从c#字符串中删除字符
本文关键字：删除 字符 字符串 | 更新日期: 2023-09-27 18:08:36
如何从字符串中删除字符?例如:"My name @is ,Wan.;'; Wan" .
我想从该字符串中删除字符'@', ',', '.', ';', ''''，使其成为"My name is Wan Wan"
var str = "My name @is ,Wan.;'; Wan";
var charsToRemove = new string[] { "@", ",", ".", ";", "'" };
foreach (var c in charsToRemove)
{
str = str.Replace(c, string.Empty);
}
但如果你想删除所有非字母字符
，我可能会建议另一种方法var str = "My name @is ,Wan.;'; Wan";
str = new string((from c in str
where char.IsWhiteSpace(c) || char.IsLetterOrDigit(c)
select c
).ToArray());
Simple:
String.Join("", "My name @is ,Wan.;'; Wan".Split('@', ',' ,'.' ,';', ''''));
听起来像是RegEx的理想应用程序——一个为快速文本处理而设计的引擎。在本例中:
Regex.Replace("He'"ll,o Wo'r.ld", "[@,''.'";''''']", string.Empty)
比较各种建议(以及在目标的不同大小和位置的单字符替换情况下的比较)。
在这个特殊的情况下，分割目标和连接替换(在这个情况下，空字符串)是最快的至少3倍。最终，性能取决于替换的数量、替换在源中的位置以及源的大小。# ymmv
结果(全部结果在这里)
| Test | Compare | Elapsed |
|---------------------------|---------|--------------------------------------------------------------------|
| SplitJoin | 1.00x | 29023 ticks elapsed (2.9023 ms) [in 10K reps, 0.00029023 ms per] |
| Replace | 2.77x | 80295 ticks elapsed (8.0295 ms) [in 10K reps, 0.00080295 ms per] |
| RegexCompiled | 5.27x | 152869 ticks elapsed (15.2869 ms) [in 10K reps, 0.00152869 ms per] |
| LinqSplit | 5.43x | 157580 ticks elapsed (15.758 ms) [in 10K reps, 0.0015758 ms per] |
| Regex, Uncompiled | 5.85x | 169667 ticks elapsed (16.9667 ms) [in 10K reps, 0.00169667 ms per] |
| Regex | 6.81x | 197551 ticks elapsed (19.7551 ms) [in 10K reps, 0.00197551 ms per] |
| RegexCompiled Insensitive | 7.33x | 212789 ticks elapsed (21.2789 ms) [in 10K reps, 0.00212789 ms per] |
| Regex Insensitive | 7.52x | 218164 ticks elapsed (21.8164 ms) [in 10K reps, 0.00218164 ms per] |
测试套件(LinqPad)
(注意:Perf和Vs是我写的计时扩展)
void test(string title, string sample, string target, string replacement) {
var targets = target.ToCharArray();
var tox = "[" + target + "]";
var x = new Regex(tox);
var xc = new Regex(tox, RegexOptions.Compiled);
var xci = new Regex(tox, RegexOptions.Compiled | RegexOptions.IgnoreCase);
// no, don't dump the results
var p = new Perf/*<string>*/();
p.Add(string.Join(" ", title, "Replace"), n => targets.Aggregate(sample, (res, curr) => res.Replace(new string(curr, 1), replacement)));
p.Add(string.Join(" ", title, "SplitJoin"), n => String.Join(replacement, sample.Split(targets)));
p.Add(string.Join(" ", title, "LinqSplit"), n => String.Concat(sample.Select(c => targets.Contains(c) ? replacement : new string(c, 1))));
p.Add(string.Join(" ", title, "Regex"), n => Regex.Replace(sample, tox, replacement));
p.Add(string.Join(" ", title, "Regex Insentive"), n => Regex.Replace(sample, tox, replacement, RegexOptions.IgnoreCase));
p.Add(string.Join(" ", title, "Regex, Uncompiled"), n => x.Replace(sample, replacement));
p.Add(string.Join(" ", title, "RegexCompiled"), n => xc.Replace(sample, replacement));
p.Add(string.Join(" ", title, "RegexCompiled Insensitive"), n => xci.Replace(sample, replacement));
var trunc = 40;
var header = sample.Length > trunc ? sample.Substring(0, trunc) + "..." : sample;
p.Vs(header);
}
void Main()
{
// also see https://stackoverflow.com/questions/7411438/remove-characters-from-c-sharp-string
"Control".Perf(n => { var s = "*"; });
var text = "My name @is ,Wan.;'; Wan";
var clean = new[] { '@', ',', '.', ';', '''' };
test("stackoverflow", text, string.Concat(clean), string.Empty);
var target = "o";
var f = "x";
var replacement = "1";
