. Document the function mystery. The documentation should explain what each line

Question

. Document the function mystery. The documentation should explain what each line
does and also give a general overview of what mystery does, that is, how mystery
computes the return value from the two arguments.

#include <stdio.h>

int mystery(int n1, int n2) {
unsigned char* ptr1 = (unsigned char*) &n1;
unsigned char* ptr2 = (unsigned char*) &n2;

int ret_val;
unsigned char* ptr3 = (unsigned char*) &ret_val;

ptr2 += sizeof(int) - 1;
ptr3 += sizeof(int) - 1;

int i;
for (i = 0; i < sizeof(int); i++) {
*ptr3 = *ptr2;
ptr3--;
ptr2--;
}

ptr3++;
*ptr3 = *ptr1;

return ret_val;
}

Explanation / Answer

// no mystery in this..

// you are just returning first parameter

int mystery(int n1, int n2) {
unsigned char* ptr1 = (unsigned char*) &n1;

// get address of n1 ptr1 points n1

unsigned char* ptr2 = (unsigned char*) &n2;

// get address of n2   ptr2 points n2

int ret_val;
unsigned char* ptr3 = (unsigned char*) &ret_val;

// get address of n1

ptr2 += sizeof(int) - 1;
ptr3 += sizeof(int) - 1;

int i;
// here some operation is going it doesnot matter what it is because

for (i = 0; i < sizeof(int); i++) {
*ptr3 = *ptr2;
ptr3--;
ptr2--;
}

ptr3++;
*ptr3 = *ptr1;
// here u are assiginig value of ptr3 to ptr1 which is n1
// again ptr3 points to ret_val
// thus ret_val = n1

// same as return n1
return ret_val;
}

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