Difference between revisions of "If/zh CN"
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<delphi> | <delphi> | ||
if condition | if condition | ||
− | then | + | then statement1; |
else statement2; | else statement2; | ||
</delphi> | </delphi> | ||
Line 25: | Line 25: | ||
<delphi> | <delphi> | ||
if condition1 | if condition1 | ||
− | then if condition2 then | + | then if condition2 then statement1; |
else statement2; | else statement2; | ||
</delphi> | </delphi> | ||
Line 38: | Line 38: | ||
if condition | if condition | ||
then begin | then begin | ||
− | if condition2 then | + | if condition2 then statement1; |
end | end | ||
else statement2; | else statement2; |
Revision as of 06:29, 5 December 2010
If then(条件语句)
<delphi>
if condition then statement1 else statement2;
</delphi>
Condition 是布尔表达式
如果 Condition 为真则执行 statement1,否则执行 statement2。
Else 和 statement2 可省略,此时如 Condition 为假则跳过 if 语句。
注意:1. else 之前不能加分号。下面是不合法的:
<delphi>
if condition then statement1; else statement2;
</delphi>
2.else 总是与和它最近的if配对:
<delphi>
if condition1 then if condition2 then statement1; else statement2;
</delphi>
上面的else与第二个if配对;
要使else与第一个if配对,则应写成这样:
<delphi>
if condition then begin if condition2 then statement1; end else statement2;
</delphi>
If语句中使用复合语句
If语句可以使用复合语句 (begin ... end Block)。
<delphi>
if boolean_condition then begin statement1; statement2; statement3; end;
</delphi>
Keywords: begin — do — else — end — for — if — repeat — then — until — while