How do you open a file in C++?

Question

I want to open a file for reading, the C++ way. I need to be able to do it for:

• text files, which would involve some sort of read line function.

Answer 1

There are three ways to do this, depending on your needs. You could use the old-school C way and call fopen/fread/fclose, or you could use the C++ fstream facilities (ifstream/ofstream), or if you're using MFC, use the CFile class, which provides functions to accomplish actual file operations.

All of these are suitable for both text and binary, though none have a specific readline functionality. What you'd most likely do instead in that case is use the fstream classes (fstream.h) and use the stream operators (<< and >>) or the read function to read/write blocks of text:

int nsize = 10;
char *somedata;
ifstream myfile;
myfile.open("");
myfile.read(somedata,nsize);
myfile.close();

Note that, if you're using Visual Studio 2005 or higher, traditional fstream may not be available (there's a new Microsoft implementation, which is slightly different, but accomplishes the same thing).