The GNU C++ Iostream Library

Chapter 6: C Input and Output

libio is distributed with a complete implementation of the ANSI C stdio facility. It is implemented using streambuf objects. See Stdiobuf.

The stdio package is intended as a replacement for the whatever stdio is in your C library. Since stdio works best when you build libc to contain it, and that may be inconvenient, it is not installed by default.

Extensions beyond ANSI:

• A stdio FILE is identical to a streambuf. Hence there is no need to worry about synchronizing C and C++ input/output---they are by definition always synchronized.
• If you create a new streambuf sub-class (in C++), you can use it as a FILE from C. Thus the system is extensible using the standard streambuf protocol.
• You can arbitrarily mix reading and writing, without having to seek in between.
• Unbounded ungetc() buffer.