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C Program to Check String is Palindrome using Stack

C Program to Check String is Palindrome using Stack

This is a C Program to identify whether the string is palindrome or not using stack.

- Take a string as input.
- Store the string in the stack array.
- Check whether the string is palindrome or not.

    #include <stdio.h>

    #include <stdlib.h>

    #include <string.h>

    #define MAX 50

    int top = -1, front = 0;

    int stack[MAX];

    void push(char);

    void pop();

    void main()

    {

        int j, choice;

        char s[MAX], b;

        while (1)

        {

            printf("1-enter string\n2-exit\n");

            printf("enter your choice\n");

            scanf("%d", &choice);

            switch (choice)

            {

            case 1:

                printf("Enter the String\n");

                scanf("%s", s);

                for (j = 0;s[j] != '\0';j++)

                {

                    b = s[j];

                    push(b);

                }

                for (j = 0;j < (strlen(s) / 2);j++)

                {

                    if (stack[top] == stack[front])

                    {

                        pop();

                        front++;

                    }

                    else

                    {

                        printf("%s is not a palindrome\n", s);

                        break; 

                    }

                }

                if ((strlen(s) / 2)  =  =  front)

                    printf("%s is palindrome\n",  s);

                front  =  0;

                top  =  -1;

                break;

            case 2:

                exit(0);

            default:

                printf("enter correct choice\n");

            }

        }

    }

    /* to push a character into stack */

    void push(char a)

    {

        top++;

        stack[top]  =  a;

    }

    /* to delete an element in stack */

    void pop()

    {

        top--;

    }

- Take a string as input and store it in the array s[].
- Load each character of the array s[] into the array stack[].
- Use variables front and top to represent the last and top element of the array stack[].
- Using for loop compare the top and last element of the array stack[]. If they are equal, then delete the top element, increment the variable front by 1 and compare again.
- If they are not equal, then print the output as "It is not a palindrome".
- Compare the elements in the steps 4-5 upto the middle element of the array stack[].
- If every characters of the array is equal, then it is a paliandrome.