String Reversal using Stack

9. Program to perform string reversal using stack?

Algorithm

Globally,Declare variables top=-1,count=20,stack[30];and define MAX as 10.

Step 1:Start

Step 2:Declare array x[20].

Step 3:Input the string.

Step 4:Read the string,x.

Step 5:Call the function,push(x).

Step 6:Call the function,pop().

Step 7:Stop.

Function push(char x[])

Step 1:Declare variable i=o.

Step 2:If top=MAX-1 then

                   2.1)Print Stack Overflow.

Step 3:Else

                   3.1)while(x[i]!=’\0’) repeat steps a to d.

                             a)Increment top by 1.

                             b)Assign stack[top]=x[i]

                             c)Increment i by 1.

                             d)Increment count by 1.

                   3.2)End while.

Step 4:End if.

Step 5:Return.

Function pop()

Step 1:Declare variable i.

Step 2:If top=-1 then

                   2.1)Print Stack Underflow.

Step 3:Else

                   3.1)while(i>0) repeat steps a to c.

                             a)Print the character at the top of the stack,stack[top].                                    

                             b)Decrement i by 1.

                             c)Decrement top by 1.

                   3.2)End while.

Step 4:End if.

Step 5:Return.

Program

#include<stdio.h>

#include<conio.h>

#define MAX 10

char stack[30];

int top=-1, count=20;

void push(char c[]);

void pop();

void main()

          {

          char x[20];

          clrscr();

          printf("Enter the string:\t");

          gets(x);

          push(x);

          pop();

          getch();

          }

void push(char x[])

          {

          int i=0;

          if(top==MAX-1)

                   printf("overflow");

          else

                   {

                   while(x[i]!='\0')

                             {

                             top++;

                             stack[top]=x[i];

                             i++;

                             count++;

                             }

                   }

          }

void pop()

          {

          int i;

          if(top==-1)

                   {

                   printf("Stack Underflow");

                   }

          else

                   {

                   i=count;

                   printf(“The reversed string is ”);

                   while(i>0)

                             {

                             printf("%c",stack[top]);

                             i--;

                             top--;

                             }

                   }

          }

Output

Enter the string               PROGRAMMING

The reversed string is      GNIMMARGORP