tide999 / tfile

tiny C++11 file utilities

tfile - tiny C++11 file utilities

tfile is a tiny header-only library for C++11 and beyond which offers a small number of essential features:

• functions to read a whole file at once, write a whole file at once, and get the bytesize of a file;

• and Openers: zero-cost abstractions that wrap C's FILE* classic file handle

The functions

• std::string tfile::read(char const* filename)
• size_t write(char const* filename, char const* data, size_t length)
• size_t write(char const* filename, char const* data)
• size_t write(char const* filename, const std::string& s)
• size_t tfile::size() returns the byte size of a file.

Examples of usage:

auto data = tfile::read("myfile.txt");
data += "another line\n";
tfile::write("myfile.txt", data);
std::cout << "myfile.txt: filesize=" << tfile::size("myfile.txt");

Openers

Openers are for applications which need to keep a file open for processing. Openers are a thin wrapper over the C file handle type FILE*, which is the basis of I/O in C and C++.

An File Opener offers these advantages over a raw FILE*:

• Automatically closes the FILE* in its destructor
• Prevents impossible reads or writes at compile time
• Throws an exception if the file won't open and exceptions are enabled
• Can iterate one line at a time

"Impossible reads or writes" means that there is nothing in C or C++ to prevent writing code to, say, read from a write-only file handle - it will simply return an error at runtime - but a File Opener provides read or write methods only if they actually work, so these errors can be caught at compile-time.

There are six Openers, corresponding to the six modes in which files can be opened:

• tfile::Reader: read-only, position at start of file - mode "r"
• tfile::ReaderWriter: read-write, position at start of file - mode "r+"
• tfile::Writer: write-only, truncate file to empty - mode "w"
• tfile::TruncateReaderWriter: read-write, truncate to empty - mode "w+"
• tfile::Appender: write-only, position at end of file - mode "a"
• tfile::ReaderAppender: read-write, position at end of file - mode "a+"

For the exact signatures of methods, see the file tfile.h.

For more information on file opening modes, see http://man7.org/linux/man-pages/man3/fopen.3.html

Examples of usage:

tfile::Reader reader("myfile2.txt");
std::string s(10);
auto bytes_read = reader.read(s);   // read at most 10 chars
// reader.write("hello");  // Won't compile

tfile::Appender("myfile2.txt").write("a new line\n");
// tfile::Appender("myfile2.txt").read();  // won't compile

while (true) {
    auto line = reader.readLine();
    if (line.empty())
        break;
    // ...
}