blocks|key|898693|text|有很多方法，但这应该可以做到(虽然不知道它在处理非常大的字符串时是如何执行的)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|898694|private+static+string+GetNumbers(string+input)
{
++++return+new+string(input.Where(c+=>+char.IsDigit(c)).ToArray());
}|code-block|syntax|javascript|898695|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|$]]

There are many ways, but this should do (don't know how it performs with really large strings though):

<pre><code>private static string GetNumbers(string input)
{
 return new string(input.Where(c =&gt; char.IsDigit(c)).ToArray());
}
</code></pre>

blocks|key|898748|text|使用一个只捕获0-9的正则表达式，然后丢弃其余的。正则表达式是一种第一次会花费很多成本的操作。或者这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|898749|var+sb+=+new+StringBuilder();
var+goodChars+=+"0123456789".ToCharArray();
var+input+=+"40,595";
foreach(var+c+in+input)
{
++if(goodChars.IndexOf(c)+>=+0)
++++sb.Append(c);
}
var+output+=+sb.ToString();|code-block|syntax|javascript|898750|类似的东西我想，我还没有编译过..|898751|正如Fredrik所说，LINQ也是一种选择|898752|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Use either a regular expression that's only capturing 0-9 and throws away the rest. A regular expression is an operation that's going to cost a lot the first time though. Or do something like this:

<pre><code>var sb = new StringBuilder();
var goodChars = "0123456789".ToCharArray();
var input = "40,595";
foreach(var c in input)
{
 if(goodChars.IndexOf(c) &gt;= 0)
 sb.Append(c);
}
var output = sb.ToString();
</code></pre>

Something like that I think, I haven't compiled though..

LINQ is, as Fredrik said, also an option

blocks|key|1113522|text|嗯，你知道数字是什么:+0123456789，对吧？逐个字符地遍历字符串；如果字符是数字，则将其粘贴到临时字符串的末尾，否则忽略。对于C#字符串，可能还有其他帮助器方法可用，但这是一种通用方法，适用于任何地方。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1113523|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Well, you know what the digits are: 0123456789, right? Traverse your string character-by-character; if the character is a digit tack it onto the end of a temp string, otherwise ignore. There may be other helper methods available for C# strings but this is a generic approach that works everywhere.

blocks|key|898857|text|感觉很适合正则表达式。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|898858|var+s+=+"40,595+p.a.";
var+stripped+=+Regex.Replace(s,+"[%5E0-9]",+"");|code-block|syntax|javascript|898859|@"\D"可以取代"[%5E0-9]"，但我喜欢[%5E0-9]的可读性。|offset|length|style|CODE|898860|entityMap^0|0|0|0|5|9|8|M|6|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]|$I|T|J|U|K|L]|$I|V|J|W|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|X|8|@]|9|@]|A|$]]]|N|$]]

Feels like a good fit for a regular expression.

<pre><code>var s = "40,595 p.a.";
var stripped = Regex.Replace(s, "[^0-9]", "");
</code></pre>

<code>"[^0-9]"</code> can be replaced by <code>@"\D"</code> but I like the readability of <code>[^0-9]</code>.

blocks|key|1113636|text|下面是使用正则表达式的代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1113637|string+str+=+"40,595+p.a.";

StringBuilder+convert+=+new+StringBuilder();

string+pattern+=+@"\d%2B";
Regex+regex+=+new+Regex(pattern);

MatchCollection+matches+=+regex.Matches(str);

foreach+(Match+match+in+matches)
{
convert.Append(match.Groups[0].ToString());
}

int+value+=+Convert.ToInt32(convert.ToString());+|code-block|syntax|javascript|1113638|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|$]]

Here is the code using Regular Expressions:

<pre><code>string str = "40,595 p.a.";

StringBuilder convert = new StringBuilder();

string pattern = @"\d+";
Regex regex = new Regex(pattern);

MatchCollection matches = regex.Matches(str);

foreach (Match match in matches)
{
convert.Append(match.Groups[0].ToString());
}

int value = Convert.ToInt32(convert.ToString()); 
</code></pre>

blocks|key|898960|text|扩展方法将是更好的方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|898961|public+static+string+GetNumbers(this+string+text)
++++{
++++++++text+=+text+??+string.Empty;
++++++++return+new+string(text.Where(p+=>+char.IsDigit(p)).ToArray());
++++}|code-block|syntax|javascript|898962|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|$]]

An extension method will be a better approach:

<pre><code>public static string GetNumbers(this string text)
 {
 text = text ?? string.Empty;
 return new string(text.Where(p =&gt; char.IsDigit(p)).ToArray());
 }
</code></pre>

blocks|key|898986|text|另一个选择..。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|898987|private+static+string+RemoveNonNumberDigitsAndCharacters(string+text)
{
++++var+numericChars+=+"0123456789,.".ToCharArray();
++++return+new+String(text.Where(c+=>+numericChars.Any(n+=>+n+==+c)).ToArray());
}|code-block|syntax|javascript|898988|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|$]]

Another option ...

