C program to implement stack .

                  /* C program to implement stack  */

#include<stdio.h>
#define SIZE 5
int a[SIZE],top=-1;
void push()
{
 if(top==SIZE-1)
 {
  printf("\n Stack overflow");
 }
 else
   {
    printf("Enter a no. to push:");
    scanf("%d", &a[++top]);
    printf("Element pushed into stack:\n\n");
   }
}
void pop()
{
 if(top==-1)
 {
  printf("\n Stack underflow");
 }
 else
 {
  top--;
  printf("Element popped into stack is:%d", a[top+1]);
 }
}
void show()
{
  int i;
  if(top==-1)
  {
   printf("Stack is empty:\n");
  }
  else

   for(i=0; i<=top; i++)
   printf("%d", a[i]);

}
int main()
{
 int ch;

  do
  {
   printf(":::Stack operation:::\n");
   printf("1.push 2.pop 3.show 4.exit\n");
   printf("Enter your choice:");
   scanf("%d", &ch);
   switch(ch)
   {
    case 1: push(); break;
    case 2: pop(); break;
    case 3: show(); break;
    case 4: printf("Invalid choice..");
   }
  }while(ch!=4);
  return 0;
 }

* INPUT/OUTPUT:- *

:::Stack operation:::
1.push 2.pop 3.show 4.exit
Enter your choice:1
Enter a no. to push:56
Element pushed into stack:

:::Stack operation:::
1.push 2.pop 3.show 4.exit
Enter your choice:1
Enter a no. to push:85
Element pushed into stack:

:::Stack operation:::
1.push 2.pop 3.show 4.exit
Enter your choice:1
Enter a no. to push:33
Element pushed into stack:

:::Stack operation:::
1.push 2.pop 3.show 4.exit
Enter your choice:1
Enter a no. to push:55
Element pushed into stack:

:::Stack operation:::
1.push 2.pop 3.show 4.exit
Enter your choice:1
Enter a no. to push:89
Element pushed into stack:

:::Stack operation:::
1.push 2.pop 3.show 4.exit
Enter your choice:1
 Stack overflow

:::Stack operation:::
1.push 2.pop 3.show 4.exit
Enter your choice:3
56 85 33 55 89

:::Stack operation:::
1.push 2.pop 3.show 4.exit
Enter your choice:2
Element popped into stack is:89

:::Stack operation:::
1.push 2.pop 3.show 4.exit
Enter your choice:2
Element popped into stack is:55

:::Stack operation:::
1.push 2.pop 3.show 4.exit
Enter your choice:2
Element popped into stack is:33

:::Stack operation:::
1.push 2.pop 3.show 4.exit
Enter your choice:2
Element popped into stack is:85

:::Stack operation:::
1.push 2.pop 3.show 4.exit
Enter your choice:2
Element popped into stack is:56

:::Stack operation:::
1.push 2.pop 3.show 4.exit
Enter your choice:2
 Stack underflow

:::Stack operation:::
1.push 2.pop 3.show 4.exit
Enter your choice:2
 Stack underflow

:::Stack operation:::
1.push 2.pop 3.show 4.exit
Enter your choice:3
Stack is empty:

:::Stack operation:::
1.push 2.pop 3.show 4.exit
Enter your choice:4
Invalid choice..

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