How to check Palindrome

Check if a string is palindrome or not is one of most common question we encountered during our basic days.

Let's Solve this problem with a Naive but efficient approach in this case.

Pseudocode :

1. i=0, j=n
2. while i < j:
3.    check if i'th element is not equal to j'th
4.      then return False 
5.   else i++,j--
6. loop end
7. return True

Source Code in C:

We implemented both versions of palindrome check using for loop and while loop.

1. #include<stdio.h>
3. int isPalindrome(char arr[],int size){
4.     //Using for loop
5.     int i,j;
6.     for(i=0,j=size-1;i<j;i++,j--){
7.         if(arr[i] != arr[j]){
8.             return 0;
9.         }
10.     }
11.     return 1;
12. }
14. int isPalindrome2(char arr[],int size){
15.     //using While loop
16.     int i,j;
17.     i=0;
18.     j=size-1;
19.     while(i<j){
20.         if(arr[i] != arr[j]){
21.             return 0;
22.         }
23.         else{
24.             i++;
25.             j--;
26.         }
27.     }
28.     return 1;
29. }
31. int main(){
32.     char arr[4]={"abba"};
33.     char arr2[5]={"abvba"};
34.    
35.     if(isPalindrome(arr,4)){
36.         printf("\n%s : is a Palindrome",arr);
37.     }else{
38.         printf("\nIt is NOT a Palindrome");
39.     }
40.    
41.     if(isPalindrome2(arr2,5)){
42.         printf("\n%s : is a Palindrome",arr2);
43.     }else{
44.         printf("\nIt is NOT a Palindrome");
45.     }
46. }

Output:

isPalindrome