174  Pascal Report  9.2.3.1.  While  statement.  Repetitil'eStatement  =  WhileStaten 'lit  I  RepeatStatement  I  ForStatement .  WhileStatement  =  "while"  Booft IIIFxpression  "do"  Statement.  The statement is repeatedly e.\ecuted until the expression becomes  false,  If  its value is false at the  be~  inning, the statement is not executed  at all. The while statement  while B do  S  is equivalent to (unless S  contain~  u  labelled statement):  if B then begin S;  w:  i  le B do  Send  Examples of while statements:  while GrayScale[1]  <  while  I  >  0  do  begin  10  I  ,- succ(1)  if odd (I)  then Y:  Y  *  X;  I  ,- I  di  v  2;  X  := sqr(X)  end  while not  eof(F)  do bE  Jin  p(Fi);  Get(F)  end  9.2.3.2.  Repeat statements.  RepeatStatement  = "repeat"  Stal, '111£'lltSequence  "unt i I"  B{)(,ic(/llE.rpression.  The statement sequence is rep,'utcdly executed (and at least once)  until the expression becomes true  The repeat statement  repeat  S  until B  is equivalent to  begin  S;  if not B  tl  r  repeat  S  until Bend  unless S  contains a labelled state \lent.  Examples of repeat statements:  repeat  K ,- I  mod J;  repeat  P  (Fi);  Get(F)  until eof (F)  ,- J;  J  ,- K  until J  o 