compiler-error-c2009.md

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Learn more about: Compiler Error C2009	Compiler Error C2009	11/04/2016	C2009	C2009	fe9d94ed-20a5-4d83-b9c4-60ee69d2f30a

Compiler Error C2009

reuse of macro formal 'identifier'

The formal parameter list of a macro definition uses the identifier more than once. Identifiers in the macro's parameter list must be unique.

Examples

The following sample generates C2009:

// C2009.cpp
#include <stdio.h>

#define macro1(a,a) (a*a)   // C2009

int main()
{
    printf_s("%d\n", macro1(2));
}

Possible resolution:

// C2009b.cpp
#include <stdio.h>

#define macro2(a)   (a*a)
#define macro3(a,b) (a*b)

int main()
{
    printf_s("%d\n", macro2(2));
    printf_s("%d\n", macro3(2,4));
}