並保存到數組C++

Question

我在做這個節目將從文件和存儲無論是文件到一個數組中讀取和將打印，像這樣：

項目數986有在庫存8項

項目號碼432具有在坯料24項

項目號碼132具有在庫存100級的物品

項目號碼123具有在庫存89項

項目編號329在庫存50項

項目號碼503具有在庫存30項

項目編號783在庫存78項

項目編號822在庫存

項目32個項目數字233有庫存56項

項目編號322的股票74項

我不知道爲什麼我得到對所有值取0，而不是上面那些值。有任何想法嗎？

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


// This program defines a class called Inventory that has itemnumber (which 
// contains the id number of a product) and numofitem (which contains the 
// quantity on hand of the corresponding product)as private data members. 
// The program will read these values from a file and store them in an 
// array of objects (of type Inventory). It will then print these values 
// to the screen. 

// Example: Given the following data file: 
//  986 8 
//  432 24 
// This program reads these values into an array of objects and prints the 
// following: 
//  Item number 986 has 8 items in stock 
//  Item number 432 has 24 items in stock 


const int NUMOFPROD = 10; // This holds the number of products a store sells 

class Inventory 
{ 
public: 

    void getId(int item);  // This puts item in the private data member 
           // itemnumber of the object that calls it. 
    void getAmount(int num); // This puts num in the private data member 
           // numofitem of the object that calls it. 
    void display();   // This prints to the screen 
           // the value of itemnumber and numofitem of the 
           // object that calls it. 
private: 

    int itemNumber;   // This is an id number of the product 
    int numOfItem;   // This is the number of items in stock 

}; 


int main() 
{ 

    ifstream infile;  // Input file to read values into array 
    infile.open("Inventory.dat"); 

    Inventory products[NUMOFPROD]; // Fill in the code that declares an array of objects of class Inventory 
    // called products. The array should be of size NUMOFPROD 

    int pos;     // loop counter 
    int id=0;     // variable holding the id number 
    int total=0;     // variable holding the total for each id number 


    for (int pos = 0; pos < NUMOFPROD; pos++){ 
     infile >> products[pos].getId(id); 
     infile >> products[pos].getAmount(total); 
    } // Fill in the code that will read inventory numbers and number of items 
    // from a file into the array of objects. There should be calls to both 
    // getId and getAmount member functions somewhere in this code. 
    // Example: products[pos].getId(id); will be somewhere in this code 

    for (int pos = 0; pos < NUMOFPROD; pos++){ 
     products[pos].display(); 
    }// Fill in the code to print out the values (itemNumber and numOfItem) for 
    // each object in the array products. 
    // This should be done by calling the member function display within a loop 

    return 0; 

} 

// Write the implementations for all the member functions of the class. 
void Inventory::getId(int item){ 
    itemNumber = item; 
} 

void Inventory::getAmount(int num){ 
    numOfItem = num; 
} 

void Inventory::display(){ 
    cout << "Item number " << itemNumber << " has " << numOfItem << " items in stock\n"; 
} 

Answer 1

取而代之的是：

infile >> products[pos].getId(id); 
infile >> products[pos].getAmount(total); 

我相信你想

infile >> id; 
products[pos].getId(id); 
infile >> total; 
products[pos].getAmount(total); 

好時間的方式重命名getId到setId。

Answer 2

infile >> products[pos].getId(id); 

這使用了容易混淆的命名getId函數來設置值到的id，這是零。然後它嘗試讀入該函數的返回值，由於沒有返回值，這會導致編譯錯誤。我不知道爲什麼你的編譯器接受這個代碼。

讀取和設置的值，你想

infile >> id; 
products[pos].getId(id); 

你可能會考慮重新命名的功能類似setId，除非你的目標是混淆代碼的讀者。