Go4Expert - Pointer to point to 3rd byte of an integer

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Pointer to point to 3rd byte of an integer

One of the tricky question in interview comes out is

How do you point to the third byte of an integer. Assumption that integer is 4 byte. Here is the code to do the same

Code: CPP

#include <iostream>
using namespace std;

int main(int argc, char *argv[])
{
    int i = 35;              //integer variable
    int *ip = &i;            //Integer pointer
    void *vp = (int*)ip;     //Void pointer for type casting
    char *cp = (char*)vp;    //Char pointer
    cp++;                    //Point to second byte
    cp++;                    //Point to third byte
    return 0;
}

The concept is to have a void pointer to cast the integer pointer to the character pointer and increment that to point to the any byte location you wish to by simply incrementing it. Assumption char pointer is 1 byte.

Re: Pointer to point to 3rd byte of an integer

union {
int i;
char c[4];
} vars;

vars.c[2] is the third byte of vars.i.

Re: Pointer to point to 3rd byte of an integer

Quote:

Originally Posted by AhmedHan

union {
int i;
char c[4];
} vars;

vars.c[2] is the third byte of vars.i.

Yup thats also a nice way.

Re: Pointer to point to 3rd byte of an integer