DS lab program-4 (stack operation)

#include

#include

#define MAX 20

#define TRUE 1

#define FALSE 0

void push();

void display();

struct stack /* stack declarations */

{

int top,items[MAX];

}s;

main()

{

int i,n;

int choice,x;

clrscr();

s.top=-1;

while(1)

{

printf("\n1.PUSH\n2.POP\n3.DISPLAY\n4.TOPTEST\n");

printf("\n enter your choice\n");

scanf("%d",&choice);

switch(choice)

{

case 1:

printf("\nenter the values of n:");

scanf("%d",&n);

printf("\n enter the items");

for(i=0;i

{

scanf("%d",&x);

push(&s,x);

}

printf(" the stack items are:\n");

display(&s);

break;

case 2:

x=pop(&s);

printf("\n the value of x=%d\n",x);

break;

case 3:

display(&s);

break;

case 4:

x=toptest(&s);

printf("\n The top most item is %d\n",x);

break;

default:

printf("\n Invalid Entry");

getch();

exit(1);

}

}

getch();

}

/* function to push items to stack */

void push(struct stack *ps,int y)

{

if(ps->top==MAX-1)

{

printf("\n stack overflow");

getch();

exit(1);

}

else

ps->items[++(ps->top)]=y;

}

/* function to pop items from stack */

int pop(struct stack *ps)

{

int x;

if(empty(ps))

{

printf("\n stack underflow");

getch();

exit(1);

}

else

x=ps->items[ps->top--];

return(x);

}

/* function to check whether stack is empty */

int empty(struct stack *p)

{

if(p->top==-1)

return(TRUE);

else

return(FALSE);

}

/* function to display stack items */

void display(struct stack *ps)

{

int i,x;

for(i=ps->top;i>=0;i--)

{

x=ps->items[i];

printf("\n %d",x);

}

printf("\n");

}

/* fuction to check the top of stack */

int toptest(struct stack *ps)

{

int x;

if (empty(ps))

{

printf("\n Underflow");

getch();

exit(1);

}

else

{

x=ps->items[ps->top];

return(x);

}

}