Pointer – HackerRank Solution

Pointer – HackerRank Solution

Problem :

pointer in C is a way to share a memory address among different contexts (primarily functions). They are primarily used whenever a function needs to modify the content of a variable, of which it doesn’t have ownership.

In order to access the memory address of a variable,val, we need to prepend it with & sign. E.g., &val returns the memory address of val.

This memory address is assigned to a pointer and can be shared among various functions. E.g. int* p = &val will assign the memory address of val to pointer p. To access the content of the memory to which the pointer points, prepend it with a *. For example, *p will return the value reflected by val and any modification to it will be reflected at the source (val).

void increment(int *v) {
    (*v)++;
}

int main() {
    int a;
    scanf("%d", &a);
    increment(&a);
    printf("%d", a);
    return 0;
}  

You have to complete the function void update(int *a,int *b), which reads two integers as argument, and sets a with the sum of them, and b with the absolute difference of them.

  • a' = a + b
  • b' = |a - b|

Input Format :

Input will contain two integers, a and b, separated by a newline.

Output Format :

You have to print the updated value of a and b, on two different lines.

P.S.: Input/output will be automatically handled. You only have to complete the void update(int *a,int *b) function.

Sample Input :

4
5

Sample Output :

9
1

Explanation :

  • a' = 4 + 5 = 9
  • b' = |4 - 5| = 1

Solution :

#include <stdio.h>

void update(int *a,int *b) {
       int x = 0;
        x = *a + *b;
        *b = *a - *b;
        *a = x;
        if (*b < 0)
            *b = *b / -1;
}

int main() {
    int a, b;
    int *pa = &a, *pb = &b;
    
    scanf("%d %d", &a, &b);
    update(pa, pb);
    printf("%d\n%d", a, b);

    return 0;
}

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