blocks|key|1867868|text|试试这个：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1867869|//+using+System.CodeDom.Compiler;
CodeDomProvider+provider+=+CodeDomProvider.CreateProvider("C#");
if+(provider.IsValidIdentifier+(YOUR_VARIABLE_NAME))+{
++++++//+Valid
}+else+{
++++++//+Not+valid
}|code-block|syntax|javascript|1867870|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Try this:

<pre><code>// using System.CodeDom.Compiler;
CodeDomProvider provider = CodeDomProvider.CreateProvider("C#");
if (provider.IsValidIdentifier (YOUR_VARIABLE_NAME)) {
 // Valid
} else {
 // Not valid
}
</code></pre>

blocks|key|2010252|text|在@字符周围有几种很容易忘记检查的特殊情况-即'@'本身不是有效的标识符，"@1foo"也不是。要捕获这些字符，可以首先检查字符串是否为关键字，然后删除字符串开头的@，然后检查剩余部分是否为有效的标识符(不允许使用@字符)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2010253|在这里，我将其与解析标识符中的Unicode转义序列的方法结合起来，希望能够完成C#+(5.0)+Unicode字符检查。要使用它，首先调用TryParseRawIdentifier()来处理关键字、转义序列、格式化字符(已删除)和逐字标识符。接下来，将结果传递给IsValidParsedIdentifier()以检查第一个字符和后续字符是否有效。请注意，当且仅当标识符被C#视为相同时，从TryParseRawIdentifier()返回的字符串才相等。|2010254|public+static+class+CSharpIdentifiers
{
++++private+static+HashSet<string>+_keywords+=+new+HashSet<string>+{
++++++++"abstract",+"as",+"base",+"bool",+"break",+"byte",+"case",+"catch",+"char",+"checked",
++++++++"class",+"const",+"continue",+"decimal",+"default",+"delegate",+"do",+"double",+"else",
++++++++"enum",+"event",+"explicit",+"extern",+"false",+"finally",+"fixed",+"float",+"for",
++++++++"foreach",+"goto",+"if",+"implicit",+"in",+"int",+"interface",+"internal",+"is",+"lock",
++++++++"long",+"namespace",+"new",+"null",+"object",+"operator",+"out",+"override",+"params",
++++++++"private",+"protected",+"public",+"readonly",+"ref",+"return",+"sbyte",+"sealed",
++++++++"short",+"sizeof",+"stackalloc",+"static",+"string",+"struct",+"switch",+"this",+"throw",
++++++++"true",+"try",+"typeof",+"uint",+"ulong",+"unchecked",+"unsafe",+"ushort",+"using",
++++++++"virtual",+"void",+"volatile",+"while"
++++};

++++public+static+IReadOnlyCollection<string>+Keywords+{+get+{+return+_keywords;+}+}


++++public+static+bool+TryParseRawIdentifier(string+str,+out+string+parsed)
++++{
++++++++if+(string.IsNullOrEmpty(str)+%7C%7C+_keywords.Contains(str))+{+parsed+=+null;+return+false;+}

++++++++StringBuilder+sb+=+new+StringBuilder(str.Length);

++++++++int+verbatimCharWidth+=+str[0]+==+'@'+?+1+:+0;

++++++++for+(int+i+=+verbatimCharWidth;+i+<+str.Length;+)+//Manual+increment
++++++++{
++++++++++++char+c+=+str[i];

++++++++++++if+(c+==+'\\')
++++++++++++{
++++++++++++++++char+next+=+str[i+%2B+1];

++++++++++++++++int+charCodeLength;
++++++++++++++++if+(next+==+'u')+charCodeLength+=+4;
++++++++++++++++else+if+(next+==+'U')+charCodeLength+=+8;
++++++++++++++++else+{+parsed+=+null;+return+false;+}
++++++++++++++++//No+need+to+check+for+escaped+backslashes+or+special+sequences+like+\n,
++++++++++++++++//as+they+not+valid+identifier+characters

++++++++++++++++int+charCode;
++++++++++++++++if+(!TryParseHex(str.Substring(i+%2B+2,+charCodeLength),+out+charCode))+{+parsed+=+null;+return+false;+}

