Stack Concept and LIFO Principle in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a stack array of size 5.

DSA C

int stack[[1]];

Drag options to blanks, or click blank then click option'

A5

B7

C3

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Using a size other than 5.

Forgetting to specify the size.

The stack array size is 5 to hold 5 elements.

2fill in blank

medium

Complete the code to initialize the top of the stack to -1.

DSA C

int top = [1];

Drag options to blanks, or click blank then click option'

A1

B0

C-1

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Setting top to 0 which means stack has one element.

Using positive numbers initially.

Top is set to -1 to indicate the stack is empty initially.

3fill in blank

hard

Fix the error in the push function to correctly add an element to the stack.

DSA C

void push(int stack[], int *top, int value) {
    if (*top < 4) {
        *top = *top [1] 1;
        stack[*top] = value;
    }
}

Drag options to blanks, or click blank then click option'

A-

B+

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction which moves top backward.

Using multiplication or division which is incorrect here.

We add 1 to top to move to the next empty position before inserting.

4fill in blank

hard

Fill both blanks to correctly pop an element from the stack.

DSA C

int pop(int stack[], int *top) {
    int value = stack[*top];
    *top = *top [1] 1;
    return value;
}

Drag options to blanks, or click blank then click option'

A/

B+

C*

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition which moves top forward incorrectly.

Using multiplication or division which is invalid here.

We subtract 1 from top to move down after popping the element.

5fill in blank

hard

Fill all three blanks to check if the stack is empty and print a message.

DSA C

if (top [1] [2]) {
    printf("Stack is [3]\n");
}

Drag options to blanks, or click blank then click option'

A==

B!=

C-1

Dempty

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' instead of '=='.

Comparing top with 0 instead of -1.

Printing wrong message.

We check if top equals -1 to know stack is empty and print 'empty'.