比方说，我有一个字符串，例如：
"Hello how are you doing?"
我想，轮流多个空格转换为一个空间的函数。
所以，我会得到：
"Hello how are you doing?"
我知道我可以使用正则表达式或致电
string s = "Hello how are you doing?".replace(" "," ");
但是，我不得不多次调用它，以确保所有的连续空格都只有一个替代。
有没有已经为这个内置的方法？
string cleanedString = System.Text.RegularExpressions.Regex.Replace(dirtyString,@"\s+"," ");
这个问题不是那么简单，其他海报做出来的人（和我最初认为它是） - 因为这个问题是不是很精确，因为它必须这样做。
有“空间”和“空白”之间的差异。 如果你仅仅意味着空格，那么你应该使用的正则表达式" {2,}" 。 如果你的意思是任何空白，这是一个不同的问题。 如果所有的空格转换为空格？ 应该发生什么变化，在开始和结束空间？
对于下面的标杆，我认为你只在乎空间，你不想做任何单一的空间，即使是在开始和结束。
需要注意的是正确性几乎总是比性能更重要。 该拆分/加入溶液中的事实，删除任何前导/尾随空格（甚至只是一个空格）是不正确的，至于你规定的要求（这可能是不完整的，当然）。
基准采用MiniBench 。
using System;
using System.Text.RegularExpressions;
using MiniBench;
internal class Program
{
public static void Main(string[] args)
{
int size = int.Parse(args[0]);
int gapBetweenExtraSpaces = int.Parse(args[1]);
char[] chars = new char[size];
for (int i=0; i < size/2; i += 2)
{
// Make sure there actually *is* something to do
chars[i*2] = (i % gapBetweenExtraSpaces == 1) ? ' ' : 'x';
chars[i*2 + 1] = ' ';
}
// Just to make sure we don't have a \0 at the end
// for odd sizes
chars[chars.Length-1] = 'y';
string bigString = new string(chars);
// Assume that one form works :)
string normalized = NormalizeWithSplitAndJoin(bigString);
var suite = new TestSuite<string, string>("Normalize")
.Plus(NormalizeWithSplitAndJoin)
.Plus(NormalizeWithRegex)
.RunTests(bigString, normalized);
suite.Display(ResultColumns.All, suite.FindBest());
}
private static readonly Regex MultipleSpaces =
new Regex(@" {2,}", RegexOptions.Compiled);
static string NormalizeWithRegex(string input)
{
return MultipleSpaces.Replace(input, " ");
}
// Guessing as the post doesn't specify what to use
private static readonly char[] Whitespace =
new char[] { ' ' };
static string NormalizeWithSplitAndJoin(string input)
{
string[] split = input.Split
(Whitespace, StringSplitOptions.RemoveEmptyEntries);
return string.Join(" ", split);
}
}
一些测试运行：
c:\Users\Jon\Test>test 1000 50
============ Normalize ============
NormalizeWithSplitAndJoin 1159091 0:30.258 22.93
NormalizeWithRegex 26378882 0:30.025 1.00
c:\Users\Jon\Test>test 1000 5
============ Normalize ============
NormalizeWithSplitAndJoin 947540 0:30.013 1.07
NormalizeWithRegex 1003862 0:29.610 1.00
c:\Users\Jon\Test>test 1000 1001
============ Normalize ============
NormalizeWithSplitAndJoin 1156299 0:29.898 21.99
NormalizeWithRegex 23243802 0:27.335 1.00
在这里，第一个数字是迭代次数，第二个是所花费的时间，和第三个是一个比例分数1.0为最佳。
这表明，至少在某些情况下（包括本）正则表达式可以超越分流/加入溶液，有时由非常显著余量。
但是，如果您更改为“所有空白”的要求，然后拆分/加入确实出现取胜。 正如通常的情况一样，魔鬼在细节...
