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: 1 -Xc or -pedantic 0 -Xa,-Xt or -std without -pedantic flag Not defined -Xs

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.