When a stack is created using single array, we can not able to store large amount of data, thus this problem is rectified using more than one stack in the same array of sufficient array. This technique is called as Multiple Stack.
- Data Structure Multiple Stack
A single stack is sometime not sufficient to store large amount of data. To overcome this problem we can use multiple stack. For this, we have used a single array having more than one stack. The array is divided for multiple stacks.
Suppose, there is an array STACK[n] divided into two stack STACK A and STACK B, where n = 10.
STACK A expands from the left to right, i.e. from 0th element.
STACK B expands from the right to left, i.e, from 10th element.
The combined size of both STACK A and STACK B never exceed 10.
Multi STACK Program in C
The following program demonstrates Multiple Stack -
#include <stdio.h>
#include <malloc.h>
#define MAX 10
int stack[MAX], topA = -1, topB = MAX;
void push_stackA(int val)
{
if(topA == topB-1)
printf("\n STACK OVERFLOW");
else
{
topA+=1;
stack[topA] = val;
}
}
int pop_stackA()
{
int val;
if(topA == -1)
{
printf("\n STACK UNDERFLOW");
}
else
{
val = stack[topA];
topA--;
}
return val;
}
void display_stackA()
{
int i;
if(topA == -1)
printf("\n Empty STACK A");
else
{
for(i = topA;i >= 0;i--)
printf("\t %d",stack[i]);
}
}
void push_stackB(int val)
{
if(topB-1 == topA)
printf("\n STACK OVERFLOW");
else
{
topB-=1;
stack[topB] = val;
}
}
int pop_stackB()
{
int val;
if(topB == MAX)
{
printf("\n STACK UNDERFLOW");
}
else
{
val = stack[topB];
topB++;
}
}
void display_stackB()
{
int i;
if(topB == MAX)
printf("\n Empty STACK B");
else
{
for(i = topB; i < MAX;i++)
printf("\t %d",stack[i]);
}
}
int main()
{
int option, val;
do
{
printf("\n -----Menu----- ");
printf("\n Enter 1 to PUSH a element into STACK A");
printf("\n Enter 2 to PUSH a element into STACK B");
printf("\n Enter 3 to POP a element from STACK A");
printf("\n Enter 4 to POP a element from STACK B");
printf("\n Enter 5 to display the STACK A");
printf("\n Enter 6 to display the STACK B");
printf("\n Press 7 to exit");
printf("\n Enter your choice: ");
scanf("%d",&option);
switch(option)
{
case 1:
printf("\n Enter a value to PUSH on STACK A :");
scanf("%d",&val);
push_stackA(val);
break;
case 2:
printf("\n Enter the value to PUSH on STACK B:");
scanf("%d", &val);
push_stackB(val);
break;
case 3:
printf("\n The value POPPED from STACK A = %d", val);
pop_stackA();
break;
case 4:
printf("\n The value POPPED from STACK B = %d", val);
pop_stackB();
break;
case 5:
printf("\n The STACK A elements are :\n");
display_stackA();
break;
case 6:
printf("\n The STACK B elements are :\n");
display_stackB();
break;
}
}while(option != 7);
return 0;
}
Multiple stacks allow access to multiple values within a clock cycle. As an example, a machine that has simultaneous access to both a data stack and a return address stack can perform subroutine calls and returns in parallel with data operations.
