C program to implement stack using array

C program to implement stack using array - Source code

struct stack
{
    int stk[MAXSIZE];
    int top;
};
typedef struct stack STACK;
STACK s;
 
void push(void);
int  pop(void);
void display(void);
 
void main ()
{
    int c;
    int option = 1;
    s.top = -1;
 
    printf ("STACK OPERATION\n");
    while (option)
    {
        printf ("------------------------------------------\n");
        printf ("      1    -->    PUSH OPERATION               \n");
        printf ("      2    -->    POP OPERATION               \n");
        printf ("      3    -->    DISPLAY ELEMENTS               \n");
        printf ("      4    -->    EXIT           \n");
        printf ("------------------------------------------\n");
 
        printf ("Enter your choice\n");
        scanf    ("%d", &c);
        switch (c)
        {
        case 1:
            push();
            break;
        case 2:
            pop();
            break;
        case 3:
            display();
            break;
        case 4:
            return;
        }
        fflush (stdin);
        printf ("Do you want to continue(Type 0 or 1)?\n");
        scanf    ("%d", &option);
    }
}
/*  Function to add an element to the stack */
void push ()
{
    int n;
    if (s.top == (MAXSIZE - 1))
    {
        printf ("Stack is Full\n");
        return;
    }
    else
    {
        printf ("Enter the element to be pushed to stack\n");
        scanf ("%d", &n);
        s.top = s.top + 1;
        s.stk[s.top] = n;
    }
    return;
}
/*  Function to delete an element from the stack */
int pop ()
{
    int n;
    if (s.top == - 1)
    {
        printf ("Stack is Empty\n");
        return (s.top);
    }
    else
    {
        n = s.stk[s.top];
        printf ("poped element is %d\n", s.stk[s.top]);
        s.top = s.top - 1;
    }
    return(n);
}
/*  Function to display the status of the stack */
void display ()
{
    int i;
    if (s.top == -1)
    {
        printf ("Stack is empty\n");
        return;
    }
    else
    {
        printf ("\n The status of the stack is \n");
        for (i = s.top; i >= 0; i--)
        {
            printf ("%d\n", s.stk[i]);
        }
    }
    printf ("\n");
}

Program Output

STACK OPERATION
------------------------------------------
      1    -->    PUSH OPERATION
      2    -->    POP OPERATION
      3    -->    DISPLAY ELEMENTS
      4    -->    EXIT
------------------------------------------
Enter your choice
1
Enter the element to be pushed to stack
10
Do you want to continue(Type 0 or 1)?
1
------------------------------------------
      1    -->    PUSH OPERATION
      2    -->    POP OPERATION
      3    -->    DISPLAY ELEMENTS
      4    -->    EXIT
------------------------------------------
Enter your choice
1
Enter the element to be pushed to stack
20
Do you want to continue(Type 0 or 1)?
1
------------------------------------------
      1    -->    PUSH OPERATION
      2    -->    POP OPERATION
      3    -->    DISPLAY ELEMENTS
      4    -->    EXIT
------------------------------------------
Enter your choice
1
Enter the element to be pushed to stack
30
Do you want to continue(Type 0 or 1)?
1
------------------------------------------
      1    -->    PUSH OPERATION
      2    -->    POP OPERATION
      3    -->    DISPLAY ELEMENTS
      4    -->    EXIT
------------------------------------------
Enter your choice
2
poped element is 30
Do you want to continue(Type 0 or 1)?
1
------------------------------------------
      1    -->    PUSH OPERATION
      2    -->    POP OPERATION
      3    -->    DISPLAY ELEMENTS
      4    -->    EXIT
------------------------------------------
Enter your choice
3

 The status of the stack is
20
10

Do you want to continue(Type 0 or 1)?

Program Explanation

1. Ask the user for the operation like push, pop, display and exit. Use the variable top to represent the top of the stack.

Initialize the top of stack to -1.

2. According to the option entered, access its respective function using switch statement.

3. In the function push(), firstly check if the stack is full. If it is, then print the output as “Stack is Full”. Otherwise take the number to be inserted as input and store it in the variable n. Copy the number to the array stk[] and increment the variable top by 1.

4. In the function pop(), firstly check if the stack is empty. If it is, then print the output as “Stack is Empty”. Otherwise print the top most element of the array stk[] and decrement the variable top by 1.

5. In the function display(), using for loop print all the elements of the array.

6. Keep repeating the above process until the user enters the 0 to exit the program.