Programming Example

C Program to Check whether the Given String is a Palindrome

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💻 Practical Program

📘 Step by Step Learning

Palindrome is a string, which when read in both forward and backward way is same.

Program Code

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

int main(){
    char string[20];
    int i, length;
    int flag = 0;
    
    printf("Enter a string:");
    scanf("%s", string);
    
    length = strlen(string);
    
    for(i=0;i < length ;i++){
        if(string[i] != string[length-i-1]){
            flag = 1;
            break;
   }
}
    
    if (flag) {
        printf("%s is not a palindrome\n", string);
    }    
    else {
        printf("%s is a palindrome\n", string);
    }
    return 0;
}

Output

<b>Output 1</b>
Enter a string:roor
roor is a palindrome
Press any key to continue . . .

<b>Output 2</b>
Enter a string:rum
rum is not a palindrome
Press any key to continue . . .

Explanation

To check if a string is a palindrome or not, a string needs to be compared with the reverse of itself.

Consider a palindrome string: radar,

---------------------------
index: 0 1 2 3 4

value: r a d a r
---------------------------

Palindrome String

To compare it with the reverse of itself, the following logic is used:

0th character in the char array, string1 is same as 4th character in the same string.
1st character is same as 3rd character.
2nd character is same as 2nd character.
. . . .
ith character is same as 'length-i-1'th character.
If any one of the above condition fails, flag is set to true(1), which implies that the string is not a palindrome.
By default, the value of flag is false(0). Hence, if all the conditions are satisfied, the string is a palindrome.

How to learn from this program

First read the algorithm, then study the program code line by line. After that, compare the code with the output and finally go through the explanation. This approach helps learners understand both the logic and the implementation properly.

Practice suggestion

After understanding this example, try to rewrite the same program without looking at the code. Then change some values or logic and run it again. This helps improve confidence and keeps learners engaged on the page for longer.