Question

我正在研究一个大学项目，它要求我在文本文件中找到一个值并将其替换为我存储在float变量中的新值，部分问题是我不知道需要替换的项目，只有它的位置（例如，我可以搜索0.00的值，但多个记录可以有这种平衡）。

文本文件的布局如下：

USERNAME1
  密码1
  AccountNo1
  余额1
  Jimmy54
  FooBar123
  098335
  13.37
  ...

我的代码的相关部分如下所示：

用户输入他们的用户名，我们将其存储在enteredName

中

#include "stdafx.h"
#include <iostream>
#include <string>
#include <fstream>
using namespace std;

int _tmain(int argc, _TCHAR* argv[])
{

    cout << "Please enter your username:\n";
    cin >> enteredName;

我们在代码中大约有100行代表这个问题的重要部分：

        if (c2 == 1)
        {
            //irrelevant to problem
        }
        else if (c2 == 2) 
        {
            float convBal;
            float deposit;
            string newBal;

            convBal = ::atof(ball.c_str()); 

             /* Ball is declared higher up in the code and just contains a 
                value pulled from the text file for the sake of the question 
                we'll say it has a value of 0.00 */

            cout << "How much would you like to deposit?:\n";
            cin >> deposit;

            newBal= convBal + deposit;

            cout << "Your total balance is now: "<< newBal << "\n\n";

        } 
}

那么从这里开始需要做的是打开文件，在文件中搜索enteredName（在这种情况下我们会说Jimmy54），然后将用户名（13.37）下面的3行替换为newBal中存储的值

提前致谢！对不起，如果这听起来像一个愚蠢的问题，我对编程很新，甚至更新的c ++

编辑＃1： 这是我到目前为止的代码，它找到了incomingName，然后得到以下3行：

if (myfile.is_open())
{
    while (getline(myfile, line))
    {
        if (line.compare(enteredName) == 0)
        {
            getline(myfile, line); //Password
            getline(myfile, line); //Account Number
            getline(myfile, line); //Balance
        }
    }
}
myfile.close();

Answer 1

这是解决我的问题的代码，它有点草率但它有效！

它只是读入一个新文件并进行任何更改，然后再次回写。

if (myfile.is_open())
{
    while (getline(myfile, line))
    {
        if (line.compare(enteredName) == 0)
        {
            tempFile << enteredName << "\n"; //Username
            getline(myfile, line);
            tempFile << line << "\n"; //Password
            getline(myfile, line);
            tempFile << line << "\n"; //Account Number
            getline(myfile, line);
            tempFile << newBal << "\n"; //Balance
        }
        else
        {
            tempFile << line << "\n"; //Username
            getline(myfile, line);
            tempFile << line << "\n"; //Password
            getline(myfile, line);
            tempFile << line << "\n"; //Account Number
            getline(myfile, line);
            tempFile << line << "\n"; //Balance
        }

    }
}
myfile.close();
tempFile.close();


/* Had to declare these again beacuse the compiler was throwing some bizarre error when using the old declarations */
ifstream tempF("TempStore.csv");
ofstream mainF("DataStore.csv", ios::trunc);

//Writes back from TempStore to DataStore with changes made correctly
if (tempF.is_open())
{
   while (getline(tempF, line))
   {
     mainF << line << "\n"; //Username
     getline(tempF, line);
     mainF << line << "\n"; //Password
     getline(tempF, line);
     mainF << line << "\n"; //Account Number
     getline(tempF, line);
     mainF << line << "\n"; //Balance
   }
}
tempF.close();
mainF.close();

如何在文本文件中找到一行并替换它？

1 个答案: