I have a Csound instrument that triggers a new sound every 30 seconds with random parameters. So, a new sound every time.

I would like each sound to be recorded in a different sound file, such as file1.wav, file2.wav, etc.
I tried to increment an integer value and concat this value with a string :

ifile = ifile + 1

Sfile1 strcat "file", ifile

Sfile1 strcat Sfile1, ".wav"

but strcat accepts strings only…
How can I achieve that ?