c++ - (C++) 试图完成一个快速程序，但我不确定哪里出错了？

Question

程序说明如下。当我尝试编译时，出现错误提示 'cannot convert 'double' to 'double**' for argument。

Write a program that dynamically allocates an array large enough to hold a user-defined number of test scores. Once all the scores are entered, the array should be passed to a function that sorts them in ascending order. Another function should be called that calculates the average score. The program should display the sorted list of scores and averages with appropriate headings.

注意:我对在 C++ 中使用指针还很陌生，我确实意识到我的代码中的错误对于某些人来说可能相当容易发现，所以请放轻松。此外，如果对我可以改进的地方或在哪里可以找到对指针的其他引用有任何建议，那就太好了!

#include <iostream>
#include <iomanip>

using namespace std; 

//Function Prototypes
void arrSelectionSort( double *[], int );
double testAverage( double *[], int );

int main() { 

    double *testScores; //To dynamically allocate an array

    int numTest;    //To hold the number of test - size of array
    int count;      //Counter variable


    //User input
    cout <<"Please enter the number of test scores: ";
    cin >> numTest; 

    //Dynamically allocate an array for test scores 
    testScores = new double[numTest];

    //Obtain the individual test scores from user
    cout << "\nEnter each test score.\n";
    for ( count = 0; count < numTest; count++ ) { 

        cout << "Test " << ( count + 1 ) << ": " << endl; 
        cin >> testScores[count];

    }

    //Function call to sorting algorithm 
    arrSelectionSort( testScores, numTest );


    //Display sorted array
    cout << "Here are the sorted test scores.\n";
    for ( int x = 0; x < numTest; x++ ) { 

        cout << "\nTest " << (x+1) << ": " << testScores[x];

    } 


    //Display average of all test scores
    cout <<"\nAverage of all test scores is: " << testAverage( testScores, numTest );


    //Free up allocated memory
    delete  [] testScores;
    testScores = 0; 

    return 0;
}

void arrSelectionSort( double *arr[], int size ) { 

    int startScan, minIndex; 
    double *minElement; 

    for ( startScan = 0; startScan < ( size - 1 ); startScan++ ) { 

        minIndex = startScan; 
        minElement = arr[startScan]; 

        for ( int index = startScan + 1; index < size; index ++ ) { 

            if (*(arr[index]) < *minElement) {

                minElement = arr[index]; 
                minIndex = index;  
            }

        }

        arr[minIndex] = arr[startScan]; 
        arr[startScan] = minElement; 
    }
}

double testAverage( double *arr[], int size ) { 

    double average;
    double total; 

    //Accumulating Loop
    for ( int count = 0; count < size; count++ ) { 

        total += arr[count];
    }

    average = total/size; 

    return average; 
}

Answer 1

从函数参数中删除 *:

void arrSelectionSort( double arr[], int size );
double testAverage( double arr[], int size );

您想传入一个 double 值数组，而不是一个 double* 指针数组。

然后，在 arrSelectionSort() 中，去掉 * 的使用，因为你想对值进行排序，而不是对指针进行排序:

void arrSelectionSort( double arr[], int size ) { 

    int startScan, minIndex; 
    double minElement; 

    for ( startScan = 0; startScan < ( size - 1 ); startScan++ ) { 

        minIndex = startScan; 
        minElement = arr[startScan]; 

        for ( int index = startScan + 1; index < size; index ++ ) { 

            if (arr[index] < minElement) {

                minElement = arr[index]; 
                minIndex = index;  
            }

        }

        arr[minIndex] = arr[startScan]; 
        arr[startScan] = minElement; 
    }
}