var fillers = new Dictionary<string, string> {
{ "short", new String(f[0], 10) },
{ "med", new String(f[0], 300) },
{ "long", new String(f[0], 1000) },
{ "huge", new String(f[0], 10000) }
};
var formats = new Dictionary<string, string> {
{ "start", "{0}{1}{1}" },
{ "middle", "{1}{0}{1}" },
{ "end", "{1}{1}{0}" }
};
foreach(var filler in fillers)
foreach(var format in formats) {
var title = string.Join("-", filler.Key, format.Key);
var sample = string.Format(format.Value, target, filler.Value);
test(title, sample, target, replacement);
}
}
对于您的问题不太具体，可以通过在正则表达式中列出可接受的字符来删除字符串中的所有标点符号(空格除外):
string dirty = "My name @is ,Wan.;'; Wan";
// only space, capital A-Z, lowercase a-z, and digits 0-9 are allowed in the string
string clean = Regex.Replace(dirty, "[^A-Za-z0-9 ]", "");
请注意，9之后有一个空格，以免从句子中删除空格。第三个参数是一个空字符串，用于替换不属于正则表达式的任何子字符串。
string x = "My name @is ,Wan.;'; Wan";
string modifiedString = x.Replace("@", "").Replace(",", "").Replace(".", "").Replace(";", "").Replace("'", "");
最简单的方法是使用String.Replace:
String s = string.Replace("StringToReplace", "NewString");
这是我编写的一个方法，它采用了稍微不同的方法。我没有指定要删除的字符，而是告诉我的方法我想保留哪些字符——它将删除所有其他字符。
在OP的例子中，他只想保留字母字符和空格。下面是对我的方法的调用(c# demo):
var str = "My name @is ,Wan.;'; Wan";
// "My name is Wan Wan"
var result = RemoveExcept(str, alphas: true, spaces: true);
/// <summary>
/// Returns a copy of the original string containing only the set of whitelisted characters.
/// </summary>
/// <param name="value">The string that will be copied and scrubbed.</param>
/// <param name="alphas">If true, all alphabetical characters (a-zA-Z) will be preserved; otherwise, they will be removed.</param>
/// <param name="numerics">If true, all numeric characters (0-9) will be preserved; otherwise, they will be removed.</param>
/// <param name="dashes">If true, all dash characters (-) will be preserved; otherwise, they will be removed.</param>
/// <param name="underlines">If true, all underscore characters (_) will be preserved; otherwise, they will be removed.</param>
/// <param name="spaces">If true, all whitespace (e.g. spaces, tabs) will be preserved; otherwise, they will be removed.</param>
/// <param name="periods">If true, all dot characters (".") will be preserved; otherwise, they will be removed.</param>
public static string RemoveExcept(string value, bool alphas = false, bool numerics = false, bool dashes = false, bool underlines = false, bool spaces = false, bool periods = false) {
if (string.IsNullOrWhiteSpace(value)) return value;
if (new[] { alphas, numerics, dashes, underlines, spaces, periods }.All(x => x == false)) return value;
var whitelistChars = new HashSet<char>(string.Concat(
alphas ? "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" : "",
numerics ? "0123456789" : "",
dashes ? "-" : "",
underlines ? "_" : "",
periods ? "." : "",
spaces ? " " : ""
).ToCharArray());
var scrubbedValue = value.Aggregate(new StringBuilder(), (sb, @char) => {
if (whitelistChars.Contains(@char)) sb.Append(@char);
return sb;
}).ToString();
return scrubbedValue;
}
以@drzaus的性能数据为例，这里是一个使用最快算法的扩展方法。
public static class StringEx
{
public static string RemoveCharacters(this string s, params char[] unwantedCharacters)
=> s == null ? null : string.Join(string.Empty, s.Split(unwantedCharacters));
}
var name = "edward woodward!";
var removeDs = name.RemoveCharacters('d', '!');
Assert.Equal("ewar woowar", removeDs); // old joke
另一个简单的解决方案:
var forbiddenChars = @"@,.;'".ToCharArray();
