Discussion
If malloc() successfully allocates memory it returns the number of bytes it has allocated.
#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\n",*p);
return(0);
}
Answer: A
The program is not valid. Try replacing "int *p;" with "int *p = NULL;" and it will try to dereference a null pointer. This is because fun() makes a copy of the pointer, so when malloc() is called, it is setting the copied pointer to the memory location, not p. p is pointing to random memory before and after the call to fun(), and when you dereference it, it will crash. If you want to add memory to a pointer from a function, you need to pass the address of the pointer (ie. double pointer).
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