Function not returning any value in following code

Question

#include <bits/stdc++.h>

using namespace std;

int myfunc(int n, int m, int k, int arr[], int arr1[]) {

    int x = 0, y = 0;
    for (int i = 0; i < n; ++i) {
        if (arr[i] > k) {
            x += 1;
        }
    }

    for (int i = 0; i < m; ++i) {

        if (arr1[i] > k) {
            y += 1;
        }
    }

    return max(x, y); // why is this not working?

}
int main() {

    int n, m, k;

    int arr[n];

    int arr1[m];

    cin >> n >> m >> k;

    cout << "first: \n";

    for (int i = 0; i < n; ++i) {

        cin >> arr[i];
    }
    cout << "2nd arr\n";
    for (int i = 0; i < m; ++i) {
        cin >> arr1[i];
    }
    myfunc(n, m, k, arr, arr1);

    return 0;
}

In this code function is not returning any value but when I use cout<<max(x,y) instead of return max(x,y), it's working fine. Can anyone explain me why is this happening?

How do you know it's not returning anything? You're not doing anything with the return value. — Guy Incognito, Jan 03 '21 at 20:00
your code doesn't compile: https://godbolt.org/z/o94sbb. unrelated but see https://stackoverflow.com/questions/31816095/why-should-i-not-include-bits-stdc-h — Alan Birtles, Jan 03 '21 at 20:01
_"In this code function is not returning any value but when I use cout< — Lukas-T, Jan 03 '21 at 20:04
Welcome to Stack Overflow! [You should never use #include ](https://stackoverflow.com/questions/31816095/why-should-i-not-include-bits-stdc-h). — rsjaffe, Jan 03 '21 at 20:45

score 0 · Accepted Answer · answered Jan 03 '21 at 20:16

Your confusion seems to be arising from a misunderstanding of what it means to return a value from a function versus printing the value inside the function. Consider the following function that prints the right answer:

void f() 
{
  std::cout << 42;
}

Fine, this works and can be called like f();, and it prints the values.

On the other hand, if the function were to return a value, like this:

int f()
{
  return 42;
}

then simply calling the function f(); is not going to do anything because you are not using the returned value. Instead, you need to do something like:

std::cout << f();

From C++17, you can use an attribute for a function that returns a value, indicating that the returned value is meant to be used, and that not using it is a mistake:

[[nodiscard]] int f()
{
  return 42;
}

This has the nice property that a call like f(); will throw a warning, and the only way to avoid the warning is to actually use the returned value.

Function not returning any value in following code

1 Answers1