var dirty = "My name @is ,Wan.;'; Wan";
var clean = new string(dirty.Where(c => !forbiddenChars.Contains(c)).ToArray());
new List<string> { "@", ",", ".", ";", "'" }.ForEach(m => str = str.Replace(m, ""));
字符串只是一个字符数组，所以使用Linq来做替换(类似于上面的Albin，除了使用Linq包含语句来做替换):
var resultString = new string(
(from ch in "My name @is ,Wan.;'; Wan"
where ! @"@,.;''".Contains(ch)
select ch).ToArray());
第一个字符串是替换和中的字符的字符串第二个是一个简单的字符串，包含字符
我不妨把它扔到这里。
创建一个扩展以从字符串中删除字符:
public static string RemoveChars(this string input, params char[] chars)
{
var sb = new StringBuilder();
for (int i = 0; i < input.Length; i++)
{
if (!chars.Contains(input[i]))
sb.Append(input[i]);
}
return sb.ToString();
}
它可以这样使用:
string str = "My name @is ,Wan.;'; Wan";
string cleanedUpString = str.RemoveChars('@', ',', '.', ';', '''');
或者像这样:
string str = "My name @is ,Wan.;'; Wan".RemoveChars('@', ',', '.', ';', '''');
似乎最短的方法是将LINQ和string.Concat结合起来:
var input = @"My name @is ,Wan.;'; Wan";
var chrs = new[] {'@', ',', '.', ';', ''''};
var result = string.Concat(input.Where(c => !chrs.Contains(c)));
// => result = "My name is Wan Wan"
参见c#演示。注意，string.Concat是string.Join("", ...)的快捷方式。
请注意，使用regex删除单个已知字符仍然可以动态构建，尽管人们认为regex速度较慢。然而，这里有一种方法来构建这样一个动态正则表达式(你所需要的只是一个字符类):
var pattern = $"[{Regex.Escape(new string(chrs))}]+";
var result = Regex.Replace(input, pattern, string.Empty);
参见另一个c#演示。regex将看起来像[@,'.;']+(匹配一个或多个(+)连续出现的@, ,, ., ;或'字符)，其中点不必转义，但Regex.Escape将必要转义其他必须转义的字符，如', ^, ]或-，其在字符类中的位置您无法预测。
下面是一个删除文件名中无效字符的好方法:
string.Join(string.Empty, filename.Split(System.IO.Path.GetInvalidFileNameChars()));
这里有很多好的答案，这是我的补充以及几个可以用来帮助测试正确性的单元测试，我的解决方案类似于@Rianne的上面，但使用isset来提供O(1)查找时间在替换字符(也类似于@Albin Sunnanbo的Linq解决方案)。
using System;
using System.Collections.Generic;
using System.Linq;
/// <summary>
/// Returns a string with the specified characters removed.
/// </summary>
/// <param name="source">The string to filter.</param>
/// <param name="removeCharacters">The characters to remove.</param>
/// <returns>A new <see cref="System.String"/> with the specified characters removed.</returns>
public static string Remove(this string source, IEnumerable<char> removeCharacters)
{
if (source == null)
{
throw new ArgumentNullException("source");
}
if (removeCharacters == null)
{
throw new ArgumentNullException("removeCharacters");
}
// First see if we were given a collection that supports ISet
ISet<char> replaceChars = removeCharacters as ISet<char>;
if (replaceChars == null)
{
replaceChars = new HashSet<char>(removeCharacters);
}
IEnumerable<char> filtered = source.Where(currentChar => !replaceChars.Contains(currentChar));
return new string(filtered.ToArray());
}
这里有NUnit(2.6+)测试
using System;
using System.Collections;
using System.Collections.Generic;
using NUnit.Framework;
[TestFixture]
public class StringExtensionMethodsTests
{
[TestCaseSource(typeof(StringExtensionMethodsTests_Remove_Tests))]
public void Remove(string targetString, IEnumerable<char> removeCharacters, string expected)
{
string actual = StringExtensionMethods.Remove(targetString, removeCharacters);
Assert.That(actual, Is.EqualTo(expected));
}
[TestCaseSource(typeof(StringExtensionMethodsTests_Remove_ParameterValidation_Tests))]
public void Remove_ParameterValidation(string targetString, IEnumerable<char> removeCharacters)
{
Assert.Throws<ArgumentNullException>(() => StringExtensionMethods.Remove(targetString, removeCharacters));
}
}
internal class StringExtensionMethodsTests_Remove_Tests : IEnumerable
