Max and Min is coming out as true instead of a number, what do I do?

Question

I need the minimum and maximum number out of an array but it is telling me that the address of function will always come out to true instead of a number. I can't figure out what to change.

#include <iostream>

using namespace std;

int main()
{
    double num1[10] {0.61, 1.70, 0.52, 1.34, 0.25, 1.20, 0.46, 1.10, 1.68, 1.37}; //material used in february
    double total1 {0};
    float average1 {0};
    int i;

    for (i=0; i<10; i++)
    {
        total1 = total1 + num1[i];
    }

    average1 = total1/10.0; //average of material used in feb

    double max1(double num1); // maximum of material used in feb

    double min1(double num1); // minimum of material used in feb

    cout << "Maximum is " << max1 << endl;
    cout << "Average is " << average1 << endl;
    cout << "Minimum is " << min1 << endl;


    double num2[10] {1.64, 1.15, 1.34, 1.63, 0.93, 0.51, 1.13, 1.16, 1.56, 1.38}; //material used in march
    double total2 {0};
    float average2 {0};
    int l;

    for (l=0; l<10; l++)
    {
        total2 = total2 + num2[l];
    }

    average2 = total2/10.0; //average of material used in march
    
    double max2(double num1); // maximum of material used in march

    double min2(double num1); // minimum of material used in march 

    cout << "Maximum is " << max2 << endl;
    cout << "Average is " << average2 << endl;
    cout << "Minimum is " << min2 << endl;

    return 0;

}

Answer 1

You are not printing a maximum here, you are printing a function pointer which is implicitly converted to bool. It is never nullptr, so it is true.

// These two lines are actually forward-declarations of two functions
// called max1 and min1.
double max1(double num1);
double min1(double num1);

cout << "Maximum is " << max1 << endl; // printing function pointer here
cout << "Average is " << average1 << endl;
cout << "Minimum is " << min1 << endl; // printing function pointer here

What you need instead is this:

#include <algorithm>
#include <numeric>
#include <array>

int main()
{
    constexpr std::array<double, 10> num1 {
        0.61, 1.70, 0.52, 1.34, 0.25, 1.20, 0.46, 1.10, 1.68, 1.37
    };

    double *max1 = std::max_element(std::begin(num1), std::end(num1));
    double *min1 = std::min_element(std::begin(num1), std::end(num1));
    double avg1 = std::accumulate(std::begin(num1), std::end(num1), 0.0)
                  / num1.size();

    // Note that we only need std::endl if we want to flush std::cout.
    // Otherwise '\n' is enough.
    std::cout << "Maximum is " << *max1 << '\n';
    std::cout << "Minimum is " << *min1 << '\n';
    std::cout << "Average is " << avg1 << '\n';

    // ...
}

std::min_element returns a pointer to the minimum in a range (in your case an array).

std::begin and std::end return iterators to the beginning and end of your array. This works with both std::array and C-style arrays.

Also note that std::accumulate can be used to compute the sum with ease. You don't need to write a loop for that yourself.

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Also see Iterator = pointer? Or what is it? for more information on iterators and pointers and what the difference is.