What is the problem with following code? C #include<stdio.h> int main() { int *p = (int *)malloc(sizeof(int)); p = NULL; free(p); }

Compiler Error: free can 't be applied on NULL pointer

The program may crash as free() is called for NULL pointer.

Consider the following program, where are i, j and k are stored in memory? C int i; int main() { int j; int *k = (int *) malloc (sizeof(int)); }

i is stored in BSS part of data segment, j is stored in stack segment. *k is stored on heap.

i, j and *k are stored in stack segment

i and j are stored in stack segment. *k is stored on heap.

j is stored in BSS part of data segment, i is stored in stack segment. *k is stored on heap.

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C Dynamic Memory Allocation

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Question 1

The most appropriate matching for the following pairs (GATE CS 2000)

X: m=malloc(5); m= NULL;        1: using dangling pointers
Y: free(n); n->value=5;         2: using uninitialized pointers
Z: char *p; *p = ’a’;           3. lost memory is:

X—1 Y—3 Z-2
(X—2 Y—1 Z-3
X—3 Y—2 Z-1
X—3 Y—1 Z-2

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Question 2

Consider the following three C functions :

[PI] int * g (void) 
{ 
  int x= 10; 
  return (&x); 
}  
  
[P2] int * g (void) 
{ 
  int * px; 
  *px= 10; 
  return px; 
} 
  
[P3] int *g (void) 
{ 
  int *px; 
  px = (int *) malloc (sizeof(int)); 
  *px= 10; 
  return px; 
}

Which of the above three functions are likely to cause problems with pointers? (GATE 2001)

Only P3
Only P1 and P3
Only P1 and P2
P1, P2 and P3

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Question 3

Output?

# include<stdio.h>
# include<stdlib.h>
 
void fun(int *a)
{
    a = (int*)malloc(sizeof(int));
}
 
int main()
{
    int *p;
    fun(p);
    *p = 6;
    printf("%d",*p);
    return(0);
}

May not work
Works and prints 6

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Question 4

Which of the following is/are true

calloc() allocates the memory and also initializes the allocates memory to zero, while memory allocated using malloc() has random data.
calloc() takes two arguments, but malloc takes only 1 argument.
Both malloc() and calloc() return \'void *\' pointer.
All of the above

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Question 5

What is the return type of malloc() or calloc()

void *
Pointer of allocated memory type
void **
int *

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Question 6

Which of the following is true?

"ptr = calloc(m, n)" is equivalent to following
ptr = malloc(m * n);
"ptr = calloc(m, n)" is equivalent to following
ptr = malloc(m * n); memset(ptr, 0, m * n);
"ptr = calloc(m, n)" is equivalent to following
ptr = malloc(m); memset(ptr, 0, m);
"ptr = calloc(m, n)" is equivalent to following
ptr = malloc(n); memset(ptr, 0, n);

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Question 7

What is the problem with following code?

#include<stdio.h>
int main()
{
    int *p = (int *)malloc(sizeof(int));

    p = NULL;

    free(p);
}

Compiler Error: free can\'t be applied on NULL pointer
Memory Leak
Dangling Pointer
The program may crash as free() is called for NULL pointer.

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Question 8

Consider the following program, where are i, j and k are stored in memory?

int i;
int main()
{
    int j;
    int *k = (int *) malloc (sizeof(int));
}

i, j and *k are stored in stack segment
i and j are stored in stack segment. *k is stored on heap.
i is stored in BSS part of data segment, j is stored in stack segment. *k is stored on heap.
j is stored in BSS part of data segment, i is stored in stack segment. *k is stored on heap.

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Question 9

Which languages necessarily need heap allocation in the run time environment?

Those that support recursion
Those that use dynamic scoping
Those that use global variables
Those that allow dynamic data structures

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Question 10

We use malloc and calloc for

Dynamic memory allocation
Static memory allocation
Both dynamic and static memory allocation
None of the above

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