++++++++++++++++sb.Append(char.ConvertFromUtf32(charCodeLength));+//Handle+characters+above+2%5E16+by+converting+them+to+a+surrogate+pair
++++++++++++++++i+%2B=+2+%2B+charCodeLength;
++++++++++++}
++++++++++++else+if+(char.GetUnicodeCategory(str,+i)+==+UnicodeCategory.Format)
++++++++++++{
++++++++++++++++//Use+(string,+index)+in+order+to+handle+surrogate+pairs
++++++++++++++++//Skip+this+character
++++++++++++++++if+(char.IsSurrogatePair(str,+i))+i+%2B=+2;
++++++++++++++++else+i+%2B=+1;
++++++++++++}
++++++++++++else
++++++++++++{
++++++++++++++++sb.Append(c);
++++++++++++++++i%2B%2B;
++++++++++++}
++++++++}

++++++++parsed+=+sb.ToString();
++++++++return+true;
++++}

++++private+static+bool+TryParseHex(string+str,+out+int+result)
++++{
++++++++return+int.TryParse(str,+NumberStyles.AllowHexSpecifier,+CultureInfo.InvariantCulture,+out+result);
++++++++//NumberStyles.AllowHexSpecifier+forces+all+characters+to+be+hex+digits
++++}

++++public+static+bool+IsValidParsedIdentifier(string+str)
++++{
++++++++if+(string.IsNullOrEmpty(str))+return+false;

++++++++if+(!IsValidParsedIdentifierStart(str,+0))+return+false;

++++++++int+firstCharWidth+=+char.IsSurrogatePair(str,+0)+?+2+:+1;

++++++++for+(int+i+=+firstCharWidth;+i+<+str.Length;+)+//Manual+increment
++++++++{
++++++++++++if+(!IsValidParsedIdentifierPart(str,+i))+return+false;
++++++++++++if+(char.IsSurrogatePair(str,+i))+i+%2B=+2;
++++++++++++else+i+%2B=+1;
++++++++}

++++++++return+true;
++++}

++++//(String,+index)+pairs+are+used+instead+of+chars+in+order+to+support+surrogate+pairs
++++//(Unicode+code-points+above+2%5E16+represented+using+two+16-bit+characters)

++++public+static+bool+IsValidParsedIdentifierStart(string+s,+int+index)
++++{
++++++++return+s[index]+==+'_'+%7C%7C+char.IsLetter(s,+index)+%7C%7C+char.GetUnicodeCategory(s,+index)+==+UnicodeCategory.LetterNumber;
++++}

++++public+static+bool+IsValidParsedIdentifierPart(string+s,+int+index)
++++{
++++++++if+(s[index]+==+'_'+%7C%7C+(s[index]+>=+'0'+&&+s[index]+<=+'9')+%7C%7C+char.IsLetter(s,+index))+return+true;

++++++++switch+(char.GetUnicodeCategory(s,+index))
++++++++{
++++++++++++case+UnicodeCategory.LetterNumber:+//Eg.+Special+Roman+numeral+characters+(not+covered+by+IsLetter())
++++++++++++case+UnicodeCategory.DecimalDigitNumber:+//Includes+decimal+digits+in+other+cultures
++++++++++++case+UnicodeCategory.ConnectorPunctuation:
++++++++++++case+UnicodeCategory.NonSpacingMark:
++++++++++++case+UnicodeCategory.SpacingCombiningMark:
++++++++++++//UnicodeCategory.Format+handled+in+TryParseRawIdentifier()
++++++++++++++++return+true;
++++++++++++default:
++++++++++++++++return+false;
++++++++}
++++}
}|code-block|syntax|javascript|2010255|entityMap^0|1|1|N|3|11|7|2A|1|2Z|1|0|1Y|N|3O|P|5G|N|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]|$9|T|A|U|B|C]|$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Z|8|@$9|10|A|11|B|C]|$9|12|A|13|B|C]|$9|14|A|15|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|16|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|17|8|@]|D|@]|E|$]]]|N|$]]

There are a couple of special cases around the <code>@</code> character that are easy to forget to check - namely, <code>'@'</code> by itself is not a valid identifier, and neither is <code>"@1foo"</code>. To catch these, you can first check if the string is a keyword, then remove <code>@</code> from the start of the string, and then check if what's left is a valid identifier (disallowing <code>@</code> characters).