虽然现有的答案都很好，我想指出一个方法不工作：
public static string DontUseThisToCollapseSpaces(string text)
{
while (text.IndexOf(" ") != -1)
{
text = text.Replace(" ", " ");
}
return text;
}
这可以永远循环下去。 有人在乎猜为什么？ （我只碰到这个来了，当它在几年前问作为一个新闻组的问题......有人居然跑成其为一个问题。）
定期expressoin将是最简单的方法。 如果你写的正则表达式正确的方法，你不会需要多个呼叫。
它改成这样：
string s = System.Text.RegularExpressions.Regex.Replace(s, @"\s{2,}", " ");
正如所指出的，这是很容易用正则表达式来完成。 我就补充一点，你可能要添加一个.trim（）到要摆脱前/后的空白。
这是我的工作与解决方案。 如果没有正则表达式和String.Split。
public static string TrimWhiteSpace(this string Value)
{
StringBuilder sbOut = new StringBuilder();
if (!string.IsNullOrEmpty(Value))
{
bool IsWhiteSpace = false;
for (int i = 0; i < Value.Length; i++)
{
if (char.IsWhiteSpace(Value[i])) //Comparion with WhiteSpace
{
if (!IsWhiteSpace) //Comparison with previous Char
{
sbOut.Append(Value[i]);
IsWhiteSpace = true;
}
}
else
{
IsWhiteSpace = false;
sbOut.Append(Value[i]);
}
}
}
return sbOut.ToString();
}
所以你可以：
string cleanedString = dirtyString.TrimWhiteSpace();
我分享我所用，因为它显示我拿出不同的东西。 我一直在使用这一段时间，这是对我来说足够快。 我不知道它如何对别人。 我用它在分隔的文件作家，在通过它一次运行大型数据表一个字段。
public static string NormalizeWhiteSpace(string S)
{
string s = S.Trim();
bool iswhite = false;
int iwhite;
int sLength = s.Length;
StringBuilder sb = new StringBuilder(sLength);
foreach(char c in s.ToCharArray())
{
if(Char.IsWhiteSpace(c))
{
if (iswhite)
{
//Continuing whitespace ignore it.
continue;
}
else
{
//New WhiteSpace
//Replace whitespace with a single space.
sb.Append(" ");
//Set iswhite to True and any following whitespace will be ignored
iswhite = true;
}
}
else
{
sb.Append(c.ToString());
//reset iswhitespace to false
iswhite = false;
}
}
return sb.ToString();
}
使用测试程序，乔恩斯基特贴出来，我想看看我是否能得到一个手写的循环运行速度更快。
我可以击败NormalizeWithSplitAndJoin每一次，但只有1000个，5个输入击败NormalizeWithRegex。
static string NormalizeWithLoop(string input)
{
StringBuilder output = new StringBuilder(input.Length);
char lastChar = '*'; // anything other then space
for (int i = 0; i < input.Length; i++)
{
char thisChar = input[i];
if (!(lastChar == ' ' && thisChar == ' '))
output.Append(thisChar);
lastChar = thisChar;
}
return output.ToString();
}
我没有看过的机器代码的抖动产生，但是，我希望这个问题是由呼叫采取StringBuilder.Append（）和做得更好就需要使用不安全代码的时间。
所以Regex.Replace（）是非常快，很难被击败！
快速多余的空格卸妆...这是最快的国家之一，并且基于费利佩·马查多的就地副本。
static string InPlaceCharArray(string str)
{
var len = str.Length;
var src = str.ToCharArray();
int dstIdx = 0;
bool lastWasWS = false;
for (int i = 0; i < len; i++)
{
var ch = src[i];
if (src[i] == '\u0020')
{
if (lastWasWS == false)
{
src[dstIdx++] = ch;
lastWasWS = true;
}
}
else
{
lastWasWS = false;
src[dstIdx++] = ch;
}
}
return new string(src, 0, dstIdx);
}
该基准测试...
InPlaceCharArraySpaceOnly由菲利普马查多在CodeProject 2015和由Sunsetquest用于多空间去除改性。 时间：3.75蜱
InPlaceCharArray由菲利普马查多 2015和稍微Sunsetquest用于多空间去除改性。 时间6.50蜱 （支持标签也）
通过SplitAndJoinOnSpace 乔恩斯基特 。 时间：13.25蜱
StringBuilder的由伏波 时间：13.5蜱 （支持标签也）
由编译正则表达式乔恩斯基特 。 时间：17蜱
StringBuilder的由戴维家 2013 时间：30.5蜱
正则表达式与非编译布兰登 时间：63.25蜱
StringBuilder的由user214147 时间：77.125蜱
正则表达式与非编译添Hoolihan 时间：147.25蜱
该基准测试代码...
