从文件输入到类对象数组中C++

Question

我不知道如何输入我的数据。对不起，我是一个noob，我发现这样的唯一例子太复杂了，我不明白发生了什么。我知道这甚至不是很正确，但我不知道如何设置来自文件的输入。我的文件中的数据是这样的：

986 8 
432 24 
132 100 
123 89 
329 50 
503 30 
783 78 
822 32 
233 56 
322 74 

而且我的计划，到目前为止是这样的：

#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"); 

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

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

    // 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 
    pos = 0; 
    while(NUMOFPROD > pos++ && infile >> products[pos]) 
    { 
     id = products[pos]; 
     products[pos].getId(id); 


     //products[pos].getAmount(total); 
    } 
    infile.close(); 
    // 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 
    pos = 0; 
    while(NUMOFPROD > pos++) 
    { 
     products[pos].display(); 
    } 

    return 0; 

} 


// Write the implementations for all the member functions of the class. 

void getId(int item) 
{ 
    itemNumber = item; 

} 
void getAmount(int num) 
{ 
    numOfItem = num; 
} 
void display() 
{ 
    cout << itemNumber << " "; 
} 

Answer 1

输入和从一个文件，这样做：

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

int main() 
{ 
    ifstream fin("YourTxtFile.txt"); 
    fin >> something //Fin acts just like your standard cin 

    fin.close() //Don't forget to close the stream when you're done! 
} 

如果你想

输出到文件，请执行以下操作：

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

int main() 
{ 
    ofstream fout("YourTxtFile.txt"); 
    fout >> something //Fout acts just like your standard cout 

    fout.close() //Don't forget to close the stream when you're done! 
} 

你也可以同时做到这一点！

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

int main() 
{ 
    ifstream fin("YourTxtFile1.txt"); 
    fin >> something //Fin acts just like your standard cin 

    fin.close() //Don't forget to close the stream when you're done! 

    ofstream fout("YourTxtFile2.txt"); 
    fout >> something //Fout acts just like your standard cout 

    fout.close() //Don't forget to close the stream when you're done! 
} 

只是为了让你知道，fin和fout可以调用任何你想要的。

如果这篇文章回答你的问题，请将其标记为答案。

谢谢