{
public IEnumerator GetEnumerator()
{
yield return new TestCaseData("My name @is ,Wan.;'; Wan", new char[] { '@', ',', '.', ';', '''' }, "My name is Wan Wan").SetName("StringUsingCharArray");
yield return new TestCaseData("My name @is ,Wan.;'; Wan", new HashSet<char> { '@', ',', '.', ';', '''' }, "My name is Wan Wan").SetName("StringUsingISetCollection");
yield return new TestCaseData(string.Empty, new char[1], string.Empty).SetName("EmptyStringNoReplacementCharactersYieldsEmptyString");
yield return new TestCaseData(string.Empty, new char[] { 'A', 'B', 'C' }, string.Empty).SetName("EmptyStringReplacementCharsYieldsEmptyString");
yield return new TestCaseData("No replacement characters", new char[1], "No replacement characters").SetName("StringNoReplacementCharactersYieldsString");
yield return new TestCaseData("No characters will be replaced", new char[] { 'Z' }, "No characters will be replaced").SetName("StringNonExistantReplacementCharactersYieldsString");
yield return new TestCaseData("AaBbCc", new char[] { 'a', 'C' }, "ABbc").SetName("CaseSensitivityReplacements");
yield return new TestCaseData("ABC", new char[] { 'A', 'B', 'C' }, string.Empty).SetName("AllCharactersRemoved");
yield return new TestCaseData("AABBBBBBCC", new char[] { 'A', 'B', 'C' }, string.Empty).SetName("AllCharactersRemovedMultiple");
yield return new TestCaseData("Test That They Didn't Attempt To Use .Except() which returns distinct characters", new char[] { '(', ')' }, "Test That They Didn't Attempt To Use .Except which returns distinct characters").SetName("ValidateTheStringIsNotJustDistinctCharacters");
}
}
internal class StringExtensionMethodsTests_Remove_ParameterValidation_Tests : IEnumerable
{
public IEnumerator GetEnumerator()
{
yield return new TestCaseData(null, null);
yield return new TestCaseData("valid string", null);
yield return new TestCaseData(null, new char[1]);
}
}
这是我通常在相同情况下使用的一个强大的方法:
private string Normalize(string text)
{
return string.Join("",
from ch in text
where char.IsLetterOrDigit(ch) || char.IsWhiteSpace(ch)
select ch);
}
享受……
旧校本复制/stomp:
private static string RemoveDirtyCharsFromString(string in_string)
{
int index = 0;
int removed = 0;
byte[] in_array = Encoding.UTF8.GetBytes(in_string);
foreach (byte element in in_array)
{
if ((element == ' ') ||
(element == '-') ||
(element == ':'))
{
removed++;
}
else
{
in_array[index] = element;
index++;
}
}
Array.Resize<byte>(ref in_array, (in_array.Length - removed));
return(System.Text.Encoding.UTF8.GetString(in_array, 0, in_array.Length));
}
不确定其他方法的效率(即在c#执行中作为副作用发生的所有函数调用和实例化的开销)。
我把它扩展方法和字符串数组，我认为string[]比char[]更有用，因为char也可以是字符串:
public static class Helper
{
public static string RemoverStrs(this string str, string[] removeStrs)
{
foreach (var removeStr in removeStrs)
str = str.Replace(removeStr, "");
return str;
}
}
那么你可以在任何地方使用它:
string myname = "My name @is ,Wan.;'; Wan";
string result = myname.RemoveStrs(new[]{ "@", ",", ".", ";", "''"});
我需要从XML文件中删除特殊字符。我是这样做的。char.ToString()是代码中的英雄。
string item = "<item type="line" />"
char DC4 = (char)0x14;
string fixed = item.Replace(DC4.ToString(), string.Empty);
new[] { ',', '.', ';', '''', '@' }
.Aggregate("My name @is ,Wan.;'; Wan", (s, c) => s.Replace(c.ToString(), string.Empty));
如果您想删除所有的空格和特殊字符
var input = Console.ReadLine();
foreach (var item in input)
{
var limit = ((int)item);
if (limit>=65 && limit<=90 || limit>=97 && limit<= 122)
{
Console.Write(item);
}
}