Basic Pascal Tutorial/Chapter 3/WHILE..DO/zh CN

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3Db - WHILE..DO循环 (原作者: Tao Yue, 状态: 未更改)

先判断后循环:

while 逻辑表达式 do
  语句;

判断逻辑表达式为真,则继续执行循环;直至表达式为假将退出循环。

在循环体中你必须设法改变表达式的值(即,造成为假的条件),否则,它将是一个死循环:

a := 5;
while a < 6 do
  writeln (a);


通过改变变量,以避免循环:

a := 5;
while a < 6 do
begin
  writeln (a);
  a := a + 1
end;

WHILE...DO 称之为先判断后循环,即,在进入循环前,先判断条件是否为真,如果为假,将不会进入循环。

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