如何在c++中追加文本到文本文件?如果它不存在，则创建一个新的文本文件，如果它存在，则向其追加文本。
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;
}
#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;
}
我使用这个代码。它确保在文件不存在时创建该文件，并添加了一些错误检查。
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;
}
你可以使用fstream并使用std::ios::app标志打开它。看看下面的代码，应该会让你头脑清醒。
...
fstream f("filename.ext", f.out | f.app);
f << "any";
f << "text";
f << "written";
f << "wll";
f << "be append";
...
你可以在这里找到更多关于开放模式的信息，在这里找到关于fstreams的信息。
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;
}
