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Basic Pascal Tutorial/Chapter 3/WHILE..DO/zh CN: what changed

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

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1+3Db - WHILE..DO循环 (原作者: Tao Yue, 状态: 未更改)
2+
3+先判断后循环：
4+
5+``` pascal
6+while 逻辑表达式 do
7+ 语句;
8+```
9+
10+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。
11+
12+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：
13+
14+``` pascal
15+a := 5;
16+while a < 6 do
17+ writeln (a);
18+```
19+
20+通过改变变量，以避免循环：
21+
22+``` pascal
23+a := 5;
24+while a < 6 do
25+begin
26+ writeln (a);
27+ a := a + 1
28+end;
29+```
30+
31+`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。
32+
33+| | | |
34+|----|----|----|
35+| [[Basic Pascal Tutorial/Chapter 3/FOR..DO/zh CN|上一页]] | [[Basic Pascal Tutorial/Contents/zh CN|目录]] | [[Basic Pascal Tutorial/Chapter 3/REPEAT..UNTIL/zh CN|下一页]] |
36+
37+---
38+*From the Free Pascal wiki, page "Basic Pascal Tutorial/Chapter 3/WHILE..DO/zh CN", as it stood on 2022-08-20 after a change by Kai Burghardt, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).*

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