[英]Read from file and save into array c++
我正在执行此程序,该程序将从文件读取并将文件中的任何内容存储到数组,并且它将打印如下内容:
编号986的库存为8
物料号432有24件库存
物料号132有100个库存
物料编号123库存89
物料编号329有50件库存
物料编号503有30件库存
物料号783有78件库存
物料号822有32件库存
物料号233库存56
物料号322有74件库存
我不知道为什么对于所有值而不是上面的那些值都得到0。 有任何想法吗?
#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";
}
代替这个:
infile >> products[pos].getId(id);
infile >> products[pos].getAmount(total);
我相信你想要
infile >> id;
products[pos].getId(id);
infile >> total;
products[pos].getAmount(total);
顺便说一句,将getId
重命名为setId
的好时机。
infile >> products[pos].getId(id);
这使用名称混乱的getId
函数将值设置为id
的值,该值为零。 然后,它尝试读入该函数的返回值,这将导致编译错误,因为没有返回值。 我不知道为什么您的编译器会接受该代码。
要读取和设置值,您需要
infile >> id;
products[pos].getId(id);
您可能会考虑将函数重命名为类似setId
,除非您的目标是使代码的读者迷惑。
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