Pointers in C HackerRank Solution
Objective
In this challenge, you will learn to implement the basic functionalities of pointers in C. A 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 that it does not own.
In order to access the memory address of a variable, val, prepend it with & sign. For example, &val returns the memory address of val.
This memory address is assigned to a pointer and can be shared among various functions. For example, 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;
}
Task
Complete the function void update(int *a,int *b). It receives two integer pointers, int* a and int* b. Set the value of a to their sum, b and to their absolute difference. There is no return value, and no return statement is needed.
-
a’ = a+b
-
b’ = |a-b|
Input Format
The input will contain two integers, a and b, separated by a newline.
Output Format
Modify the two values in place and the code stub main() will print their values.
Note: Input/ouput will be automatically handled. You only have to complete the function described in the 'task' section.
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) {
// Complete this function
int sum,diff;
sum = *a+*b;
diff = abs(*a-*b);
*a = sum;
*b = diff;
}
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;
}
Steps Used in solving the problem -
-
First, we included the required header file.
-
Then, we defined a function that takes two integer pointers, a and b, as arguments. We also declared two integer variables, ‘sum’ and 'diff'. sum will store the sum of two integers, and diff will store the absolute difference.
-
Then we declared the main function. Inside our function, we declared two integer variables, a and b, and two integer pointers,
paandpb,that point toaandb. -
We used the scanf function to read the inputs and called the update function to update the values of a and b.
-
At last, we used the printf function to print the result.
