For C/C++ routines, output from the printf function is directed to stdout, which is associated with SYSPRINT. All C/C++ runtime messages and perror() messages are directed to stderr. stderr corresponds to the ddname associated with the Language Environment MSGFILE runtime option. The destination of the printf function output can be changed by using the redirection 1>&2 at routine invocation to redirect stdout to the stderr destination. Both streams can be controlled by the MSGFILE runtime option.