"#if" with no condition

[tomy]

Hi Group:
The confusing code is as below:
//-------------------------------------------------
#if
#define FOO foo
#else
#define FOO foobar
#endif
//-------------------------------------------------

Could the "#if" be with no following expression? However, the code
can't be compiled (gcc). Does any new C stardard defne THIS new method
about "#if"? Or it just equal to #if 0 ??

--tomy

 

[Robert Gamble]

Hi Group:
The confusing code is as below:
//-------------------------------------------------
#if
#define FOO foo
#else
#define FOO foobar
#endif
//-------------------------------------------------

Could the "#if" be with no following expression? However, the code
can't be compiled (gcc). Does any new C stardard defne THIS new method
about "#if"? Or it just equal to #if 0 ??

An #if directive requires a constant expression, your example is not
valid C.

Robert Gamble