c - Use #define from macro -

c - Use #define from macro -

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how concatenate twice c preprocessor , expand macro in “arg ## _ ## macro”? 2 answers

i have #defined preprocessor constant called currentclass. macro method reads constant build method declaration current class.

#define currentclass foo #define method(x) \ currentclass ## _ ## x void method(bar)() { }

the preprocessor produces next result:

void currentclass_bar() { }

obviously, currentclass_bar here should foo_bar. next on other hand produces right result.

#define method(class, x) \ class ## _ ## x void method(foo, bar)() { }

for reason, method can't concatenate constant currentclass else. currentclass lone produces desired foo string.

any thought happening here?

you have expand twice

#define xx(x0,x1) x0 ## _ ## x1 #define x(x0,x1) xx(x0,x1) #define method(y) \ x(currentclass,y)

c c-preprocessor