<pre><code>private static string RemoveNonNumberDigitsAndCharacters(string text)
{
 var numericChars = "0123456789,.".ToCharArray();
 return new String(text.Where(c =&gt; numericChars.Any(n =&gt; n == c)).ToArray());
}
</code></pre>

blocks|key|1113792|text|公认的答案很好，但是它没有考虑空值，因此在大多数情况下都是不可用的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1113793|这促使我转而使用这些辅助方法。第一个回答了操作，而其他的对于那些想要执行相反操作的人可能是有用的：|1113794|++++///+<summary>
++++///+Strips+out+non-numeric+characters+in+string,+returning+only+digits
++++///+ref.:+https://stackoverflow.com/questions/3977497/stripping-out-non-numeric-characters-in-string
++++///+</summary>
++++///+<param+name="input">the+input+string</param>
++++///+<param+name="throwExceptionIfNull">if+set+to+TRUE+it+will+throw+an+exception+if+the+input+string+is+null,+otherwise+it+will+return+null+as+well.</param>
++++///+<returns>the+input+string+numeric+part:+for+example,+if+input+is+"XYZ1234A5U6"+it+will+return+"123456"</returns>
++++public+static+string+GetNumbers(string+input,+bool+throwExceptionIfNull+=+false)
++++{
++++++++return+(input+==+null+&&+!throwExceptionIfNull)+
++++++++++++?+input+
++++++++++++:+new+string(input.Where(c+=>+char.IsDigit(c)).ToArray());
++++}

++++///+<summary>
++++///+Strips+out+numeric+and+special+characters+in+string,+returning+only+letters
++++///+</summary>
++++///+<param+name="input">the+input+string</param>
++++///+<param+name="throwExceptionIfNull">if+set+to+TRUE+it+will+throw+an+exception+if+the+input+string+is+null,+otherwise+it+will+return+null+as+well.</param>
++++///+<returns>the+letters+contained+within+the+input+string:+for+example,+if+input+is+"XYZ1234A5U6~()"+it+will+return+"XYZAU"</returns>
++++public+static+string+GetLetters(string+input,+bool+throwExceptionIfNull+=+false)
++++{
++++++++return+(input+==+null+&&+!throwExceptionIfNull)+
++++++++++++?+input+
++++++++++++:+new+string(input.Where(c+=>+char.IsLetter(c)).ToArray());
++++}

++++///+<summary>
++++///+Strips+out+any+non-numeric/non-digit+character+in+string,+returning+only+letters+and+numbers
++++///+</summary>
++++///+<param+name="input">the+input+string</param>
++++///+<param+name="throwExceptionIfNull">if+set+to+TRUE+it+will+throw+an+exception+if+the+input+string+is+null,+otherwise+it+will+return+null+as+well.</param>
++++///+<returns>the+letters+contained+within+the+input+string:+for+example,+if+input+is+"XYZ1234A5U6~()"+it+will+return+"XYZ1234A5U6"</returns>
++++public+static+string+GetLettersAndNumbers(string+input,+bool+throwExceptionIfNull+=+false)
++++{
++++++++return+(input+==+null+&&+!throwExceptionIfNull)+
++++++++++++?+input+
++++++++++++:+new+string(input.Where(c+=>+char.IsLetterOrDigit(c)).ToArray());
++++}|code-block|syntax|javascript|1113795|有关更多信息，请访问我的博客上的read+this+post。|offset|length|1113796|entityMap|0|LINK|mutability|MUTABLE|url|http://www.ryadel.com/en/strip-numeric-digit-letter-characters-string-asp-net-c-sharp/^0|0|0|0|G|E|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|W|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|X|8|@]|9|@$K|Y|L|Z|1|10]]|A|$]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T]]]]

The accepted answer is great, however it doesn't take NULL values into account, thus making it unusable in most scenarios.

