C strcmp() Function

The strcmp() function in C is used to compare two strings. It compares each character of the strings and returns a value based on the result of the comparison. The function is defined in the string.h library.

Syntax of strcmp()

The syntax of the strcmp() function is as follows:

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

The function takes two arguments:

• str1: A pointer to the first string to be compared.
• str2: A pointer to the second string to be compared.

The function returns:

• A value < 0 if str1 is less than str2.
• A value > 0 if str1 is greater than str2.
• 0 if both strings are equal.

Example of strcmp() Function

Here is an example that demonstrates how the strcmp() function works:

                        
#include <stdio.h>
#include <string.h>
int main() 
{
    char str1[] = "Hello";
    char str2[] = "World";
    char str3[] = "Hello";
    
    int result1 = strcmp(str1, str2);  // Comparing "Hello" with "World"
    int result2 = strcmp(str1, str3);  // Comparing "Hello" with "Hello"
    
    // Output the results of comparisons
    printf("Comparison Result 1: %d\n", result1);  // Output will be negative
    printf("Comparison Result 2: %d\n", result2);  // Output will be 0
                   
    return 0;
}
                        
                    

Explanation of the Example

In this example:

• strcmp(str1, str2) compares the strings "Hello" and "World". Since "Hello" comes before "World" lexicographically, the function returns a negative value (e.g., -1).
• strcmp(str1, str3) compares the strings "Hello" and "Hello". Since the strings are identical, the function returns 0.

Important Notes

• The strcmp() function is case-sensitive. This means that uppercase and lowercase characters are treated as different (e.g., 'A' < 'a').
• It's essential to ensure that the strings being compared are properly null-terminated, as the function relies on the null character '0' to determine the end of the string.
• The comparison is done lexicographically (like dictionary order), which means that the function compares the ASCII values of corresponding characters in the strings.