Sharp PC-1403 - Page 148

14 2
1 1 #1
The FOR and N E X T v erbs are u s ed in pair s to e n close a group of state m en t s w h ich a r e
to be r epea t ed . Th e fi rst time t h is gro u p o f statemen t s i s e x e c uted , the l oo p v ar i able
(the va riab l e named immedia t ely fo l lo win g t he FO R ) ha s the v al u e o f e x pre ss i on 1.
W h e n exec u t i on r ea c hes t he N EXT v erb, th e l oop variable is i n c r ea s ed by t he step s i ze
a n d then t h i s va l ue i s tested aga in st ex pre ss i on 2. If the v al u e of the l oop var i ab l e is
l ess than o r equa l to ex pressi o n 2 , t he enclos e d g r ou p o f statement s i s e x ec u ted
aga in , s tart i ng wi th the s t atem ent follow i ng t he FOR. In t h e f irst form , the step size i s
1 ; i n the sec o nd fo rm , the s t e p size i s given by ex p r essio n 3 . I f th e v alu e of the loop
varia bl e i s greate r tha n ex p ressi on 2 , execu t i on continues with t h e s t atement whic h
im media t e l y f o ll ows the N E X T . Bec ause t h e c om par i son i s m ade at t he end, the
statements with in a FOR / N EX T pa ir a re a lways execut e d at l e ast once .
E xp r e s s i on 1 , exp r es s io n 2, a nd expression 3 m u s t b e i n the r a n ge o f
-9 . 999999999E99 to 9.9 9 9999999 E 99 . If t h e value of e x p r ess i on 3 i s ze r o , F OR/
NEX T l o op w i ll be i nf i ni te .
T h e loo p va r ia b l e m ay b e u sed wi th i n the group of s t atem e n t s, f or examp l e , as an
i nd ex to an ar r ay , b ut care should be take n in c h a n gi n g t h e v alue of the l oop var ia b l e .
P rograms sho ul d be w r itten so t hat t hey n eve r ju m p fro m ou t s i de a F OR/NEXT p ai r t o a
sta t eme n t w i th in a F OR/N E X T pair . S i m ila rly, p r ograms mu s t n e v er l eave a F O R/
NEX T p a i r by jumping out. A l way s exit a F O R / N E X T l oo p via t h e N E X T s ta te ment. T o
do t hi s , set t h e l oop variab l e t o a val ue h i g h e r t h a n e x pr e ss i on 2 .
T he grou p o f stateme n ts enc l osed by a FOR /N E XT p air ca n i n c lu de anoth e r p a ir o f
FOR/N E XT s t atemen t s w hi c h use a di ff e r e n t loop varia bl e as lo ng as t he enc l osed pai r
i s c omp l e t e l y e ncl ose d ; i . e . , if a FO R state m e nt is inc l ude d in the gro up , t h e
match i ng NE X T m ust a l so b e i n c l uded . FOR/N E XT pai rs m a y b e " n ested " up t o five
le v el s deep.
•MUM·MM
T h e FO _ R ver b is u s e d in co mbin a tion wit h the N EX T ve r b to repeat a series of
ope r atio n s a spe ci fied number o f t i me s.
1 FOR n um er i c v a r ia bl e=express i o n 1 TO e x pressio n 2
2 FOR nu meric variable=expressio n 1 TO expr ess i o n 2
STEP e x p r ess i o n 3
Ab b reviatio n s : F . and F O . ; ST E .
See a l so : N E X T
V e r b s
FOR •• . TO