This drove me into using these helper methods instead. The first one answers the OP, while the others may be useful for those who want to perform the opposite:

<pre><code> /// &lt;summary&gt;
 /// Strips out non-numeric characters in string, returning only digits
 /// ref.: https://stackoverflow.com/questions/3977497/stripping-out-non-numeric-characters-in-string
 /// &lt;/summary&gt;
 /// &lt;param name="input"&gt;the input string&lt;/param&gt;
 /// &lt;param name="throwExceptionIfNull"&gt;if set to TRUE it will throw an exception if the input string is null, otherwise it will return null as well.&lt;/param&gt;
 /// &lt;returns&gt;the input string numeric part: for example, if input is "XYZ1234A5U6" it will return "123456"&lt;/returns&gt;
 public static string GetNumbers(string input, bool throwExceptionIfNull = false)
 {
 return (input == null &amp;&amp; !throwExceptionIfNull) 
 ? input 
 : new string(input.Where(c =&gt; char.IsDigit(c)).ToArray());
 }

 /// &lt;summary&gt;
 /// Strips out numeric and special characters in string, returning only letters
 /// &lt;/summary&gt;
 /// &lt;param name="input"&gt;the input string&lt;/param&gt;
 /// &lt;param name="throwExceptionIfNull"&gt;if set to TRUE it will throw an exception if the input string is null, otherwise it will return null as well.&lt;/param&gt;
 /// &lt;returns&gt;the letters contained within the input string: for example, if input is "XYZ1234A5U6~()" it will return "XYZAU"&lt;/returns&gt;
 public static string GetLetters(string input, bool throwExceptionIfNull = false)
 {
 return (input == null &amp;&amp; !throwExceptionIfNull) 
 ? input 
 : new string(input.Where(c =&gt; char.IsLetter(c)).ToArray());
 }

 /// &lt;summary&gt;
 /// Strips out any non-numeric/non-digit character in string, returning only letters and numbers
 /// &lt;/summary&gt;
 /// &lt;param name="input"&gt;the input string&lt;/param&gt;
 /// &lt;param name="throwExceptionIfNull"&gt;if set to TRUE it will throw an exception if the input string is null, otherwise it will return null as well.&lt;/param&gt;
 /// &lt;returns&gt;the letters contained within the input string: for example, if input is "XYZ1234A5U6~()" it will return "XYZ1234A5U6"&lt;/returns&gt;
 public static string GetLettersAndNumbers(string input, bool throwExceptionIfNull = false)
 {
 return (input == null &amp;&amp; !throwExceptionIfNull) 
 ? input 
 : new string(input.Where(c =&gt; char.IsLetterOrDigit(c)).ToArray());
 }
</code></pre>

For additional info, <a href="http://www.ryadel.com/en/strip-numeric-digit-letter-characters-string-asp-net-c-sharp/" rel="nofollow noreferrer">read this post</a> on my blog.

blocks|key|1113816|text|+var+output+=+new+string(input.Where(char.IsNumber).ToArray());|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1113817|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> var output = new string(input.Where(char.IsNumber).ToArray());
</code></pre>

blocks|key|1113826|text|public+static+string+RemoveNonNumeric(string+value)+=>+Regex.Replace(value,+"[%5E0-9]",+"");|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1113827|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 string RemoveNonNumeric(string value) =&gt; Regex.Replace(value, "[^0-9]", "");
</code></pre>

blocks|key|899190|text|如果你在VB中工作，并最终来到这里，".Where“会为我抛出一个错误。从这里得到这个：https://forums.asp.net/t/1067058.aspx?Trimming%2Ba%2Bstring%2Bto%2Bremove%2Bspecial%2Bnon%2Bnumeric%2Bcharacters|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|899191|Function+ParseDigits(ByVal+inputString+as+String)+As+String
++Dim+numberString+As+String+=+""
++If+inputString+=+Nothing+Then+Return+numberString

++For+Each+c+As+Char+In+inputString.ToCharArray()
++++If+c.IsDigit+Then
++++++numberString+&=+c
++++End+If
++Next+c

++Return+numberString
End+Function|code-block|syntax|javascript|899192|entityMap|0|LINK|mutability|MUTABLE|url|https://forums.asp.net/t/1067058.aspx?Trimming%2Ba%2Bstring%2Bto%2Bremove%2Bspecial%2Bnon%2Bnumeric%2Bcharacters^0|18|2O|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

If you're working in VB and ended up here, the &quot;.Where&quot; threw an error for me. Got this from here: <a href="https://forums.asp.net/t/1067058.aspx?Trimming+a+string+to+remove+special+non+numeric+characters" rel="nofollow noreferrer">https://forums.asp.net/t/1067058.aspx?Trimming+a+string+to+remove+special+non+numeric+characters</a>
<pre><code>Function ParseDigits(ByVal inputString as String) As String
 Dim numberString As String = &quot;&quot;
 If inputString = Nothing Then Return numberString

 For Each c As Char In inputString.ToCharArray()
 If c.IsDigit Then
 numberString &amp;= c
 End If
 Next c

 Return numberString
End Function
</code></pre>

I'm looking to strip out non-numeric characters in a string in ASP.NET C#, i.e. <code>40,595 p.a.</code> would end up as <code>40595</code>.
Thanks

Stripping out non-numeric characters in string

我希望在ASP.NET C#中剔除字符串中的非数字字符，即40,595 p.a.将以40595结尾。谢谢

问剔除字符串中的非数字字符
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