How can you open a text file and append all its lines to another text file in C++? I find mostly solutions for separate reading from a file to a string, and writing from a string to a file. Can this elegantly be combined?
It is not always given that both files exist. There should be a bool return when accessing each of the files.
I'm sorry if this is already off-topic: Is appending text content to a file conflict-free in the meaning that multiple programs can do this simultaneously (the order of the lines DOESN'T matter) ? If not, what would be an (atomic) alternative?
I can only speak for opening a file and appending it to another file:
std::ifstream ifile("first_file.txt");
std::ofstream ofile("second_file.txt", std::ios::app);
//check to see that the input file exists:
if (!ifile.is_open()) {
//file not open (i.e. not found, access denied, etc). Print an error message or do something else...
}
//check to see that the output file exists:
else if (!ofile.is_open()) {
//file not open (i.e. not created, access denied, etc). Print an error message or do something else...
}
else {
ofile << ifile.rdbuf();
//then add more lines to the file if need be...
}
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