;
}
When compiled and run, this application will output:
Arrays are the same Second array is less than the first
Similar Functions
Other C functions that are similar to the memcmp function:
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