Program on Array implementation of stack in C

 

# include< stdio.h>
# include< string.h>
# define size 3
int tos= -1;
/*this variable will keep track of the top of the stack */
int flag = 0;
/* this variable will determine whether push or pop will be granted. */
int stack[size];
/* array , within this array stack will grow and shrink. */
void push(int s[], int d)
{
if(tos==size-1)
{
/* this condition becomes true when the stack can not grow further */
flag=0;
}
else
{
flag = 1;
++tos;
s[tos] = d;
}
}
int pop(int s[])
{
int p;
if(tos == -1)
{
p = 0;
flag = 0;
}
else
{
flag = 1;
p = s[tos];
--tos;
}
return p;
}
void display(int s[])
{
int i;
if(tos == -1)
{
printf("\n Stack is empty");
}
else
{
for(i = tos; i >= 0; --i)
printf("\n %d", s[i] );
}
}
void main()
{
int data;
char choice;
int q = 0;
clrscr();
do
{
printf(" \nPush->i Pop->p Quit->q:");
printf("\nInput the choice : ");
do
{
choice = getchar();
choice =tolower(choice);
}while(strchr("ipq",choice)==NULL);
printf("Your choice is: %c",choice);
switch(choice)
{
case 'i' :
printf("\n Input the element to push:");
scanf("%d", &data);
push(stack, data);
if(flag)
{
printf("\n After inserting ");
display(stack);
if(tos == (size-1))
printf("\n Stack is full");
}
else
printf("\n capacity is exhausted");
break;
case 'p' :
data = pop(stack);
if(flag)
{
printf("\n Data is popped: %d", data);
printf("\n Rest data in stack is as follows:\n");
display(stack);
}
else
printf("\n No popping took place" );
break;
case 'q':
q = 1;
}
} while(!q);
getch();
}