Call stack behavior - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a function named 'foo'.

C

void [1]() {
    // function body
}

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

Afoo

Bbar

Cmain

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different function name than 'foo'.

The function name should be 'foo' as requested.

2fill in blank

medium

Complete the code to call the function 'foo' inside 'main'.

C

int main() {
    [1]();
    return 0;
}

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

Amain

Bfoo

Cstart

Dbar

Attempts:

3 left

💡 Hint

Common Mistakes

Calling a function that is not defined or named differently.

To call the function 'foo', write 'foo();' inside main.

3fill in blank

hard

Fix the error in the recursive function call to 'countdown'.

C

void countdown(int n) {
    if (n == 0) return;
    printf("%d\n", n);
    [1](n - 1);
}

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

Acountdownn

Bcount_down

Ccount

Dcountdown

Attempts:

3 left

💡 Hint

Common Mistakes

Misspelling the function name in the recursive call.

The function calls itself by its exact name 'countdown' for recursion.

4fill in blank

hard

Fill both blanks to create a function that prints numbers from 1 to n using recursion.

C

void print_numbers(int [1]) {
    if ([2] == 0) return;
    print_numbers([2] - 1);
    printf("%d\n", [2]);
}

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

Anum

Bn

Ccount

Di

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names for parameter and condition.

The parameter name is 'n' and the base case checks if 'n' is zero.

5fill in blank

hard

Fill all three blanks to create a recursive factorial function.

C

int factorial(int [1]) {
    if ([2] <= 1) return 1;
    return [2] * factorial([3] - 1);
}

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

Anum

Bn

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing different variable names for the parameter and recursive call.

The parameter is named 'n'. The base case checks 'n'. The recursive call uses 'n - 1'.