Array as an argument of a function in C++

Asked Apr 14 '20 at 16:43

Active Apr 14 '20 at 16:46

Viewed 27 times

This is a question on C++. I tried defining a function that computes the average of all elements in an array of doubles as follows, through the sizeof function that enables us to compute the length of the array.

#include<iostream>
#include<cstddef>

using namespace std;

double getAverage(double arr[]) {
  double sum =0;       
  double avg;          
  size_t size = sizeof(arr)/sizeof(*arr);  \\ to calculate the length of the array arr

   for (size_t i = 0; i < size; ++i) {
      sum += arr[i];
   }
   avg = sum / size;

   return avg;
}

int main () {
   double balance[] = {1000, 2, 3, 17, 50};
   double avg = getAverage(balance) ;
   cout << "Average value is: " << avg << endl; 
   return 0;
}

However, instead of 214.4, it returns 1000, which is clearly wrong. Is it legitimate to pass an array as an argument of a function in C++?

asked Apr 14 '20 at 16:43

Richard

Array parameters decay to pointers. `arr` has type `double*`. `sizeof(arr) = sizeof(double*) = sizeof(void*)`. – Evg Apr 14 '20 at 16:46
1

tl;dr of the dupe: `balance` is an array, but `arr` is a pointer. Use `std::vector` or `std::array` to avoid such trouble – 463035818_is_not_an_ai Apr 14 '20 at 16:47

Array as an argument of a function in C++

0 Answers0