using System;
using System.Text.RegularExpressions;
using System.Diagnostics;
using System.Threading;
using System.Text;
static class Program
{
public static void Main(string[] args)
{
long seed = ConfigProgramForBenchmarking();
Stopwatch sw = new Stopwatch();
string warmup = "This is a Warm up function for best benchmark results." + seed;
string input1 = "Hello World, how are you doing?" + seed;
string input2 = "It\twas\t \tso nice to\t\t see you \tin 1950. \t" + seed;
string correctOutput1 = "Hello World, how are you doing?" + seed;
string correctOutput2 = "It\twas\tso nice to\tsee you in 1950. " + seed;
string output1,output2;
//warm-up timer function
sw.Restart();
sw.Stop();
sw.Restart();
sw.Stop();
long baseVal = sw.ElapsedTicks;
// InPlace Replace by Felipe Machado but modified by Ryan for multi-space removal (http://www.codeproject.com/Articles/1014073/Fastest-method-to-remove-all-whitespace-from-Strin)
output1 = InPlaceCharArraySpaceOnly (warmup);
sw.Restart();
output1 = InPlaceCharArraySpaceOnly (input1);
output2 = InPlaceCharArraySpaceOnly (input2);
sw.Stop();
Console.WriteLine("InPlaceCharArraySpaceOnly : " + (sw.ElapsedTicks - baseVal));
Console.WriteLine(" Trial1:(spaces only) " + (output1 == correctOutput1 ? "PASS " : "FAIL "));
Console.WriteLine(" Trial2:(spaces+tabs) " + (output2 == correctOutput2 ? "PASS " : "FAIL "));
// InPlace Replace by Felipe R. Machado and slightly modified by Ryan for multi-space removal (http://www.codeproject.com/Articles/1014073/Fastest-method-to-remove-all-whitespace-from-Strin)
output1 = InPlaceCharArray(warmup);
sw.Restart();
output1 = InPlaceCharArray(input1);
output2 = InPlaceCharArray(input2);
sw.Stop();
Console.WriteLine("InPlaceCharArray: " + (sw.ElapsedTicks - baseVal));
Console.WriteLine(" Trial1:(spaces only) " + (output1 == correctOutput1 ? "PASS " : "FAIL "));
Console.WriteLine(" Trial2:(spaces+tabs) " + (output2 == correctOutput2 ? "PASS " : "FAIL "));
//Regex with non-compile Tim Hoolihan (https://stackoverflow.com/a/1279874/2352507)
string cleanedString =
output1 = Regex.Replace(warmup, @"\s+", " ");
sw.Restart();
output1 = Regex.Replace(input1, @"\s+", " ");
output2 = Regex.Replace(input2, @"\s+", " ");
sw.Stop();
Console.WriteLine("Regex by Tim Hoolihan: " + (sw.ElapsedTicks - baseVal));
Console.WriteLine(" Trial1:(spaces only) " + (output1 == correctOutput1 ? "PASS " : "FAIL "));
Console.WriteLine(" Trial2:(spaces+tabs) " + (output2 == correctOutput2 ? "PASS " : "FAIL "));
//Regex with compile by Jon Skeet (https://stackoverflow.com/a/1280227/2352507)
output1 = MultipleSpaces.Replace(warmup, " ");
sw.Restart();
output1 = MultipleSpaces.Replace(input1, " ");
output2 = MultipleSpaces.Replace(input2, " ");
sw.Stop();
Console.WriteLine("Regex with compile by Jon Skeet: " + (sw.ElapsedTicks - baseVal));
Console.WriteLine(" Trial1:(spaces only) " + (output1 == correctOutput1 ? "PASS " : "FAIL "));
Console.WriteLine(" Trial2:(spaces+tabs) " + (output2 == correctOutput2 ? "PASS " : "FAIL "));
//Split And Join by Jon Skeet (https://stackoverflow.com/a/1280227/2352507)
output1 = SplitAndJoinOnSpace(warmup);
sw.Restart();
output1 = SplitAndJoinOnSpace(input1);
output2 = SplitAndJoinOnSpace(input2);
sw.Stop();
Console.WriteLine("Split And Join by Jon Skeet: " + (sw.ElapsedTicks - baseVal));
Console.WriteLine(" Trial1:(spaces only) " + (output1 == correctOutput1 ? "PASS " : "FAIL "));
Console.WriteLine(" Trial2:(spaces+tabs) " + (output2 == correctOutput2 ? "PASS " : "FAIL "));
//Regex by Brandon (https://stackoverflow.com/a/1279878/2352507
output1 = Regex.Replace(warmup, @"\s{2,}", " ");
sw.Restart();
output1 = Regex.Replace(input1, @"\s{2,}", " ");
output2 = Regex.Replace(input2, @"\s{2,}", " ");
