Pat Bohrer wrote:
> #define CONCAT4(a,b,c,d) (a##b##c##d)
>
> main()
> {
> CONCAT4(A,B,C,D)
> CONCAT4(A_A,B_B,C_C,D_D)
> CONCAT4(0_1,1_2,3_4,5_6)
>
> }
> main ( )
> {
> ( ABCD )
> ( A_AB_BC_CD_D )
> ( 0 _11 _23 _45 _6 )
>
> }
0_1 is not a valid preprocessing token, because it starts with
a numeral. It actually is two pp tokens, namely 0 and _1 .
Segher
