string delphi 如何将一个字符从字符串转换为字符
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How to convert one character from a string to a char in delphi
提问by Japster
I have a string, from which I want to extract one character that is needed to be used in a Casestatement. The thing is the Caseonly takes Charvalues and not string values. So how do I convert a single string character to a char?
我有一个字符串，我想从中提取一个需要在Case语句中使用的字符。事情是Case唯一的Char值而不是字符串值。那么如何将单个字符串字符转换为字符呢？
回答by Tony Hopkinson
Use the string as a character array (1-based), and use the index of the character you want to use in the casestatement. For instance, if you want to use the first character:
将字符串用作字符数组（从 1 开始），并使用要在case语句中使用的字符的索引。例如，如果您想使用第一个字符：
case MyString[1] Of
// ...
end;
NB make sure you check the the string is of at least that length before you use the subscript, or you'll get an access violation.
注意，在使用下标之前，请确保检查字符串的长度至少为该长度，否则会出现访问冲突。
回答by Jacek Krawczyk
Since stringbecame 0-based on mobile platforms, there is also an always-safe way to get a char from single-character string.
由于string在移动平台上成为 0-based ，还有一种始终安全的方法可以从单字符串中获取字符。
myString[Low(myString)]
回答by BitBumper
Since delphi became cross-platform I would use 0-based string access using TStringHelperclass out of unit System.SysUtils:
由于 delphi 成为跨平台，我将使用基于 0 的字符串访问，使用TStringHelperclass out of unit System.SysUtils：
case MyString.Chars(0) Of
// ...
end;
