how to #define strings

[MA WiSo]

i have a #define SIZE 32 that i change on compilation time as needed.

what i want to do is combine SIZE with strings in another #define
something like this:

#define FileName "In"+SIZE+".txt"
how can i do this right ??

[Peter87]

#define SIZE 32
#define STR_EXPAND(tok) #tok
#define STR(tok) STR_EXPAND(tok)
#define FileName "In" STR(SIZE) ".txt"