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Qn-4.c

Problem Statement

Write a program to check a string is palindrome or not using user-defined function.

Metadata

Property Detail
Author Amit Dutta amitdutta4255@gmail.com
Date 06 Mar 2026
License MIT License (See the LICENSE file for details)
Difficulty Beginner (index: 2 / 10)

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Source Code

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

bool isPalindrome(char str[]);

int main() {
    char str[100];

    printf("Enter a string: ");
    fgets(str, sizeof(str), stdin);
    str[strcspn(str, "\n")] = '\0';
    if (isPalindrome(str)) {
        printf("\"%s\" is a palindrome.\n", str);
    } else {
        printf("\"%s\" is not a palindrome.\n", str);
    }
    return 0;
}

bool isPalindrome(char str[]) {
    int left = 0;
    int right = strlen(str) - 1;

    while (right > left) {
        if (tolower(str[left]) != tolower(str[right])) {
            return false; 
        }
        left++;
        right--;
    }
    return true; 
}

Explanation

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    You are explaining a C programming code to a beginner.

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    - Only use the given code. Do NOT assume anything not present.

    - Do NOT add extra examples.

    - Keep explanation clear and short.

    - If something is unclear, say "Not clear from code".

    - Follow the exact format below. Do NOT change headings.

    FORMAT:

    [START]

    ## What it does

    (Explain the overall purpose in 1-2 sentences)

    ## Step-by-step

    (Explain how the code works in steps, simple language)

    ## Key Concepts

    (List concepts like loop, condition, function, etc.)

    ## Notes

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    [END]

    CODE (Qn-4.c):

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

    bool isPalindrome(char str[]);

    int main() {
        char str[100];

        printf("Enter a string: ");
        fgets(str, sizeof(str), stdin);
        str[strcspn(str, "\n")] = '\0';
        if (isPalindrome(str)) {
            printf("\"%s\" is a palindrome.\n", str);
        } else {
            printf("\"%s\" is not a palindrome.\n", str);
        }
        return 0;
    }

    bool isPalindrome(char str[]) {
        int left = 0;
        int right = strlen(str) - 1;

        while (right > left) {
            if (tolower(str[left]) != tolower(str[right])) {
                return false; 
            }
            left++;
            right--;
        }
        return true; 
    }