c++ - 将名称和数字输出到文件 C++

Question

我的程序能够记录您输入的所有名称和数量“数字”并显示到屏幕上，我遇到的问题是将所有这些数字和名称保存到一个文件中。

它似乎只记录并保存你最后输入的单词和数字到文件中。例如你输入 4 个名字和 4 个不同的数字，它只会保存输入的姓氏和数字，而不保存输入的第一个。

#include <iostream>
#include <string>
#include <sstream>
#include <algorithm>
#include <vector>
#include <fstream>

using namespace std;

struct bank_t {
  string name;
  int money;
} guests[100];  // **guests name = maximum number of names to enter**

void printcustomer (bank_t nombres);  // **bank_t nombres = names**

int main ()
{
  string amount;  //** amount to enter**
  int n;
  int i;  //** number of customers **
  //int i=3;
    cout<<"Please enter the amount of customers";
    cout<<" then press 'ENTER' \n";
    cin >> i;  // **will take what ever amount of names you decide to input **
    cin.get();

  for (n=0; n<i; n++)
  {

    cout << "\n Enter the name of customer: \n";
    getline (cin,guests[n].name);
    cout << "\n Enter the amount of money: \n $: ";
    getline (cin,amount);
    stringstream(amount) >> guests[n].money;
  }

  cout << "\n You have entered these names:\n";
  for (n=0; n<i; n++)
    printcustomer (guests[n]);

  return 0;
}

void printcustomer (bank_t nombres)
{

    cout << nombres.name;  //** display the final names **
    cout << "  $" << nombres.money << " Dollars"<< "\n"; //** display the final amount **

    ofstream bank_search;
    bank_search.open ("alpha.dat");
    //bank_search.write << nombres.name ;
    bank_search << nombres.money;
    bank_search.close();    

}

Answer 1

It seems that it only records and saves the last words and numbers you input into a file.

您正在为每条要写入的记录打开和关闭文件，并覆盖之前写入的记录!

您需要以附加模式打开您的文件(参见 std::ios_base::app )，或者在 main() 的循环外打开它一次，并传递 ofstream 作为每个 printcustomer() 函数调用的参数(这会执行得更好)。

void printcustomer (bank_t nombres)
{

    cout << nombres.name;  //** display the final names **
    //** display the final amount **
    cout << "  $" << nombres.money << " Dollars"<< "\n"; 

    ofstream bank_search;
    bank_search.open ("alpha.dat", std::ios_base::app); // Note the append mode!
    //bank_search.write << nombres.name ;
    bank_search << nombres.money;
    bank_search.close();    

}

如图所示，这样做效率不高，因为打开和关闭文件是一项成本相对较高的操作。更好的解决方案是打开文件一次并附加所有新输入的记录:

ofstream bank_search("alpha.dat", std::ios_base::app);

cout << "\n You have entered these names:\n";
for (n=0; n<i; n++)
{
    printcustomer (bank_search,guests[n]);
}
bank_search.close();    

---

void printcustomer (ofstream& bank_search, bank_t nombres)
{
    bank_search << nombres.name;
    bank_search << nombres.money;
}