String Comparison in C

String Comparison in C. String comparison is a common operation in programming, String comparison is used to check whether two strings are equal or not. In the C language, comparing strings involves checking each character in the String to ensure the match. In this article, we will write a C program for String comparison.

Understanding String Comparison in C

In C, strings are the arrays of characters(char data type) terminated by a null character(‘\0’). To compare to strings, we need to examine each corresponding character in both strings until we find a mismatch or reach the end of either string. The comparison is case sensitive, that is upper case and lower case characters are written as distinct.

C Program for String Comparison

Let’s write a simple C program that compares strings by using a custom string comparison function as well as by using the standard library function ‘strcmp()’.

#include <stdio.h>
#include <string.h>
// Function to perform string comparision
int customStrcmp(char *str1, char *str2)
{
    while (*str1 != '\0' && *str2 != '\0' && *str1 == *str2)
    {
        str1++;
        str2++;
    }
    return (*str1 - *str2);
}
void main()
{
    char strA[] = "Gang For Code";
    char strB[] = "Gang For Code";
    // String comparision by using strcmp()
    if (strcmp(strA, strB) == 0)
    {
        printf(" By using strcmp()- both strings are equal\n");
    }
    else
    {
        printf(" By using strcmp()- both strings are not equal\n");
    }
    // string comparision by using custom function
    if (customStrcmp(strA, strB) == 0)
    {
        printf(" By using custom function- both strings are equal\n");
    }
    else
    {
        printf(" By using custom function- both strings are not equal\n");
    }
}

Output

Explanation of C Program for String Comparison

• The function customStrcmp iterates through the characters of both strings until a mismatch is found or the end of either string is reached. It returns the difference between the ASCII values of the mismatched characters.
• Inside the main function, there are two strings declared- strA, and strB.
• We used a standard library function strcmp() to compare the strings and print the result.
• We also use the custom function customStrcmp() to compare the strings and print the result.

Happy Coding

See Also

• Basic Structure of a C Program
• Relational Operators in C