如何从整个代码的函数中打开文件

How do I open a file from a function for the whole code?

本文关键字：函数 文件 代码      更新时间：2023-10-16

我正在研究一个简单的 c++ 脚本，并希望将打开文件的整个过程放在函数中。但是，当我尝试时，我的主函数出现错误。谁能帮我？这是我的代码：

#include <iostream>
#include <fstream>
#include <string>
#include <iomanip>
using namespace std;
string openFile(string fileName);
int main(void)
{
    string fileName;
    cout << "Please input the file name (including the extension) for this code to read from." << endl;
    cin >> fileName;
    openFile(fileName);
    fout << "File has been opened" << endl;
    return 0;
}
string openFile(string fileName)
{
    ifstream fin(fileName);
    if (fin.good())
    {
        ofstream fout("Output");
        cout << fixed << setprecision(1);
        fout << fixed << setprecision(1);
        //Set the output to console and file to be to two decimal places and 
        //not in scientific notation
    }
    else 
    {
        exit(0);
    }
}

    #include <iostream>
    #include <fstream>
    #include <string>
    #include <iomanip>
    using namespace std;
    ofstream fout;
    string openFile(string fileName);
    void closeFile();
    int main(void)
    {
        string fileName;
        cout << "Please input the file name (including the extension) for this code to read from." << endl;
        cin >> fileName;
        openFile(fileName);
        if (fout.good()) //use fout in any way in this file by cheking .good()
           cout << "File has been opened" << endl;
        closeFile();
       return 0;
    }
    string openFile(string fileName)
    {
        cout << fixed << setprecision(1);
        fout.open(fileName.c_str());
        if (fout.good()) {
           fout << fixed << setprecision(1);
           cout<<"Output file opened";
        }
    }
    void closeFile()
    {
       fout.close();
    }

你的代码有很多缺陷，

  1. fout << "File has been opened" << endl;，应该是，

    cout << "File has been opened" << endl;

  2. 您不能再次重新修饰相同的变量。

    ofstream fout("Output");// first 
cout << fixed << setprecision(1);
fout << fixed << setprecision(1);
//Set the output to console and file to be to two decimal places and 
//not in scientific notation
ofstream fout("Tax Output.txt");//second

在最后一行为变量指定一些其他名称。

  1. 你正在通过std::string，你应该通过const char *的地方，

ifstream fin(fileName) ;

应该是，

ifstream fin(fileName.c_str());
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