ME test series

Question

Consider the following program segment

int main()
{
    char *str = "GATECS";
    printf("%d",madeeasy(str));
    return 0;
}
int madeeasy(int *p1)
{
    int *p2=p1;
    while(*++p1);
    return(p1-p2);
}

The output of the above program will be _____ . Assume that the object of data type $int$ occupies $2$ bytes.

Comments

This question is from MADEEASY test series.

---

This is a bad question because of reason explained by arjun sir in this comment

You should not use an integer pointer to point to a character array or else behaviour is undefined in C. This is because C language supports memory alignment for integers where any integer can be assumed to start from an address which is a multiple of sizeof int.

Answer 1

Ans 3

p2 will point to 0 th position i.e G in string array.

after while loop p1 will point to end of string i.e null \0 which is at position 6.

So, 6-0/2 = 3.

why divide by 2 because it is integer pointer and int is given of size 2 byte and char is of 1 byte so one int chunk can accommodate 2 bytes.

Comments

before this, u should know the how addresses are going to be incremented because u might have seen such questions like some pointer incrementation or some questions like what kind of pointer it is whether it is character pointer or float pointer or integer pointer so depending on the type or size of data type u have to increase the step size in array type questions..

---

@akash
here the code is
while(*++p1)
So, the starting address gets incremented
if the code is
while(++*p1)
then ascii character  of 'G' will be incremented
right?
(just asking)

---

yes because * and ++ (pre-increment) are both of same priority but a right to left associative.

Answer 2

3 will be printed.

b will point to 'G' and a will point to null string ( \0 )

For subtraction of two pointers, if p1 and p2 are both pointers of type T *, then the value computed is:

    ( p2 - p1 ) = ( addr( p2 ) - addr( p1 ) ) / sizeof( T )

In the context of your program, let base address of the string be 2000. So, b = 2000 and a = 2006 (as char will take 1 byte)

Now, a - b = $\frac{address(a) - address(b)}{size of integer}$  = $\frac{2006 - 2000}{2}$ = 3

Comments

1.How we can assign character pointer to integer,its giving error.

2.difference in pointer give no of elemets b/w them.Here they are 6.

---

• pointer passed is char pointer to int pointer receiving function, even if implicit conversion takes place and code run.
• you have taken char as 1 bytes(even though in question it is mentioned all data types are 2 bytes) and then suddenly divide by 2 as the size of an int. The division is done by SIZEOF(OBJECT).