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:
-
Read an entire file at once
std::string tfile::read(char const* filename) -
Write a sequence of bytes in memory to a file
size_t write(char const* filename, char const* data, size_t length) -
Write a null-terminated string to a file
size_t write(char const* filename, char const* data) -
Write a std::string to a file
size_t write(char const* filename, const std::string& s) -
Write a container of strings, adding line endings
template <typename C> size_t writeLines(const char* filename, C); -
Write a begin, end range of strings, adding line endings
template <typename It> size_t writeLines(const char* filename, It begin, It end); -
Get the size in bytes of a file
size_t tfile::size()
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");
// Writes a file with three lines, using the line endings of the platform
tfile::writeLines("myfile.txt", {"line1", "line2", "line3"});
File Openers are for applications which need to keep a file open for processing. File Openers are a thin wrapper over the C file handle type FILE*, which is the basis of I/O in C and C++.
A 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 File 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); // at most 10
// You can't write a reader, so this won't compile:
// reader.write("hello");
// Open a file, appear a line, close it.
tfile::Appender("myfile2.txt").writeLine("a new line");
// You can't read an Appender, so this won't compile:
// tfile::Appender("myfile2.txt").read();
// Iterate through lines.
std::string line;
while (reader.readLine(line)) {
// Do things to `line` here
}
// Another way to do that:
reader.forEachLine([] (const std::string& line) {
// Do things to `line` here
});