Quiz for Dynamic memory allocation malloc

Q1: Which header file is required for using malloc() in C?

A. <stdlib.h> B. <stdio.h> C. <string.h> D. <math.h>

Q2: What does malloc() return when it fails to allocate memory?

A. NULL pointer B. 0 C. Random address D. Garbage value

Q3: The malloc() function allocates memory from which area?

A. Heap B. Stack C. Code segment D. Register

Q4: What is the correct syntax to allocate memory for an array of 10 integers using malloc()?

A. int *p = malloc(10 * sizeof(int)); B. int p = malloc(10); C. int *p = malloc(sizeof(int)); D. int *p = malloc(10);

Q5: Which function is used to free memory allocated by malloc()?

A. free() B. delete() C. remove() D. clear()

Q6: What happens if you access memory after calling free()?

A. Undefined behavior B. Program will exit C. It will print zero D. Memory is reallocated automatically

Q7: What is the default value of memory allocated using malloc()?

A. Garbage value B. Zero C. Minus one D. NULL

Q8: How can you initialize memory allocated by malloc to zero?

A. Use calloc() B. Use init() C. Use memset() D. Use zeromem()

Q9: Which of the following is true about malloc()?

A. It returns void* B. It initializes memory to zero C. It allocates on stack D. It cannot fail

Q10: What should be done after using malloc allocated memory?

A. Call free() B. Nothing required C. Call malloc again D. Restart program

Q11: What is the time complexity of malloc() allocation?

A. O(1) B. O(n) C. O(log n) D. Depends on OS

Q12: Which type of pointer should store the return value of malloc()?

A. Same type as allocated memory B. Always void* C. char* only D. int* only

Q13: What happens if malloc() is used without freeing in a loop?

A. Memory leak B. Automatic garbage collection C. Error message D. Memory reuse

Q14: How can malloc() allocation size be changed?

A. Use realloc() B. Call malloc again C. Change pointer D. Use memset()

Q15: If malloc(0) is called, what happens?

A. Implementation-defined B. Always returns NULL C. Allocates 1 byte D. Crashes

Q16: Which of the following is the safest way to check malloc success?

A. if(ptr != NULL) B. if(ptr) C. if(!ptr) D. All of the above

Q17: Which function can help detect memory leaks in C?

A. Valgrind B. free() C. debug() D. trace()

Q18: What will happen if you free() the same pointer twice?

A. Undefined behavior B. Double freed memory will be reused C. OS will ignore D. It will crash always

Q19: What should be included to avoid casting malloc result in C?

A. <stdlib.h> B. <stdio.h> C. <memory.h> D. <malloc.h>

Q20: Which of the following is an alternative to malloc() for allocating memory?

A. calloc() B. printf() C. sizeof() D. free()