C Program to Check if a String is a Palindrome without using the Built-in Function

Code:

#include
#include

void main()
{
    char string[25], reverse_string[25] = {'\0'};
    int i, length = 0, flag = 0;

    printf("Enter a string \n");
    gets(string);
    /*  keep going through each character of the string till its end */
    for (i = 0; string[i] != '\0'; i++)
    {
        length++;
    }
    printf("The length of the string '%s' = %d\n", string, length);
    for (i = length - 1; i >= 0 ; i--)
    {
        reverse_string[length - i - 1] = string[i];
    }
   /*  Check if the string is a Palindrome */

    for (flag = 1, i = 0; i < length ; i++)
    {
        if (reverse_string[i] != string[i])
            flag = 0;
    }
    if (flag == 1)
       printf ("%s is a palindrome \n", string);
    else
       printf("%s is not a palindrome \n", string);
}

Output:

Enter a string
how  are you
The length of the string 'how  are you' = 12
how  are you is not a palindrome


Enter a string
madam
The length of the string 'madam' = 5
madam is a palindrome


Enter a string
mam
The length of the string 'mam' = 3
mam is a palindrome

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