C/C++ Programmer's Guide (G06.27+, H06.08+, J06.03+)

For information on how to recognize the diagnostic that is printed by the assert() function and
information on the termination behavior of the assert() function, see the assert() function in the
Guardian TNS C Library Calls Reference Manual.
These characters are tested for by the isalnum(), isalpha(), iscntrl(), islower(),
isprint(), and isupper() functions:
• isalnum() returns true for characters a–z, A–Z, 0–9
• isalpha() returns true for characters a–z, A–Z
• iscntrl() returns true for values 0–31, 127
• islower() returns true for characters a–z
• isprint() returns true for values 32–126
• isupper() returns true for characters A–Z
An undefined value is returned by the mathematics functions after a domain error, and errno is
set to EDOM.
The mathematics functions set the integer expression errno to the value of the macro ERANGE on
underflow range errors.
When the fmod() function has a second argument of zero, fmod() returns the value of the first
argument (that is zero is treated as one).
Signals
For the set of signals for the Guardian signal() function and a description of the parameters
and the usage of each signal, see the Guardian TNS C Library Calls Reference Manual.
For the set of signals for the OSS signal() function and a description of the parameters and the
usage of each signal, see the signal(4) reference page online or in the Open System Services
System Calls Reference Manual.
For each signal recognized by the signal() function, at program startup the handler SIG_DFL is
registered for the all the signals by the C runtime.
The default handling is reset if a SIGILL signal is received by a handler specified to the signal()
function.
Streams and Files
The last line of a text stream does not require a terminating newline character. The file is written
with the characters requested.
The space characters that are written out to a text stream immediately before a newline character
appear when the stream is read back in.
Zero null characters may be appended to data written to a binary stream.
The file position indicator of an append mode stream is initially positioned at the start of the file.
A write on a text stream does not cause the associated file to be truncated beyond that point.
Full buffering best describes the file buffering of the TNS C run-time.
A zero-length file can actually exist.
These are the rules for composing a valid file name:
• In the Guardian environment, the file name is formed as specified by the Guardian file-name
format, which is composed of system name, volume name, subvolume name and file name,
each separated by a period(.). Except for the file name, all the other fields can be omitted,
then the default sub-volume is the present working subvolume.
• In the OSS environment on NonStop S-series systems, the newline file name must be a valid
OSS filename.
The same file can be opened simultaneously multiple times, as long as it is not for writing.
The effect of the remove() function on an open file is that it returns a nonzero value and does
not remove the file.
Implementation-Defined Behavior of TNS C 411