In computer programming, the fopen, with related functions fdopen and freopen, is one of the basic functions in the C programming language. Because it is so popular, many script languages derived from C tend to provide the same function with the same or similar functionality. It is considered higher-level than the open system call of UNIX operating systems.
They are defined as.
FILE * fopen(const char *path, const char *mode);FILE * fdopen(int fildes, const char *mode);FILE * freopen(const char *path, const char *mode, FILE * restrict stream);
In some libraries, mode can include a letter b, which indicates the given file is a binary file. Without that, a sequence of carriage return and line feed is automatically regarded as a line feed. See new line for new line issues.