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Oracle® Developer Studio 12.6: C User's Guide

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Updated: July 2017

2.13 Predefined Names

A current list of predefinitions is given in the cc(1) man page.

The __STDC__ identifier is predefined as an object-like macro as shown in the following table.

Table 4  Predefined Identifier __STDC__ on Oracle Solaris
Expands to:
When compiled with:
-Xc or -pedantic
-Xa,-Xt or -std without -pedantic flag
Not defined

On Oracle Linux the compiler predefines __STDC__ to expand to 1.

The compiler issues a warning if __STDC__ is undefined (#undef __STDC__). __STDC__ is not defined in –Xs mode.