Here I've combined this with a method to parse Unicode escape sequences in identifiers, and hopefully complete C# (5.0) Unicode character checking. To use it, first call <code>TryParseRawIdentifier()</code> to handle keywords, escape sequences, formatting characters (which are removed), and verbatim identifiers. Next, pass the result to <code>IsValidParsedIdentifier()</code> to check if the first and subsequent characters are valid. Note that the strings returned from <code>TryParseRawIdentifier()</code> are equal if and only if the identifiers are considered identical by C#.

<pre><code>public static class CSharpIdentifiers
{
 private static HashSet&lt;string&gt; _keywords = new HashSet&lt;string&gt; {
 "abstract", "as", "base", "bool", "break", "byte", "case", "catch", "char", "checked",
 "class", "const", "continue", "decimal", "default", "delegate", "do", "double", "else",
 "enum", "event", "explicit", "extern", "false", "finally", "fixed", "float", "for",
 "foreach", "goto", "if", "implicit", "in", "int", "interface", "internal", "is", "lock",
 "long", "namespace", "new", "null", "object", "operator", "out", "override", "params",
 "private", "protected", "public", "readonly", "ref", "return", "sbyte", "sealed",
 "short", "sizeof", "stackalloc", "static", "string", "struct", "switch", "this", "throw",
 "true", "try", "typeof", "uint", "ulong", "unchecked", "unsafe", "ushort", "using",
 "virtual", "void", "volatile", "while"
 };

 public static IReadOnlyCollection&lt;string&gt; Keywords { get { return _keywords; } }


 public static bool TryParseRawIdentifier(string str, out string parsed)
 {
 if (string.IsNullOrEmpty(str) || _keywords.Contains(str)) { parsed = null; return false; }

 StringBuilder sb = new StringBuilder(str.Length);

 int verbatimCharWidth = str[0] == '@' ? 1 : 0;

 for (int i = verbatimCharWidth; i &lt; str.Length; ) //Manual increment
 {
 char c = str[i];

 if (c == '\\')
 {
 char next = str[i + 1];

 int charCodeLength;
 if (next == 'u') charCodeLength = 4;
 else if (next == 'U') charCodeLength = 8;
 else { parsed = null; return false; }
 //No need to check for escaped backslashes or special sequences like \n,
 //as they not valid identifier characters

 int charCode;
 if (!TryParseHex(str.Substring(i + 2, charCodeLength), out charCode)) { parsed = null; return false; }

 sb.Append(char.ConvertFromUtf32(charCodeLength)); //Handle characters above 2^16 by converting them to a surrogate pair
 i += 2 + charCodeLength;
 }
 else if (char.GetUnicodeCategory(str, i) == UnicodeCategory.Format)
 {
 //Use (string, index) in order to handle surrogate pairs
 //Skip this character
 if (char.IsSurrogatePair(str, i)) i += 2;
 else i += 1;
 }
 else
 {
 sb.Append(c);
 i++;
 }
 }

 parsed = sb.ToString();
 return true;
 }

 private static bool TryParseHex(string str, out int result)
 {
 return int.TryParse(str, NumberStyles.AllowHexSpecifier, CultureInfo.InvariantCulture, out result);
 //NumberStyles.AllowHexSpecifier forces all characters to be hex digits
 }

 public static bool IsValidParsedIdentifier(string str)
 {
 if (string.IsNullOrEmpty(str)) return false;

 if (!IsValidParsedIdentifierStart(str, 0)) return false;

 int firstCharWidth = char.IsSurrogatePair(str, 0) ? 2 : 1;

 for (int i = firstCharWidth; i &lt; str.Length; ) //Manual increment
 {
 if (!IsValidParsedIdentifierPart(str, i)) return false;
 if (char.IsSurrogatePair(str, i)) i += 2;
 else i += 1;
 }

 return true;
 }

 //(String, index) pairs are used instead of chars in order to support surrogate pairs
 //(Unicode code-points above 2^16 represented using two 16-bit characters)

 public static bool IsValidParsedIdentifierStart(string s, int index)
 {
 return s[index] == '_' || char.IsLetter(s, index) || char.GetUnicodeCategory(s, index) == UnicodeCategory.LetterNumber;
 }

 public static bool IsValidParsedIdentifierPart(string s, int index)
 {
 if (s[index] == '_' || (s[index] &gt;= '0' &amp;&amp; s[index] &lt;= '9') || char.IsLetter(s, index)) return true;

