RosettaCodeData/Task/Reverse-a-string/True-BASIC/reverse-a-string.basic

FUNCTION reverse$(a$)
    LET b$ = ""
    FOR i = 1 TO LEN(a$)
        LET b$ = (a$)[i:i+1-1] & b$
    NEXT i
    LET reverse$ = b$
END FUNCTION

LET s$ = "asdf"
PRINT "'"; s$; "' reversed is '"; reverse$(s$); "'"
END