Unit 4: Functions - Practice Quiz

1 Which of the following is the correct syntax for a function definition in C?

2 What are the two main parts of a function definition in C?

3 Functions like printf() and scanf() are examples of which type of functions?

4 A function written by the programmer to perform a specific task is called a:

5 Which header file must be included to use the sqrt() function in C?

6 A variable declared inside a function is known as a:

7 A global variable in C is accessible:

8 Where should a global variable be declared in a C program?

9 Which of the following correctly declares a pointer to an integer?

10 What does a pointer variable store?

11 Which operator is used to get the address of a variable when initializing a pointer?

12 Given int x = 5; int *p = &x;, what does p hold?

13 Which operator is used to access the value stored at the address a pointer points to?

14 If int x = 10; int *p = &x;, what is the value of *p?

15 In call by value, changes made to the parameters inside the function:

16 Which method allows a function to modify the caller's original variables?

17 When passing arguments by address, what is actually passed to the function?

18 Recursion is a process in which a function:

19 What is essential in every recursive function to prevent infinite calls?

20 Which of the following is a standard string library function in C?

21 Consider the following function definition:

int compute(int a, int b) {
    return a * b + a;
}

22 Which of the following correctly describes the components of a C function definition?

23 Which statement best distinguishes a user-defined function from a predefined (library) function in C?

24 To use the pow() function in a C program, which header file must be included?

25 What is the output of the following program?

#include <stdio.h>
int x = 10;
void show() {
    int x = 20;
    printf("%d", x);
}
int main() {
    show();
    return 0;
}

26 Which statement about local and global scope in C is correct?

27 What is the output of this program?

#include <stdio.h>
int count = 5;
void update() {
    count = count + 10;
}
int main() {
    update();
    printf("%d", count);
    return 0;
}

28 Given the declarations int a = 25; int *p = &a;, what does *p evaluate to?

29 What is the output of the following code?

#include <stdio.h>
int main() {
    int x = 7;
    int *p = &x;
    *p = *p + 3;
    printf("%d", x);
    return 0;
}

30 Which of the following correctly declares a pointer to an integer and initializes it with the address of variable n?

31 What is the output of the following program?

#include <stdio.h>
void change(int a) {
    a = a + 5;
}
int main() {
    int x = 10;
    change(x);
    printf("%d", x);
    return 0;
}

32 What is the output of the following program?

#include <stdio.h>
void change(int *a) {
    *a = *a + 5;
}
int main() {
    int x = 10;
    change(&x);
    printf("%d", x);
    return 0;
}

33 Which technique should be used to write a swap function that successfully exchanges the values of two variables from the caller?

34 What does the following recursive function return for fun(4)?

int fun(int n) {
    if (n == 0) return 0;
    return n + fun(n - 1);
}

35 What is the output of fact(5) for the following function?

int fact(int n) {
    if (n <= 1) return 1;
    return n * fact(n - 1);
}

36 What happens if a recursive function does not have a proper base case?

37 For the recursive function below, how many times is display called (including the initial call) when invoked as display(3)?

void display(int n) {
    if (n == 0) return;
    printf("%d", n);
    display(n - 1);
}

38 Which library function is used to determine the length of a string (excluding the null terminator) in C?

39 What is the return value of sqrt(16.0) from the math library?

40 Which library function converts a string such as "123" into its integer equivalent 123?

41 Consider the following function:

int f(int n) {
    if (n == 0) return 0;
    return n + f(n - 1);
}

42 What does the following program print?

#include <stdio.h>
void swap(int *a, int b) {
    int t = *a; *a = b; b = t;
}
int main() {
    int x = 3, y = 7;
    swap(&x, y);
    printf("%d %d", x, y);
}

43 What is the output of this program?

#include <stdio.h>
int x = 10;
void f() { x += 5; }
int main() {
    int x = 20;
    f();
    { int x = 30; printf("%d ", x); }
    printf("%d", x);
}

44 Given int a[] = {10, 20, 30, 40}; int *p = a + 1;, what is the value of *(p + 1) + *(a + 2)?

45 What does mystery(4) return?

int mystery(int n) {
    if (n <= 1) return 1;
    return mystery(n - 1) + mystery(n - 2);
}

46 What is printed by the following code?

#include <stdio.h>
int main() {
    int x = 5;
    int *p = &x;
    int **q = &p;
    **q = **q + 10;
    printf("%d", x);
}

47 What is the output of this program using a static local variable?

#include <stdio.h>
int counter() {
    static int c = 0;
    c++;
    return c;
}
int main() {
    printf("%d%d%d", counter(), counter(), counter());
}

48 What is the output?

#include <stdio.h>
void change(int *p) {
    p = p + 1;
    *p = 99;
}
int main() {
    int a[3] = {1, 2, 3};
    change(a);
    printf("%d %d %d", a[0], a[1], a[2]);
}

49 What does the following code print?

#include <stdio.h>
#include <string.h>
int main() {
    char s[20] = "Hello";
    strcat(s, "World");
    printf("%zu", strlen(s));
}

50 For the function below, what is f(6)?

int f(int n) {
    if (n == 0) return 1;
    if (n % 2 == 0) return f(n - 1);
    return 2 * f(n - 1);
}

51 In C, what happens if a function is called before any declaration or definition is visible, and it returns a double, but is implicitly assumed to return int?

52 Which statement best distinguishes a predefined (library) function from a user-defined function in C?

53 Which declaration correctly defines p as a pointer to a function that takes an int and returns an int?

54 How many times is f called in total (including the initial call) when f(3) runs?

void f(int n) {
    if (n <= 0) return;
    f(n - 1);
    f(n - 1);
}

55 What is the output?

#include <stdio.h>
void modify(int *pp) {
    static int val = 100;
    pp = &val;
    *pp = 200;
}
int main() {
    int a = 5;
    int *p = &a;
    modify(p);
    printf("%d", *p);
}

56 What does this program output?

#include <stdio.h>
int x = 1;
int f() { return x; }
int main() {
    int x = 2;
    { extern int x; printf("%d ", x); }
    printf("%d", f());
}

57 What is printed?

#include <stdio.h>
#include <stdlib.h>
int main() {
    printf("%d %d", abs(-7), (int)strtol("1010", NULL, 2));
}

58 Given char *s = "ABCD";, what does *(s + 2) - *s evaluate to?

59 What is the effect of defining int f(void) versus int f() in C?

60 What does g(1234) print?

void g(int n) {
    if (n == 0) return;
    g(n / 10);
    printf("%d", n % 10);
}