c++ - 我正在使用C++，需要帮助来识别代码中的错误

Question

我的outfile似乎正在正确写入，但是infile正在读取垃圾值。

#include <iostream>
#include <string>
#include <fstream>

using namespace std;

int main()
{
int count;

ifstream infile;
infile.open("accounts.txt");

ofstream outfile;
outfile.open("accounts.txt");

cout<<"Read from file"<<endl;
infile>>count;
cout<<count<<endl;
cout<<"Write in file"<<endl;
outfile<<count;
cout<<count;

infile.close();
outfile.close();
return 0;
}

输出如下:

Read from file
4255273
Write in file
4255273

Answer 1

您的代码正在尝试同时打开和访问同一文件，作为输入流和输出流。这行不通!

您应该重新排列代码，以便将其打开以进行输入，进行输入，然后将其关闭。只有这样，您才能重新打开它以进行输出。

这是一个建议:

int main()
{
    int count;

    ifstream infile;
    infile.open("accounts.txt");  // First, open for input...
    cout << "Read from file" << endl;
    infile >> count;              // ... and read the data
    cout << count << endl;
    infile.close();               // Done reading: close it!

    ofstream outfile;
    outfile.open("accounts.txt"); // Now, open for output...
    cout << "Write in file" << endl;
    outfile << count;             // ... do the output...
    cout << count;
    outfile.close();              // ... and close it.

    return 0;
}