C Programming Pointers Quiz

What is a pointer in C?

• A variable that stores the address of another variable.

• A variable that stores data.

• A keyword in C.

• None of the above.

Answer explanation

A pointer in C is specifically defined as a variable that holds the address of another variable, allowing for direct memory access and manipulation. This makes the first choice the correct answer.

Which operator is used to get the value at the address stored in a pointer variable?

• &

• *

• %

• $

Answer explanation

The '*' operator is used to dereference a pointer, allowing you to access the value stored at the address contained in the pointer variable. Therefore, the correct answer is '*', not '&', '%', or '$'.

What is the output of the following code? int x = 10; int *p = &x; printf("%d", *p);

• 10

• Address of x

• Garbage value

• Compiler error

Answer explanation

The code initializes an integer x with 10 and a pointer p that points to x. The printf statement dereferences p, accessing the value of x, which is 10. Therefore, the output is 10.

Which of the following is the correct way to declare a pointer to an integer?

• int p;

• int *p;

• int &p;

• int ptr;

Answer explanation

The correct way to declare a pointer to an integer is 'int *p;'. This syntax indicates that 'p' is a pointer variable that can hold the address of an integer. The other options do not correctly declare a pointer.

What will be the output of the following code? int x = 5; int *p = &x; *p = 20; printf("%d", x);

• 5

• 20

• Address of x

• Compiler error

Answer explanation

The code initializes x to 5, then uses a pointer p to change the value of x to 20. The printf statement outputs the current value of x, which is now 20. Therefore, the correct answer is 20.

Which of the following statements is true about pointers?

• Pointers can be used to access array elements.

• Pointers cannot be used with functions.

• Pointers are not allowed in C.

• Pointers can only point to integer variables.

Answer explanation

The correct statement is that pointers can be used to access array elements. Pointers are versatile in C, allowing access to arrays, functions, and various data types, not just integers.

What is the output of the following code? int arr[] = {10, 20, 30}; int *p = arr; printf("%d", *(p + 1));

• 10

• 20

• 30

• Compiler error

Answer explanation

The pointer 'p' points to the first element of 'arr'. The expression '(p + 1)' accesses the second element of the array, which is '20'. Thus, the output of the code is '20'.

Which of the following is the correct syntax to declare a pointer to a pointer?

• int **p;

• int p;

• int p**;

• int ptr;

Answer explanation

The correct syntax to declare a pointer to a pointer in C is 'int **p;'. This means 'p' is a pointer that points to another pointer of type 'int'. The other options do not correctly represent a pointer to a pointer.

What will be the output of the following code? int x = 10; int *p = &x; int **q = &p; printf("%d", **q);

• 10

• Address of x

• Address of p

• Compiler error

Answer explanation

The code initializes an integer x with 10, a pointer p to x, and a pointer q to p. The expression **q dereferences q to get p, then dereferences p to get the value of x, which is 10. Thus, the output is 10.

Which of the following is true about pointer arithmetic?

• You can add two pointers.

• You can subtract one pointer from another.

• You can multiply two pointers.

• You can divide one pointer by another.

Answer explanation

You can subtract one pointer from another to determine the number of elements between them in an array. However, adding, multiplying, or dividing pointers is not valid in pointer arithmetic.