How many numbers higher than average [C++] - c++

Question

I filled an array with 30 random numbers and calculated average. I want to display how many numbers are higher than the average. I tried making a function "aboveAverage" and check if the numbers are higher than the average and than just increase the count "num_over_average++". The problem is I don't know how to pass a value "avg" from function to another function.
#include <iostream>
#include <ctime>
using namespace std;
const int n = 30;
void fillArray(int age[], int n) {
srand(time(NULL));
for (int index = 0; index < n; index++) {
age[index] = (rand() % 81) + 8;
}
}
void printArray(int age[], int n) {
for (int index = 0; index < n; index++) {
cout << age[index] << endl;
}
}
double printAverage(int age[], int n) {
double sum;
double avg = 0.0;
for (int i = 0; i < n; i++) {
sum = sum + age[i];
}
avg = ((double) sum) / n;
cout << avg << endl;
return avg;
}
void aboveAverage(int age[], int n) {
double avg;
int num_over_average = 0;
for(int i = 0; i < n; i++){
if(age[i] > avg) {
num_over_average++;
}
}
cout<<num_over_average;
}
int main(int argc, char *argv[]) {
int age[n];
fillArray(age, n);
cout << "array: " << endl;
printArray(age, n);
cout << endl;
aboveAverage(age, n);
//example: Days above average: 16
}

Answer 1

This should be a comment, but I don't have enough reps :(
Change aboveAverage to void aboveAverage(int age[], int n, double avg)
Return avg from printAverage function
Change the last part of your main code to
double avg;
avg = printAverage(age, n);
aboveAverage(age, n, avg);
Hope this helps!

Answer 2

You have two solutions using your code:
Either you call printAverage() to initialise avg in aboveAverage() :
void aboveAverage(int age[], int n) {
double avg = printAverage();
...
}
Or you pass the average at parameter of aboveAverage() after having computed it with printAverage() :
void aboveAverage(int age[], int n, double avg) {
...
}

Answer 3

If you use the standard library you can do that with two lines of code:
double average = std::accumulate(std::begin(age), std::end(age), 0.0) / std::size(age);
int above_average = std::count_if(std::begin(age), std::end(age),
[average](double value) { return average < value; });
Okay, you might count that as three lines.
One major advantage of this approach over the code in the question is that you can change the container type to, say, vector<double> without having to change any of this code.

Answer 4

Well is pretty simple but dependent on your situation, I'll elaborate.
I'm the case when it's part of a bigger function (do-somthing())
You could calculate the average value like so and pass it to your "aboveAverage" function and print it:
double n_average = printAverage(nArr_ages, n_agesArraySize);
aboveAverage(nArr_ages, n_agesArraySize, n_averag);
Myself would probably rewrite the printAverage function as two functions, one that returns the average value based on the array and another that prints it not both at once because it violates the SOLID principals of a single responsibility and that a function name should reflect exactly what it does, in this case maybe calculateAverage or getAverageAge or any other appropriate name will do (try and name your functions like the english language so your code will be read like a song.
For example:
const size_t n = 30;
double calculateAverage(int nArr_ages[], int n_agesArraySize) {
double sum = 0.0;
double avg = 0.0;
for (int indexInArray = 0; indexInArray < n_agesArraySize; indexInArray++) {
sum = sum + age[indexInArray];
}
average = ((double) sum) / n_agesArraySize;
return average;
}
int aboveAverageCells(int ages[], int n_agesArraySize ) {
double average = calculateAverage(ages, n);
int num_over_average = 0;
for(int indexInArray = 0; indexInArray < n_agesArraySize; indexInArray++) {
if(ages[indexInArray] > avg) {
num_over_average++;
}
}
return num_over_average;
}
Now just call them in order, save the returned values to local variables in the main function and print using cout also locally in main.
As a side note next time maybe choose different names for the const and the local functions variable for the array size.