無效類型的下標錯誤

Question

我在標記的「中值」函數中遇到了一些麻煩。我收到一個錯誤，說數組下標爲`Horse [10] [double]'。我不知道如何解決這個問題，我正在尋找一些友好的幫助。

#include <cstdlib> 
#include <iostream> 
#include <math.h> 

/* 
Name: Horses2 
Author: Grant Birkinbine 
Date: 03/12/14 18:25 
Description: A program that modifies the Horses program 
*/ 

//Start 

using namespace std; 

//Class 

class Horse{ 
    private: 
      string name ; 
      int lane; 
      double time; 

    public: 

      Horse(string hname , int hlane , double htime){ 
         name = hname ; 
         lane = hlane ; 
         time = htime; 
         } 
      Horse(){ 
        name = "" ; 
        lane = 0 ; 
        time = 0 ; 
        } 

      void setname(string hname){ 
       name = hname; 
       } 
      void setlane(int hlane){ 
       lane = hlane; 
       } 
      void settime(double htime){ 
       time = htime; 
       } 

      string getname(){ 
       return name ; 
       } 
      int getlane(){ 
       return lane; 
       } 
      double gettime(){ 
       return time; 
       } 

      void print(){ 
       cout << "Horse Name: " << name << endl; 
       cout << "Horse Lane: " << lane << endl; 
       cout << "Horse Time: " << time << endl; 
       cout << endl; 
       }  
}; 

//Main 

void insertion_sort(Horse x[],int length); 

int main(int argc, char *argv[]) 
{ 
cout << "Horse Race Results: " << endl << endl; 
Horse ahorse[10]; 

ahorse[0] = Horse("American idol " , 1 , 45.41); 
ahorse[1] = Horse("Bababooey " , 2 , 42.42); 
ahorse[2] = Horse("Charlie Horse " , 3 , 40.94); 
ahorse[3] = Horse("Dog Biscuit " , 4 , 43.55); 
ahorse[4] = Horse("Echo " , 5 , 41.41); 
ahorse[5] = Horse("Firefox " , 6 , 42.58); 
ahorse[6] = Horse("Google " , 7 , 42.58); 
ahorse[7] = Horse("Hoof-Hearted " , 8 , 44.57); 
ahorse[8] = Horse("Ima Loozer " , 9 , 41.57); 
ahorse[9] = Horse("Just Walking " , 10 , 50.00); 

//Sorting 

int length = 10; 
insertion_sort(ahorse, length); 

double avg; 
double x; 
double max; 
double min; 
avg=0; 
x = 0; 
int abovea = 4 ; 
int belowa = 6 ; 
int abovem = 4 ; 
int belowm = 4 ; 

     //Average 

     for (int i =0 ; i<10 ; i++) { 
     x = x + ahorse[i].gettime() ; 
     } 

     avg = (x/10); 

     //Max 

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

       max = -1000; 
       if (ahorse[i].gettime() > max){ 
       max = ahorse[i].gettime(); 
       } 
       } 

    //Min 

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

       min = 1000; 
       if (ahorse[i].gettime() < min){ 
       min = ahorse[1].gettime() ; 
          } 
          } 

     for(int i = 0; i < 10; i++){ 
       ahorse[i].print() ; 
       } 

     //Median 

     double median; 
     if(ahorse[x].gettime() % 2 == 0){ 
     median = (ahorse[10].gettime()/2) + (ahorse[10].gettime()/2 + 1)/2; 
     } 
     else{ 
     median = (ahorse[10].gettime()/2) + 1; 
     } 



     cout << "Average: " << avg << endl; 
     cout << "Fastest Time: " << min << endl; 
     cout << "Slowest Time: " << max << endl; 
     cout << "# Above Mean: " << abovea << endl; 
     cout << "# Below mean: " << belowa << endl; 
     cout << "# Above median: " << abovem << endl; 
     cout << "# Below median: " << belowm << endl; 
     cout << endl; 

system("PAUSE"); 
return EXIT_SUCCESS; 
} 

void insertion_sort(Horse x[],int length){ 

Horse key; 
int i; 
for(int j=1;j<length;j++) 
{ 
key= x[j]; 
i=j-1; 
while(x[i].gettime()>key.gettime() && i>=0) 
{ 
      x[i+1]=x[i]; 
    i--; 
} 
x[i+1]=key; 
} 
} 

Answer 1

首先，你不能使用雙到標的數組，所以ahorse[x].gettime()將無法​​正常工作，陣列必須使用整數下標。想一想，ahorse[9.5]指的是什麼元素？

其次，模數運算符%僅適用於整數。使用fmod如果你想要做雙

三模，數組索引從零開始，所以獲得ahorse[10]在中間部分被訪問數組外它的約束，是作爲最後一個元素無效的內存訪問Horse ahorse[10]陣列是ahorse[9]。

可能還有其他問題，但上面提到的問題是我第一眼看到的問題。