Implementing a Queue Using Stacks: Step-by-Step Guide

Implement queue using stack

Function to create a queue

 /*Function to create a queue*/
void create()
{
    top1 = top2 = -1;
}

Function to push the element on to the stack

/*Function to push the element on to the stack*/
void push1(int data)
{
    st1[++top1] = data;
}

Function to pop the element from the stack

/*Function to pop the element from the stack*/
int pop1()
{
    return(st1[top1--]);
}

Function to push an element on to stack

/*Function to push an element on to stack*/
void push2(int data)
{
    st2[++top2] = data;
}

Function to pop an element from th stack

/*Function to pop an element from th stack*/
 
int pop2()
{
    return(st2[top2--]);
}

Function to add an element into the queue using stack

/*Function to add an element into the queue using stack*/
void enqueue()
{
    int data, i;
 
    printf("Enter data into queue");
    scanf("%d", &data);
    push1(data);
    count++;
}

Function to delete an element from the queue using stack

/*Function to delete an element from the queue using stack*/
 
void dequeue()
{
    int i;
 
    for (i = 0;i <= count;i++)
    {
        push2(pop1());
    }
    pop2();
    count--;
    for (i = 0;i <= count;i++)
    {
        push1(pop2());
    }
}

Function to display the elements in the stack

/*Function to display the elements in the stack*/
 
void display()
{
    int i;
 
    for (i = 0;i <= top1;i++)
    {
        printf(" %d ", st1[i]);
    }
}

C Program to Implement Queues using Stacks

 /*
 * C Program to Implement Queues using Stacks
 */
#include 
#include 
 
void push1(int);
void push2(int);
int pop1();
int pop2();
void enqueue();
void dequeue();
void display();
void create();
 
int st1[100], st2[100];
int top1 = -1, top2 = -1;
int count = 0;
 
void main()
{
    int ch;
 
    printf("\n1 - Enqueue element into queue: ");
    printf("\n2 - Dequeu element from queue: ");
    printf("\n3 - Display from queue: ");
    printf("\n4 - Exit");
    create();
    while (1)
    {
        printf("\nEnter choice: ");
        scanf("%d", &ch);
        switch (ch)
        {
        case 1:
            enqueue();
            break;
        case 2:
            dequeue();
            break;
        case 3:
            display();
            break;
        case 4:
            exit(0);
        default:
            printf("Wrong choice");
        }
    }
}
 
/*Function to create a queue*/
void create()
{
    top1 = top2 = -1;
}
 
/*Function to push the element on to the stack*/
void push1(int data)
{
    st1[++top1] = data;
}
 
/*Function to pop the element from the stack*/
int pop1()
{
    return(st1[top1--]);
}
 
/*Function to push an element on to stack*/
void push2(int data)
{
    st2[++top2] = data;
}
 
/*Function to pop an element from th stack*/
 
int pop2()
{
    return(st2[top2--]);
}
 
/*Function to add an element into the queue using stack*/
void enqueue()
{
    int data, i;
 
    printf("Enter data into queue: ");
    scanf("%d", &data);
    push1(data);
    count++;
}
 
/*Function to delete an element from the queue using stack*/
 
void dequeue()
{
    int i;
 
    for (i = 0;i <= count;i++)
    {
        push2(pop1());
    }
    pop2();
    count--;
    for (i = 0;i <= count;i++)
    {
        push1(pop2());
    }
}
 
/*Function to display the elements in the stack*/
 
void display()
{
    int i;
 
    for (i = 0;i <= top1;i++)
    {
        printf(" %d ", st1[i]);
    }
}

Output:

 
1 - Enqueue element into queue:
2 - Dequeu element from queue:
3 - Display from queue:
4 - Exit
Enter choice: 1
Enter data into queue: 10

Enter choice: 1
Enter data into queue: 12

Enter choice: 3
 10  12
Enter choice: 2

Enter choice: 3
 12
Enter choice: 4
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