C programming/stdio.h/perror

The POSIX error function, perror, is used in C and C++ to print an error message to stderr, based on the error state stored in errno.http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf ISO/IEC 9899:1999 specification p. 305, § 7.19.10.2It prints str and an implementation-defined error message corresponding to the global variable errno. History The definition of perror was first released in Issue 1 of the System V Interface Definition. Usage Inclusion #include <stdio.h> Declaration void perror(const char* prefix); Example int fd = open("/etc/passwd", O_RDONLY); if (fd == -1) { perror("open"); exit(1); } Semantics If the parameter prefix is non-NULL, perror will first print prefix followed by a colon and a space to standard error. Then, it will print the result of strerror to standard error, followed by a newline character. For instance the above example may print open: Permission denied References External links C++ reference for std::perror deep