C Primer Plus, Fourth Edition

Standard I/O

The standard I/O package has two advantages, besides portability, over low-level I/O. First, it has many specialized functions that simplify handling different I/O problems. For example, printf() converts various forms of data to string output suitable for terminals. Second, input and output are buffered. That is, information is transferred in large chunks (typically 512 bytes at a time or more) instead of a byte at a time. When a program reads a file, for example, a chunk of data is copied to a buffer—an intermediate storage area. This buffering greatly increases the data transfer rate. The program can then examine individual bytes in the buffer. The buffering is handled behind the scenes, so you have the illusion of character-by-character ...