when you talk about loop....a loop is meant to traverse multiple entries....for example in a table...we can loop on rows...
what exactly do you mean by looping on a string array (As such there are no arrays in ABAP).
if you have multiple strings, you can put each string in an internal table and then loop through this internal table using the LOOP AT....ENDLOOP statements.
in case of a single string, you can traverse it using offsets
eg : STR+0(10) ---> which means start from position 0 and read 10 characters.
please clarify a bit more on your requirement.