C ++中的Ofstream数组 [英] Array of Ofstream in c++

问题描述

我希望在我的项目中使用41个输出文件来在它们上写文本.首先创建一个字符串数组list来命名这些输出文件，然后我尝试定义ofstream对象的数组并使用list来命名它们，但是出现此错误'outfile' cannot be used as a function.下面是我的代码:

I want 41 output files to use in my project to write text on them. first create a string array list to name those output files then I tried to define an array of ofstream objects and use list to name them, but I get this error that 'outfile' cannot be used as a function. Below is my code:

#include <sstream>
#include <string>
#include <iostream>
#include <fstream>
using namespace std ;
int main ()
{
  string list [41];
  int i=1;
  ofstream *outFile = new ofstream [41];

  for (i=1;i<=41 ;i++)
  {
    stringstream sstm;
    sstm << "subnode" << i;
    list[i] = sstm.str();
  }

  for (i=0;i<=41;i++)
    outFile[i] (list[i].c_str());

  i=1;
  for (i=1;i<=41;i++)
    cout << list[i] << endl;

  return 0; 
}

推荐答案

请参见以下修补程序:

1. 请勿使用new，除非您必须这样做(泄漏所有文件并且未正确销毁它们会导致数据丢失；如果未正确关闭它们，则未刷新ofstreams，以及未决的输出缓冲区将会丢失)
2. 使用正确的数组索引(从0开始！)
3. 在默认构造的 ofstream上调用.open(...)打开文件
4. 建议:
   • 我建议不要使用using namespace std;(以下未更改)
   • 我建议重用stringstream.这是一个好习惯
   • 首选使用C ++样式的循环索引变量(for (int i = ....).这样可以防止i范围过大带来的意外.
   • 实际上，与时俱进，并在一定范围内使用

1. don't use new unless you have to (you were leaking all files and not properly destructing them will lead to lost data; ofstreams might not be flushed if you don't close them properly, and the pending output buffer will be lost)
2. Use proper array indexing (starting from 0!)
3. Call .open(...) on a default-constructed ofstream to open a file
4. Recommendations:
   • I'd recommend against using namespace std; (not changed below)
   • I recommend reusing the stringstream. This is is good practice
   • Prefer to use C++-style loop index variables (for (int i = ....). This prevents surprises from i having excess scope.
   • In fact, get with the times and use ranged for

#include <sstream>
#include <string>
#include <iostream>
#include <fstream>
using namespace std;
int main ()
{
    ofstream outFile[41];

    stringstream sstm;
    for (int i=0;i<41 ;i++)
    {
        sstm.str("");
        sstm << "subnode" << i;
        outFile[i].open(sstm.str());
    }

    for (auto& o:outFile)
        cout << std::boolalpha << o.good() << endl;
}

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