Program to check string is Palindrome or Not. in C | Programmerdouts

Practice Program

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Program to check string is Palindrome or Not.

A palindrome is a word, number, phrase, or other sequence of characters which reads the same backward as forward, such as madam or racecar or the number 10801.

Solution:

void main()
{
    int result ,i;

    char s1[20],s2[20];


    printf("Enter the string: ");
    gets(s1);


    strcpy(s2,s1);

 int l = strlen(s1);//storing length of string in variable l.


 char ch;
    for(i=0; i<(l/2); i++)
    {
        ch = s1[i];  //at every iteration we swapping character at i index
        s1[i] = s1[(l-1)-i]; //with character at index ((l-1)-i)
        s1[(l-1)-i] = ch;
    }

    if(strcmp(s1,s2) == 0)
    {
        printf("String is palindrome");
    }
    else
        printf("String is not palindrome.");

}

Output1

Enter the string: programmerdouts

String is not palindrome

Output2

Enter the string: LeveL

String is palindrome

Output3

Enter the string: racecar

String is palindrome

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defining a function 'is_palindrome' which will check string is palindrome or not

int is_palindrome(char s1[])
{
     int l = strlen(s1);//storing length of string in variable l.
 int i;
 char s2[20];


 strcpy(s2,s1);

 char ch;
    for(i=0; i<(l/2); i++)
    {
        ch = s1[i];  //at every iteration we swapping character at i index
        s1[i] = s1[(l-1)-i]; //with character at index ((l-1)-i)
        s1[(l-1)-i] = ch;
    }

    if(strcmp(s1,s2) == 0)
    {
        return 1;
    }
    else
        return 0;

}

Using above define function 'is_palindrome()':

void main()
{ int result;
    char s[20] = "level";

    result  = is_palindrome(s);

    if(result == 1)
    {
        printf("String is palindrome");
    }
    else
        printf("String is not palindrome.");

}

Output1

String is palindrome

Using above define function 'is_palindrome()':

void main()
{ int result;
    char s[20] = "doubts";

    result  = is_palindrome(s);

    if(result == 1)
    {
        printf("String is palindrome");
    }
    else
        printf("String is not palindrome.");

}

Output2

String is not palindrome

Using above define function 'is_palindrome()':

void main()
{ int result;
    char s[20] = "programmer";

    result  = is_palindrome(s);

    if(result == 1)
    {
        printf("String is palindrome");
    }
    else
        printf("String is not palindrome.");

}

Output3

String is not palindrome

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