C++ 将二维数组传递给函数

Question

了解要计算数组的平均值，我们需要在下面声明一个函数。逐行循环和读取。

double getAverage(int arr[], int size)
{
  int    i, sum = 0;       
  double avg;          

  for (i = 0; i < size; ++i){
    sum += arr[i];
   }

  avg = double(sum) / size;    
  return avg;
}

之后我们会调用main的值。

#include <iostream>
using namespace std;

// function declaration:
double getAverage(int arr[], int size);

int main ()
{
   // an int array with 5 elements.
   int balance[5] = {1000, 2, 3, 17, 50};
   double avg;

   // pass pointer to the array as an argument.
   avg = getAverage( balance, 5 ) ;

   // output the returned value 
   cout << "Average value is: " << avg << endl; 

   return 0;
}

所以我的问题是，如果我想计算行*列的平均值怎么办？我要宣布这样的事情吗？假设行和列的大小是 arr[3][6]

double getAverage(int arr[][6], int noOfrows, int noOfcol)
{
    float sum=0, average;

    for (int i = 0 ; i < noOfrows ; i++) {
        for (int j = 0; j<noOfcol; j++) {    
        sum = sum + arr[i][j];    
        }
    }
        average = (float)sum / (float)(noOfcol*noOfrows);
        cout << "   " << average;

        return average; 
}

这是我的代码

int main()
{   
    int sales[3][6] = {{1000, 800, 780, 450, 600, 1200},
                       {800, 900, 500, 760, 890, 1000},
                        {450, 560, 570, 890, 600, 1100}};

    int avg;

    int choice;//menu choice

    const int computeAverage_choice = 1,
              computeTotal_choice = 2,
              listMaxMin_choice = 3,
              Exit_choice = 4;

    do
    {   
            //displayMenu(); // Show Welcome screen
            choice = displayMenu();
            while (choice < 1 || choice > 4)
         {
               cout << "Please enter a valid menu choice: " ;
               cin >> choice;
         }

            //If user does not want to quit, proceed.
         if (choice != Exit_choice)
         {  

                    switch (choice)
                    {
                           case computeAverage_choice:
                                avg = computeAverage(sales, 3, 6);
                                cout<<"The averge:" << avg;

                                break;

                           case computeTotal_choice:
                                //reserves
                                break;

                           case listMaxMin_choice:
                                //reserves
                                break;
                    }
         }
         } while (choice != Exit_choice);
            return 0;
}

Answer 1

如果您的函数声明如下:double getAverage(int arr[][6], int noOfrows, int noOfcol) 但是您正在尝试调用它使用 avg = getAverage( balance, 5 ) ; [只有 2 个参数] 你的编译器应该返回一个错误。

只需将调用调整为 avg = getAverage( balance, 5 */num or rows*/, 6 */num of cols*/) ;

#include <iostream>
using namespace std;

 double getAverage(int arr[][6], int noOfrows, int noOfcol)
{
    float sum=0, average;

    for (int i = 0 ; i < noOfrows ; i++) {
        for (int j = 0; j<noOfcol; j++) {

        sum = sum + arr[i][j];

        }
    }
        average = (float)sum / (float)(noOfcol*noOfrows);
        cout << "   " << average;

        return average; 
}


 int main()
 {
    int a[2][6] = {{1,2,3,4,5,6},{2,3,4,5,6,7}};
    getAverage(a, 2, 6);   // OK
    getAverage( a, 5 ) ;   // compile error
    return 0;
 }