尝试通过函数查找数组的最大值和最小值，其中数组值由用户输入

Question

I'm trying to create a program where the user is asked for 10 numbers, the numbers are all stored in an array list, and then the array list is put through a function, the function is going to return the max and min values.

So far I only have code for a max value but I can't get the function to work at all, I've been using this link to learn about passing arrays to functions:

http://www.tutorialspoint.com/cplusplus/cpp_passing_arrays_to_functions.htm

And I think I'm following their syntax correctly but I'm getting errors about the array not being declared in the function parameter, and how my function (minmax) simply cannot be used as a function and I'm beyond confused right now!

Apologies if the answer is obvious, I'm still new to C++

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


int minmax(array[]);

int main()
{

int numbers[10];
int input;

cout << "Please enter ten numbers" << endl;

for(int i=0;i<10;i++){

    cin >> input;
    numbers[i] = input;

    mm = minmax(numbers);

}

}

void minmax(array[]){


int max = 0;
for (int i = 0 ; i < size ; i++);
{
    if (list[i] > highNum)
        max = array[i];
        cout << array[i];
}
cout << max;

}

Answer 1

Assuming this is not a homework assignment (which would probably require you to actually roll your own "Min/max" function), this code would suffice:

std::vector<int> values(10);
cout << "Please enter ten numbers" << endl;

for(int i=0;i<10;i++){
    cin >> values[i];
}

int min_value = *std::min_element(values.begin(), values.end());
int max_value = *std::max_element(values.begin(), values.end());

Or if you need min/max values to be calculated with a single function invocation, you can rewrite those last two lines like this:

auto minmax = std::minmax_element(values.begin(), values.end());
int min_value = *(minmax.first);
int max_value = *(minmax.second);

Answer 2

#include<iostream>

using namespace std;


int minmax(int* array, int size);

int main()
{
    int numbers[10];
    int input, mm;

    cout << "Please enter ten numbers" << endl;

    for(int i=0;i<10;i++){
        cin >> input;
        numbers[i] = input;
    }

    mm = minmax(numbers, 10);

}

int minmax(int array, int size){
    int max = 0;

    for (int i = 0 ; i < size ; i++);
    {
        if (array[i] > max) {
            max = array[i];
            cout << array[i];
        }
    }
    return max;
}

Should work, but you should (re)read the C/C++ basics.

Another solution is to use <vector> and <algorithm> from std C++ lib.

Answer 3

Assuming this is not a homework assignment, here are some suggestions for your approach. (otherwise, @Xirema's answer is better approach)
3 things to start:
1) mm is not defined in your main.
2) the statement: mm = minmax(numbers); should be moved out of the for loop.
3) Also, this statement: mm = minmax(numbers); Suggests you need to change the function prototype of minmax in a couple of ways. See below.

Replace your minmax function (see comments in code for explanation)

int minmax(int array[], int size)//need types for arguments 
                                 //(int) and prototype needs 
                                 //to return a value (void -> int)
{

    int max = INT_MIN;//<limits.h> initialize to negative
                      // (-2147483647 - 1) for 32 bits
    for (int i = 0 ; i < size ; i++)
    {
        if (array[i] > max)
        {                    //added braces to be explict
             max = array[i]; // `list` should be `array`
                             //highNum is not needed, use max.
             cout << array[i];//Note, without curly braces, this 
                             //statement would not be executed
        }
    }
    cout << max;
    return max;  //requires a return value
}

Note, This preserves the result of what your original code example would have returned, maximum only.

Answer 4

You need to correct some mistakes:

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


int minmax(/*no type specified, should be int*/array[]);

int main()
{

    int numbers[10];
    int input;
    /*mm is not declared, but is used later, declare it*/

    cout << "Please enter ten numbers" << endl;

    for(int i=0;i<10;i++){

        cin >> input;
        numbers[i] = input;
        /*if minmax is void, then it cannot be assineg*/
        mm = minmax(numbers);

    }

}

/*minmax returns int in declaration, here returns void*/ void minmax(/*no type specified*/array[]){


    int max = 0;
    for (int i = 0 ; i < /*size was not declared, declare it*/ size ; i++);
    {
        if (/*list is undeclared, (did you mean array?)*/list[i] > /*highNum not declared, did you mean max?*/highNum)
            max = array[i];
        cout << array[i];
    }
    cout << max;

}