如何将文本附加到 C++ 中的文本文件？

How to append text to a text file in C++?

提问by Ahmad Farid

How to append text to a text file in C++? And create a new text file if it does not already exist and append text to it if it does exist.

如何将文本附加到 C++ 中的文本文件？如果尚不存在，则创建一个新文本文件，如果存在，则将文本附加到其中。

回答by Bertrand Marron

You need to specify the append open mode like

您需要指定附加打开模式，如

#include <fstream>

int main() {  
  std::ofstream outfile;

  outfile.open("test.txt", std::ios_base::app); // append instead of overwrite
  outfile << "Data"; 
  return 0;
}

回答by Shital Shah

I use this code. It makes sure that file gets created if it doesn't exist and also adds bit of error checks.

我用这个代码。它确保在文件不存在时创建该文件，并添加一些错误检查。

static void appendLineToFile(string filepath, string line)
{
    std::ofstream file;
    //can't enable exception now because of gcc bug that raises ios_base::failure with useless message
    //file.exceptions(file.exceptions() | std::ios::failbit);
    file.open(filepath, std::ios::out | std::ios::app);
    if (file.fail())
        throw std::ios_base::failure(std::strerror(errno));

    //make sure write fails with exception if something is wrong
    file.exceptions(file.exceptions() | std::ios::failbit | std::ifstream::badbit);

    file << line << std::endl;
}

回答by Osaid

 #include <fstream>
 #include <iostream>

 FILE * pFileTXT;
 int counter

int main()
{
 pFileTXT = fopen ("aTextFile.txt","a");// use "a" for append, "w" to overwrite, previous content will be deleted

 for(counter=0;counter<9;counter++)
 fprintf (pFileTXT, "%c", characterarray[counter] );// character array to file

 fprintf(pFileTXT,"\n");// newline

 for(counter=0;counter<9;counter++)
 fprintf (pFileTXT, "%d", digitarray[counter] );    // numerical to file

 fprintf(pFileTXT,"A Sentence");                   // String to file

 fprintf (pFileXML,"%.2x",character);              // Printing hex value, 0x31 if character= 1

 fclose (pFileTXT); // must close after opening

 return 0;

}

回答by vveil

You could also do it like this

你也可以这样做

#include <fstream>

int main(){   
std::ofstream ost {outputfile, std::ios_base::app};

ost.open(outputfile);
ost << "something you want to add to your outputfile";
ost.close();
return 0;
}

回答by Tom

I got my code for the answer from a book called "C++ Programming In Easy Steps". The could below should work.

我从一本名为“C++ Programming In Easy Steps”的书中得到了答案的代码。下面的可能应该工作。

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

using namespace std;

int main()
{
    ofstream writer("filename.file-extension" , ios::app);

    if (!writer)
    {
        cout << "Error Opening File" << endl;
        return -1;
    }

    string info = "insert text here";
    writer.append(info);

    writer << info << endl;
    writer.close;
    return 0;   
} 

I hope this helps you.

我希望这可以帮助你。

回答by ranu

You could use an fstreamand open it with the std::ios::appflag. Have a look at the code below and it should clear your head.

您可以使用 anfstream并用std::ios::app标志打开它。看看下面的代码，它应该会让你清醒。

...
fstream f("filename.ext", f.out | f.app);
f << "any";
f << "text";
f << "written";
f << "wll";
f << "be append";
...

You can find more information about the open modes hereand about fstreams here.

你可以找到关于开放模式的详细信息，在这里和有关fstreams这里。