棒球擊球平均項目

Question

我需要一個幫助學校的項目。我們必須編寫一個程序，向用戶詢問關於棒球運動員的信息。我們需要計算玩家的擊球平均數，擊球次數和命中次數。我遇到了一個問題，即我的平均計算結果是輸出一個集合數並且沒有執行任何計算。我輸入用於計算的所有變量的整數。所以我會輸入數字如1，4，10等......由於該程序的價值，我的公式設置自己等於15903.876。我用於平均公式的所有變量均被聲明爲整數，而擊球平均本身被聲明爲雙精度。我已經做了一些自我調試，並發現當它將蝙蝠的次數除以命中次數時，計算會產生混亂。如果有人能幫我弄清楚這個問題，我會很感激。

//libaries 
#include <iostream> 
#include <string> 
#include <sstream> 
#include <iomanip> 
using namespace std; 

class battingAverage 
{ 
public: 

    string pName; 
    int nBats; 
    int tHits; 
    int gPlayed; 
    int gcalled; 
    double average; 
    double average1; 
    double playeraverage; 

}; 

int main() 
{ 
    string numberPlayers; 
    int nplayers; 
//enters the number of players the user wants to enter data for 
cout << "Enter the number of players you want to enter data for: "; 
cin >> numberPlayers; 
cout << endl; 

//converts the value of numberPlayers to nplayers 
istringstream convert(numberPlayers); 

//sets integer nplayers equal to the value of the string numberPlayers 
if(! (istringstream(numberPlayers) >> nplayers)) 
{ 
    nplayers = 0; 
} 

cout << "This program calculates the batting average of baseball players.\nYou may enter data for " << nplayers << " players." << endl; 

battingAverage ba[nplayers]; 

int index = 0; 

//while statement to get data 
while(index < nplayers) 
{ 
    cout << "Enter the players last name: " << endl; 
    cin >> ba[index].pName; 

    cout << "Enter the number of games the player played: " << endl; 
    cin >> ba[index].gPlayed; 
    cout << ba[index].gPlayed << endl; 

    cout << "Enter the number of games the player was called in for: " << endl; 
    cin >> ba[index].gcalled; 
    cout << ba[index].gcalled << endl; 

    cout << "Enter the number of times the player was at bat: " << endl; 
    cin >> ba[index].nBats; 
    cout << ba[index].nBats << endl; 

    cout << "Enter the number of time the player hit: " << endl; 
    cin >> ba[index].tHits; 
    cout << ba[index].tHits << endl; 

    if(ba[index].tHits > ba[index].nBats) 
    { 
    cout << "Enter a valid value for the number of times the player hit: "; 
    cin >> ba[index].tHits; 
    } 

    cout << endl; 
    index++; 

} 

//rounds average to 3 decimal places 
cout << fixed << setprecision(3); 
//average formula 
ba[index].playeraverage = (ba[index].nBats/ba[index].tHits) * (ba[index].gPlayed/ba[index].gcalled);//error 
cout << ba[index].playeraverage << endl << endl;//just temp line to check calculation of average. 

ba[index].average = .000; 
ba[index].average1 = .099; 

while(ba[index].average < 1 && ba[index].average1 < .899) 
{ 
    ba[index].average +=.100; 
    ba[index].average1 += .1; 
    //prints chart 
    cout << setprecision(1) << ba[index].average << "00" << setprecision(3) << setw(12) << ba[index].average1 << endl; 
    } 

cout << "1.000" << setw(12) << "1.000" << endl; 

//version of system pause 
cout << "\nPress enter to continue..."; 
cin.sync(); 
cin.ignore(); 
return 0; 

}

Answer 1

在計算過程中，您的索引值是錯誤的。

我馬上發現這是我把你的代碼在調試器，並通過它加強，有些東西你真的應該做自己。

您從int index = 0;開始，並在用戶輸入每個玩家的數據時增加它。 在輸入循環結束時，索引現在與玩家數量相同。
（例如，如果你有5名球員，指數目前是5，玩家的數據存儲在ba[0]，ba[1]，ba[2]，ba[3]和ba[4]）

注意，在這一點上ba[5]是不有效的數據。但那正是ba[index]！

你對ba[index]做了所有的計算，這是無效的數據，你想知道爲什麼你會得到毫無意義的結果？

我建議你在開始計算之前將索引設置回0，然後再做一個循環，爲每個玩家進行必要的計算0 ... 4。

Answer 2

在此行中：因爲這兩個nBats和tHits是整數，您只使用整數運算

(ba[index].nBats/ba[index].tHits) 

：

ba[index].playeraverage = (ba[index].nBats/ba[index].tHits) * (ba[index].gPlayed/ba[index].gcalled);//error 

你有這樣的表達。
答案將是一個整數。

例如：
nBats = 10 & tHits = 3，你所期望的表達是3.333。再以約gPlayed和gcalled表達

((double)ba[index].nBats/ba[index].tHits) 

同一件事：
，但只會是3

爲了解決這個問題，我建議改變來。