Difference between revisions of "Basic Pascal Tutorial/Chapter 4/Forward Referencing/zh CN"
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4F - 前向引用 (原作者: Tao Yue, 状态: 未更改) | 4F - 前向引用 (原作者: Tao Yue, 状态: 未更改) | ||
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− | |[[Contents/ | + | |[[Basic Pascal Tutorial/Contents/zh CN|目录]] |
− | |[[ | + | |[[Basic Pascal Tutorial/Chapter 4/Programming Assignment/zh_CN|下一页]] |
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Latest revision as of 16:20, 20 August 2022
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4F - 前向引用 (原作者: Tao Yue, 状态: 未更改)
这些虽然容易理解,但有时也让人困惑。
程序中只能使用已经定义的过程/函数?或许是这样吧,先定义后使用。
不过,也有例外,你想先使用后定义?要解决这类问题,你需要使用前向引用。(在预先声明的过程/函数后加forward)
如:
procedure Later (参数列表); forward;
procedure Sooner (参数列表);
begin
...
Later (参数列表);
end;
...
procedure Later;
begin
...
Sooner (参数列表);
end;
示例:
program q;
procedure a;forward;
procedure b;
begin
writeln('B调取A:');
a;
end;
procedure a;
begin
writeln('A过程.');
end;
begin
b;
end.
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