Difference between revisions of "Basic Pascal Tutorial/Chapter 4/Forward Referencing/zh CN"

From Free Pascal wiki
Jump to navigationJump to search
m (Fixed syntax highlighting; deleted category included in page template)
m (bypass language bar/categorization template redirect [cf. discussion])
 
(3 intermediate revisions by the same user not shown)
Line 1: Line 1:
{{Forward Referencing}}
+
{{Basic Pascal Tutorial/Chapter 4/Forward Referencing}}
  
 
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)
Line 53: Line 53:
  
 
{|style=color-backgroud="white" cellspacing="20"
 
{|style=color-backgroud="white" cellspacing="20"
|[[Recursion/zh_CN|上一页]]
+
|[[Basic Pascal Tutorial/Chapter 4/Recursion/zh_CN|上一页]]
|[[Contents/zh_CN|目录]]
+
|[[Basic Pascal Tutorial/Contents/zh CN|目录]]
|[[Programming_Assignment_4/zh_CN|下一页]]
+
|[[Basic Pascal Tutorial/Chapter 4/Programming Assignment/zh_CN|下一页]]
 
|}
 
|}

Latest revision as of 15:20, 20 August 2022

български (bg) English (en) français (fr) 日本語 (ja) 中文(中国大陆)‎ (zh_CN)

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.

相关

维基百科前向声明

上一页 目录 下一页