What is the purpose of typecasting in malloc()? int *p = (int*)malloc(sizeof(int));

The correct answer is C: It improves code readability and is good practice (optional in C, mandatory in C++). Typecasting malloc() is optional in C but improves readability. It's mandatory in C++.

In C, a string is internally represented as:

The correct answer is A: An array of characters terminated by '\0'. In C, strings are null-terminated character arrays. The null character '\0' marks the end of the string.

In a for loop with multiple break statements in different conditions, which break will be executed?

The correct answer is C: The break statement whose condition is true. Only the break statement whose associated if condition evaluates to true will be executed, exiting the loop immediately.

What is the return type of malloc()?

The correct answer is A: void*. malloc() returns a generic pointer (void*) which can be cast to any data type pointer.

What is the size of the following structure? struct point { int x; int y; float z; };

The correct answer is B: 12 bytes. int x = 4 bytes, int y = 4 bytes, float z = 4 bytes. Total = 12 bytes (no padding in this case on most systems).

Home

Home › Subjects › C Programming › Pointers

C Programming
Pointers

C language from basics to advanced placement prep

21 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 11–20 of 21

Topics in C Programming

All Basics & Syntax 86 Data Types & Variables 97 Control Flow 100 Functions 99 Arrays & Strings 100 Pointers 99 Structures & Unions 100 File Handling 100 Dynamic Memory 98 Preprocessor 99

Q.11 Hard Pointers

What is the primary use of const pointer (int * const p)?

A Prevent modification of the value pointed to

B Prevent modification of the pointer itself

C Prevent allocation of memory

D Prevent deallocation of memory

Correct Answer: B. Prevent modification of the pointer itself

EXPLANATION

int * const p is a constant pointer - the pointer address cannot be changed, but the value it points to can be modified.

Test

Q.12 Hard Pointers

What does realloc() do?

A Allocates new memory block

B Resizes an existing allocated memory block and returns new address

C Frees memory and allocates new

D Initializes memory to zero

Correct Answer: B. Resizes an existing allocated memory block and returns new address

EXPLANATION

realloc() changes the size of previously allocated memory. It may return the same address or a new one depending on availability.

Test

Q.13 Hard Pointers

What will be the output?
int arr[3][3] = {{1,2,3}, {4,5,6}, {7,8,9}};
int *p = (int *)arr;
printf("%d", *(p+5));

A 5

B 6

C 8

D Garbage value

Correct Answer: B. 6

EXPLANATION

Converting 2D array to int pointer treats it as 1D. p+5 points to the 6th element (0-indexed), which is 6.

Test

Q.14 Hard Pointers

What is the relationship between arrays and pointers in C?

A Arrays are pointers

B Pointers are arrays

C Array names decay to pointers to their first element in most contexts

D No relationship

Correct Answer: C. Array names decay to pointers to their first element in most contexts

EXPLANATION

In most contexts, array names automatically decay to pointers to their first element. This is why array[i] is equivalent to *(array+i).

Test

Q.15 Hard Pointers

A programmer uses a pointer variable but forgets to initialize it before dereferencing. Which type of error will occur?

A Compile-time error

B Syntax error

C Runtime error or undefined behavior

D Logical error

Correct Answer: C. Runtime error or undefined behavior

EXPLANATION

Uninitialized pointers contain garbage values. Dereferencing them accesses arbitrary memory locations, causing runtime errors or undefined behavior.

Test

Q.16 Hard Pointers

Consider: int *p = (int *)malloc(5 * sizeof(int)); for(int i=0; i

A delete p;

B free(p);

C free(&p);

D p = NULL;

Correct Answer: B. free(p);

EXPLANATION

malloc() allocated memory must be freed using free(p), not free(&p). After freeing, it's good practice to set p = NULL.

Test

Q.17 Hard Pointers

In a function that returns a pointer, which of the following is UNSAFE?

A Returning a pointer to dynamically allocated memory (malloc)

B Returning a pointer to a local variable

C Returning a pointer to a global variable

D Returning a pointer to a static variable

Correct Answer: B. Returning a pointer to a local variable

EXPLANATION

Returning a pointer to a local variable is unsafe because the variable ceases to exist after the function returns, creating a dangling pointer.

Test

Q.18 Hard Pointers

What is the output?
int x = 50;
int *p = &x;
int *q = p;
q = NULL;
printf("%d", *p);

A 50

B NULL

C Garbage value

D Segmentation fault

Correct Answer: A. 50

EXPLANATION

Setting q to NULL doesn't affect p. p still points to x, so *p is 50.

Test

Q.19 Hard Pointers

Which statement is true about void pointers?

A Cannot be dereferenced without casting

B Can only point to void type

C Are always NULL

D Cannot be incremented

Correct Answer: A. Cannot be dereferenced without casting

EXPLANATION

void pointers are generic pointers that must be cast to appropriate type before dereferencing.

Test

Q.20 Hard Pointers

What does the following code do?
int *p = (int*)malloc(sizeof(int));
*p = 5;
free(p);
p = NULL;

A Allocates, assigns, deallocates and nullifies pointer

B Creates a memory leak

C Causes segmentation fault

D Compilation error

Correct Answer: A. Allocates, assigns, deallocates and nullifies pointer

EXPLANATION

This is proper memory management: allocate, use, free, and nullify to prevent dangling pointer.

Test

1 2 3

All Subjects & Topics

Govt. Exams

Entrance Exams

Teacher Exams

Subjects

Quick Links

C Programming Pointers

C Programming
Pointers