尝试和抓住帕斯卡 [英] Try and Catch In Pascal

问题描述

我正在使用Dev-Pas 1.9.2，并尝试确保程序在输入符号或字母值时不会崩溃。

I'm using Dev-Pas 1.9.2 and am trying to make sure the program doesn't crash when a symbol or a letter value is entered.

我已经谷歌和谷歌搜索，找不到任何关于如何实现这一点的重新生效。

I've googled and googled and can't find any resoruce on how to achieve this.

任何帮助是非常感谢。谢谢！

Any help is greatly appreciated. Thanks!

以下是我要管理输入的代码：

Here is the code I'm trying to manage the input:

 Function GetMenuChoice : Integer;
  Var
    OptionChosen : Integer;
  Begin
    Write('Please enter your choice: ');
    Readln(OptionChosen);
    If (OptionChosen < 1) Or ((OptionChosen > 4) And (OptionChosen <> 9))
      Then
        Begin
          Writeln;
          Writeln('That was not one of the allowed options.  Please try again: ');
        End;
    GetMenuChoice := OptionChosen;
  End;

推荐答案

更改代码以接受Char;如果由于某种原因需要整数，请稍后处理转换。

Change your code to accept a Char instead; if you need an integer for some reason, handle the conversion afterward.

这在Delphi中有效;除非你不能使用像 ['1'..'4'，'9'] 这样的集合，并设置运算符，它应该可以正常工作。

This works in Delphi; unless you can't use sets like ['1'..'4','9'] and set operators, it should work fine.

Function GetMenuChoice : Char;
Var
  OptionChosen : Char;
Begin
  repeat
    Write('Please enter your choice: ');
    Readln(OptionChosen);

    If not (OptionChosen in ['1'..'4', '9'])
      Then
        Begin
          Writeln;
          Writeln('That was not one of the allowed options.  Please try again: ');
        End;
  until OptionChosen in ['1'..'4', '9'];
  GetMenuChoice := OptionChosen;
End;

如果您绝对需要一个要返回的数字，请将返回类型更改回整数（或字节）然后将最后一行更改为：

If you absolutely need a number to be returned, change the return type back to integer (or byte) and then change the final line to:

GetMenuChoice := Ord(OptionChosen) - 48;  

或

GetMenuChoice := Ord(OptionChosen) - Ord('0');

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