How is the strcmp function used in C language?

2 years ago
Noah Thompson
2 minutes

The strcmp function in C language is used for comparing the size of two strings.

The function prototype is:

int strcmp(const char *str1, const char *str2);

The parameters str1 and str2 represent two strings to be compared. The function returns an integer value with several possible outcomes.

  1. Return 0 if str1 is equal to str2.
  2. Return a negative number if str1 is less than str2.
  3. If str1 is greater than str2, return a positive number.

The strcmp function compares the corresponding characters of two strings in dictionary order until it encounters a different character or reaches the end of both strings. During comparison, it compares the ASCII values of the characters in sequence.

For example:

#include <stdio.h>
#include <string.h>

int main() {
    char str1[] = "hello";
    char str2[] = "world";
    int result = strcmp(str1, str2);
    
    if (result == 0) {
        printf("str1 equals to str2\n");
    } else if (result < 0) {
        printf("str1 is less than str2\n");
    } else {
        printf("str1 is greater than str2\n");
    }
    
    return 0;
}

The output result is:

str1 is less than str2

In the example above, the comparison was made between the two strings “hello” and “world”. Because “hello” is smaller than “world” in lexicographical order, a negative number was returned.

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