In [[computerC programming language|C programming]], the <code>'''fopen'''</code> function is one of the basic functions in the [[stdio.h]] file of the [[C programmingstandard languagelibrary]]. It returns an [[I/O]] [[stream]] attached to the specified [[computer file|file]] or other device from which reading and writing can be done. If the function fails, it returns 0. Because the functionality is so useful, many languages derived from C provide functions of the same name, with the same or similar function: for example, [[PHP]]. <code>fopen</code> is considered higher-level than the <code>open</code> [[system call]] of UNIX operating systems. The related C library function '''<code>freopen</code>''' performs the same operation after first closing any open stream associated with its parameter.
