我希望在 ASP.NET C# 中删除字符串中的非数字字符，即
40,595 p.a.40595有很多方法，但这应该可以（虽然不知道它如何处理非常大的字符串）：
private static string GetNumbers(string input)
{
return new string(input.Where(c => char.IsDigit(c)).ToArray());
}
感觉很适合正则表达式。
var s = "40,595 p.a.";
var stripped = Regex.Replace(s, "[^0-9]", "");
"[^0-9]"@"\D"[^0-9]扩展方法将是更好的方法：
public static string GetNumbers(this string text)
{
text = text ?? string.Empty;
return new string(text.Where(p => char.IsDigit(p)).ToArray());
}
public static string RemoveNonNumeric(string value) => Regex.Replace(value, "[^0-9]", "");
另一种选择...
private static string RemoveNonNumberDigitsAndCharacters(string text)
{
var numericChars = "0123456789,.".ToCharArray();
return new String(text.Where(c => numericChars.Any(n => n == c)).ToArray());
}
使用仅捕获 0-9 并丢弃其余部分的正则表达式。不过，正则表达式是一种第一次会花费大量成本的操作。或者做这样的事情：
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();
我想是这样的，但我还没有编译..
正如 Fredrik 所说，LINQ 也是一种选择
var output = new string(input.Where(char.IsNumber).ToArray());
从 C# 3.0 开始，您应该尽可能使用方法组代替 lambda 表达式。这是因为使用方法组会减少一次重定向，因此效率更高。
当前接受的答案将变为：
private static string GetNumbers(string input)
{
return new string(input.Where(char.IsDigit).ToArray());
}
嗯，你知道这些数字是什么：0123456789，对吧？逐个字符地遍历字符串；如果字符是数字，则将其附加到临时字符串的末尾，否则忽略。 可能还有其他可用于 C# 字符串的辅助方法，但这是一种适用于任何地方的通用方法。
这是使用正则表达式的代码：
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());
接受的答案很好，但是它没有考虑 NULL 值，因此在大多数情况下无法使用。
这促使我转而使用这些辅助方法。第一个回答了OP，而其他人可能对那些想要执行相反操作的人有用：
/// <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());
}
如需了解更多信息，请阅读我博客上的这篇文章。
如果您在 VB 中工作并最终来到这里，那么“.Where”会给我带来错误。从这里得到这个：https://forums.asp.net/t/1067058.aspx?Trimming+a+string+to+remove+special+non+numeric+characters
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
删除所有非数字字符
Public Function OnlyNumeric(strIn As String) As String
Try
Return Regex.Replace(strIn, "[^0-9]", "")
Catch
Return String.Empty
End Try
End Function