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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

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

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
});