ARRAYWRITE lenght

Hi,
I need to know how much chars is in array, when using ARRAYWRITE.
Looking at pbppic18.lib I manage somehow to get length.

Code:

---

ARRAYWRITE FAT_src,[] : FAT_count = R5
 ARRAYWRITE FAT_src,["some text to test"]
 FAT_count = R5-FAT_count
 serout2 pc_tx,Baud_Rate,[13,10,"FAT_count:", DEC FAT_count,13,10]

---

Is there better way to do this?