 switch (char.GetUnicodeCategory(s, index))
 {
 case UnicodeCategory.LetterNumber: //Eg. Special Roman numeral characters (not covered by IsLetter())
 case UnicodeCategory.DecimalDigitNumber: //Includes decimal digits in other cultures
 case UnicodeCategory.ConnectorPunctuation:
 case UnicodeCategory.NonSpacingMark:
 case UnicodeCategory.SpacingCombiningMark:
 //UnicodeCategory.Format handled in TryParseRawIdentifier()
 return true;
 default:
 return false;
 }
 }
}
</code></pre>

blocks|key|2010273|text|++public+static+bool+IsIdentifier(string+text)
++{
+++++if+(string.IsNullOrEmpty(text))
++++++++return+false;
+++++if+(!char.IsLetter(text[0])+&&+text[0]+!=+'_')
++++++++return+false;
+++++for+(int+ix+=+1;+ix+<+text.Length;+%2B%2Bix)
++++++++if+(!char.IsLetterOrDigit(text[ix])+&&+text[ix]+!=+'_')
+++++++++++return+false;
+++++return+true;
++}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|2010274|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code> public static bool IsIdentifier(string text)
 {
 if (string.IsNullOrEmpty(text))
 return false;
 if (!char.IsLetter(text[0]) &amp;&amp; text[0] != '_')
 return false;
 for (int ix = 1; ix &lt; text.Length; ++ix)
 if (!char.IsLetterOrDigit(text[ix]) &amp;&amp; text[ix] != '_')
 return false;
 return true;
 }
</code></pre>

blocks|key|2010292|text|在WPF中，这可用于检查字符串是否为有效的变量名。但它不会重新识别"public“这样的保留字符串。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|2010293|//+works+only+in+WPF!
public+static+bool+CheckIfStringIsValidVarName(string+stringToCheck)
{
++++if+(string.IsNullOrWhiteSpace(stringToCheck))
++++++++return+false;

++++TextBox+textBox+=+new+TextBox();

++++try
++++{
++++++++//+stringToCheck+==+"";+//+!!!+does+NOT+throw+!!!
++++++++//+stringToCheck+==+"Name$";+//+throws
++++++++//+stringToCheck+==+"0";+//+throws
++++++++//+stringToCheck+==+"name+with+blank";+//+throws
++++++++//+stringToCheck+==+"public";+//+does+NOT+throw
++++++++//+stringToCheck+==+"ValidName";

++++++++textBox.Name+=+stringToCheck;
++++}
++++catch+(ArgumentException+ex)
++++{
++++++++return+false;
++++}

++++return+true;
}|code-block|syntax|javascript|2010294|entityMap^0|1|3|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

In WPF this can be uses to check if a string is a valid variable name. But it does not regognize reserved strings like "public".

<pre><code>// works only in WPF!
public static bool CheckIfStringIsValidVarName(string stringToCheck)
{
 if (string.IsNullOrWhiteSpace(stringToCheck))
 return false;

 TextBox textBox = new TextBox();

 try
 {
 // stringToCheck == ""; // !!! does NOT throw !!!
 // stringToCheck == "Name$"; // throws
 // stringToCheck == "0"; // throws
 // stringToCheck == "name with blank"; // throws
 // stringToCheck == "public"; // does NOT throw
 // stringToCheck == "ValidName";

 textBox.Name = stringToCheck;
 }
 catch (ArgumentException ex)
 {
 return false;
 }

 return true;
}
</code></pre>

I'm looking for a quick way (in C#) to determine if a string is a valid variable name. My first intuition is to whip up some regex to do it, but I'm wondering if there's a better way to do it. Like maybe some kind of a secret method hidden deep somewhere called IsThisAValidVariableName(string name), or some other slick way to do it that is not prone to errors that might arise due to lack of regex prowess.

How to determine if a string is a valid variable name?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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社区新版编辑器体验调研

我正在寻找一种快速的方法(在C#中)来确定一个字符串是否是有效的变量名。我的第一个直觉是创建一些正则表达式来做这件事，但我想知道是否有更好的方法。比如某种隐藏在某个地方的秘密方法，称为IsThisAValidVariableName(字符串名)，或者其他一些巧妙的方法，它不容易因为缺乏正则表达式能力而出现错误。

问如何确定字符串是否为有效的变量名？
EN

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问如何确定字符串是否为有效的变量名？
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