Question

Consider the following C code:
#include <stdio.h>
int *assignval(int *x, int val)
{ *x = val;
return x;
}
void main( )
{ int* x = malloc (size of (int));
if (NULL = = x) return;
x = assignval(x, 0);
if(x)
{ x = (int*) malloc (size of (int));
if (NULL = = x) return;
x = assignval (x, 10);
}
printf ("%d"\n", *x);
free (x);
}
The code suffers from which one of the following problems:

• A. compiles successfully but execution may result in dangling pointer
• B. compiler error because the comparison should be made as x == NULL and not as shown
• C. compiles scornfully but execution may result in memory leak
• D. compiler error as the return of malloc is not typecast appropriately

Answer 1

The correct option is C compiles scornfully but execution may result in memory leak

In main( ) function, malloc( ) function return a void type address. So no need of type casting i.e., (int*) malloc (size of (int));, inplace of type casting malloc (size of (int)); will not give compilation error. Assignval( ) function assign
0 in memory location pointed by ‘x’ and return address of memory location pointed by ‘x’. Since next malloc( ) function can take memory location assign by previous malloc( ) function
because there is no free(m) is given to freed previously assign memory location.
So this can give memory leak problem if variable 'x' non-zero value.