Pop Operation on Stack in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if the stack is empty before popping.

DSA C

if (top == [1]) {
    printf("Stack Underflow\n");
}

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

A0

B-1

C1

Dtop

Attempts:

3 left

💡 Hint

Common Mistakes

Checking if top == -1 which is incorrect for this stack implementation.

Using top == 1 which means one element is present, so pop is possible.

The stack is empty when top is 0, so we check if top == 0 before popping.

2fill in blank

medium

Complete the code to pop the top element from the stack.

DSA C

int popped_element = stack[[1] - 1];
top--;
printf("Popped element: %d\n", popped_element);

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Atop

Btop + 1

Ctop - 1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using top instead of top - 1 causes out-of-bounds access.

Decrementing top before accessing stack causes wrong element to be popped.

The top element is at index top - 1, so we access stack[top - 1] before decrementing top.

3fill in blank

hard

Fix the error in the pop function to correctly update the top index.

DSA C

int pop() {
    if (top == 0) {
        printf("Stack Underflow\n");
        return -1;
    }
    return stack[[1]];
}

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

Atop - 1

B--top

Ctop

Dtop + 1

Attempts:

3 left

💡 Hint

Common Mistakes

Using top-- causes accessing stack[top] which is out of bounds.

Using top + 1 or top - 1 incorrectly changes the index.

Using --top decrements top first, then accesses the correct top element.

4fill in blank

hard

Fill both blanks to implement a safe pop function that returns the popped element or -1 if empty.

DSA C

int pop() {
    if (top == [1]) {
        return [2];
    }
    return stack[--top];
}

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

A0

B-1

C1

Dtop

Attempts:

3 left

💡 Hint

Common Mistakes

Returning 0 instead of -1 on empty stack.

Checking if top == 1 which is incorrect.

If top is 0, stack is empty, so return -1 to indicate underflow.

5fill in blank

hard

Fill all three blanks to print the stack elements after popping one element.

DSA C

pop();
for (int i = [1]; i [2] 0; i[3]) {
    printf("%d ", stack[i]);
}
printf("\n");

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

Atop - 1

B>=

Ctop

D--

E++

Attempts:

3 left

💡 Hint

Common Mistakes

Using ++ instead of -- causes infinite loop.

Starting loop at top instead of top - 1 misses last element.

Start from top - 1, go down to 0, decrementing i to print all elements after pop.