array to function

[gjur99]

hello fellow tech people!

Im having some trouble with passing an array to a function to do some operation(s).
My code runs and does what is asked to do. But, the little detail is that I need to
get the average through a function. I've done thorough reseach, but i still seem to
grasp the essence of it.

How can I do it so that when I run my code, and input all the 12 values. That thse are passed into a function that would basically all the 12 values and divide by 12. help?

 #include <iostream>
#include <iomanip>
using namespace std;

double yearlyRainAverage();

int main() {

    const int months = 12;
    double inchesofrain[months];
    double yearlyAverage;
    double sum = 0

    for (int count = 0; count < months; count++)
    {
        cout<<"Enter the rainfall (in inches) for month #"<< count + 1<<":  ";
        cin>>inchesofrain[count];

        sum += inchesofrain[count];


        if(inchesofrain[count] < 0){

            cout <<"Rainfall must be 0 or more.\n";
            cout<<"please re-enter: "<<endl;
            cout<<"Enter the rainfall (in inches) for month #"<< count + 1<<":  ";
            cin>>inchesofrain[count];

        }

    }
    cout << fixed << showpoint << setprecision(2) << endl;

    yearlyAverage = sum / 12;
    cout<<"the average is "<<yearlyAverage;


    return 0;
}

double yearlyRainAverage(){
    
}

[grizzlei]

I suggest you to use vectors.

#include <vector>
using namespace std;
static vector<float>yourArray(2);

float yourFunction(vector<float>Array){
Array[0] = 2.3f;
Array[1] = 2.2f;
}

then you can insert your array like this:

int main(int argc, char **argv){
yourFunction(yourArray);
return 0;
}

[nuderobmonkey]

double yearlyRainAverage( double  inchesOfRain[], const int months)
{
     double sum = 0;
     for (int i = 0;  i < months;  ++i) sum += inchesOfRain[i];
     return sum / months;
}

Consider that at passing arrays to functions these arrays will be passed as pointers. So the functions don't know their size.

I also agree with peytuk: It would be a benefit if you read up into std::vector facilities, that's the most often used container and has some useful advantages than builtin arrays.

[keskiverto]

Since a function receives a pointer that points to caller's array, the function can modify values in the array.

Calculation of average does not need to modify the array. The function can state that clearly:
double yearlyRainAverage( const double inchesOfRain[], const int months )
Now users of the function see that the function will not modify the array
and the compiler reports an error, if you try to modify inside the function.

[gjur99]

thank you all for your help!! is very much well appriciated! may I have one last question before I stop bothering you guys...

how can I find the subscript of the month and display it?
what is it that is not working in my function?

should say for example: "The largest amount of rainfall was: 2.00 inches in month 9"

#include <iostream>
#include <iomanip>
using namespace std;

double yearlyRainAverage(double[], const int);
double smallestRainfall(double [], const int);
double largestRainfall(double [], const int);
int searchHighestMonth(double[], const int, int);

int main() {

    const int months = 12;
    double inchesOfRain[months];
    double sumOfAllMonths=0;
    int monthPosition;

    monthPosition=searchHighestMonth(inchesOfRain, months, 12);


    for (int count = 0; count < months; count++)
    {
        cout<<"Enter the rainfall (in inches) for month #"<< count + 1<<":  ";
        cin>>inchesOfRain[count];

        sumOfAllMonths += inchesOfRain[count];


        if(inchesOfRain[count] < 0){

            cout <<"Rainfall must be 0 or more.\n";
            cout<<"please re-enter: "<<endl;
            cout<<"Enter the rainfall (in inches) for month #"<< count + 1<<":  ";
            cin>>inchesOfRain[count];

        }

    }
    cout << fixed << showpoint << setprecision(2) << endl;

    cout<<"the total rainfall for the year is "<<sumOfAllMonths<<" inches"<<endl;
    cout<<"the average is "<<yearlyRainAverage(inchesOfRain, 12)<<" inches"<<endl;

//    cout<<"The smallest amount of rainfall was: "<<smallestRainfall(inchesOfRain, 12)<<" inches ";
//    cout<<"in month "<<endl;

    cout<<"The largest amount of rainfall was: "<<largestRainfall(inchesOfRain, 12)<<" inches ";
    cout<<"in month "<<(monthPosition+1)<<endl;

    return 0;
}

double yearlyRainAverage(double inchesofrain[], const int months){
    double sum=0;
    for(int i=0;i<months; i++){
        sum+=inchesofrain[i];
    }
    return sum/months;
}

double smallestRainfall(double inchesofrain[], const int months){
    double smallest;
    int i;

    smallest=inchesofrain[0];
    for(i=0; i < months; i++){
        if(inchesofrain[i] < smallest){
            smallest = inchesofrain[i];
        }
    }
    return smallest;

}


double largestRainfall(double inchesofrain[], const int months){
    double largest;
    int i;

    largest=inchesofrain[0];
    for(i=0; i < months; i++){
        if(inchesofrain[i] > largest){
            largest = inchesofrain[i];
        }
    }
    return largest;
}

int searchHighestMonth(double inchesofrain[], const int months, int value){
    int index=0;
    int position = -1;
    bool found = false;

    while(index < months && !found){
        if(inchesofrain[index] == value)
        {
            found = true;
            position = index;
        }
        index++;
    }
    return position;
}


}

[keskiverto]

Consider:

int max_element( const double data[], int N )
{
  int max = 0;
  for ( int i=1; i < N; ++i) {
    if ( data[max] < data[i] ) {
      max = i;
    }
  }
  return max;
}

Then you can:

int maxmonth = max_element( inchesOfRain, months );
double maxrain = inchesOfRain[maxmonth];
std::cout << "Month " << maxmonth+1 << " had " << maxrain << " of rain\n";

[nuderobmonkey]

At line 17 you're trying to get the month from the values of your array, which is at that time not yet initialized ;)

[gjur99]

@keskiverto I tried what you told me, and yes. the result is now different but it gives me an incredibly long number (1x10^270)

[keskiverto]

Do the months have realistic rain values before you call the max_element?