sw.Stop();
Console.WriteLine("Regex by Brandon: " + (sw.ElapsedTicks - baseVal));
Console.WriteLine(" Trial1:(spaces only) " + (output1 == correctOutput1 ? "PASS " : "FAIL "));
Console.WriteLine(" Trial2:(spaces+tabs) " + (output2 == correctOutput2 ? "PASS " : "FAIL "));
//StringBuilder by user214147 (https://stackoverflow.com/a/2156660/2352507
output1 = user214147(warmup);
sw.Restart();
output1 = user214147(input1);
output2 = user214147(input2);
sw.Stop();
Console.WriteLine("StringBuilder by user214147: " + (sw.ElapsedTicks - baseVal));
Console.WriteLine(" Trial1:(spaces only) " + (output1 == correctOutput1 ? "PASS " : "FAIL "));
Console.WriteLine(" Trial2:(spaces+tabs) " + (output2 == correctOutput2 ? "PASS " : "FAIL "));
//StringBuilder by fubo (https://stackoverflow.com/a/27502353/2352507
output1 = fubo(warmup);
sw.Restart();
output1 = fubo(input1);
output2 = fubo(input2);
sw.Stop();
Console.WriteLine("StringBuilder by fubo: " + (sw.ElapsedTicks - baseVal));
Console.WriteLine(" Trial1:(spaces only) " + (output1 == correctOutput1 ? "PASS " : "FAIL "));
Console.WriteLine(" Trial2:(spaces+tabs) " + (output2 == correctOutput2 ? "PASS " : "FAIL "));
//StringBuilder by David S 2013 (https://stackoverflow.com/a/16035044/2352507)
output1 = SingleSpacedTrim(warmup);
sw.Restart();
output1 = SingleSpacedTrim(input1);
output2 = SingleSpacedTrim(input2);
sw.Stop();
Console.WriteLine("StringBuilder(SingleSpacedTrim) by David S: " + (sw.ElapsedTicks - baseVal));
Console.WriteLine(" Trial1:(spaces only) " + (output1 == correctOutput1 ? "PASS " : "FAIL "));
Console.WriteLine(" Trial2:(spaces+tabs) " + (output2 == correctOutput2 ? "PASS " : "FAIL "));
}
// InPlace Replace by Felipe Machado and slightly modified by Ryan for multi-space removal (http://www.codeproject.com/Articles/1014073/Fastest-method-to-remove-all-whitespace-from-Strin)
static string InPlaceCharArray(string str)
{
var len = str.Length;
var src = str.ToCharArray();
int dstIdx = 0;
bool lastWasWS = false;
for (int i = 0; i < len; i++)
{
var ch = src[i];
if (src[i] == '\u0020')
{
if (lastWasWS == false)
{
src[dstIdx++] = ch;
lastWasWS = true;
}
}
else
{
lastWasWS = false;
src[dstIdx++] = ch;
}
}
return new string(src, 0, dstIdx);
}
// InPlace Replace by Felipe R. Machado but modified by Ryan for multi-space removal (http://www.codeproject.com/Articles/1014073/Fastest-method-to-remove-all-whitespace-from-Strin)
static string InPlaceCharArraySpaceOnly (string str)
{
var len = str.Length;
var src = str.ToCharArray();
int dstIdx = 0;
bool lastWasWS = false; //Added line
for (int i = 0; i < len; i++)
{
var ch = src[i];
switch (ch)
{
case '\u0020': //SPACE
case '\u00A0': //NO-BREAK SPACE
case '\u1680': //OGHAM SPACE MARK
case '\u2000': // EN QUAD
case '\u2001': //EM QUAD
case '\u2002': //EN SPACE
case '\u2003': //EM SPACE
case '\u2004': //THREE-PER-EM SPACE
case '\u2005': //FOUR-PER-EM SPACE
case '\u2006': //SIX-PER-EM SPACE
case '\u2007': //FIGURE SPACE
case '\u2008': //PUNCTUATION SPACE
case '\u2009': //THIN SPACE
case '\u200A': //HAIR SPACE
case '\u202F': //NARROW NO-BREAK SPACE
case '\u205F': //MEDIUM MATHEMATICAL SPACE
case '\u3000': //IDEOGRAPHIC SPACE
case '\u2028': //LINE SEPARATOR
case '\u2029': //PARAGRAPH SEPARATOR
case '\u0009': //[ASCII Tab]
case '\u000A': //[ASCII Line Feed]
case '\u000B': //[ASCII Vertical Tab]
case '\u000C': //[ASCII Form Feed]
case '\u000D': //[ASCII Carriage Return]
case '\u0085': //NEXT LINE
if (lastWasWS == false) //Added line
{
src[dstIdx++] = ch; //Added line
lastWasWS = true; //Added line
}
continue;
default:
lastWasWS = false; //Added line
src[dstIdx++] = ch;
break;
}
}
return new string(src, 0, dstIdx);
}
static readonly Regex MultipleSpaces =
new Regex(@" {2,}", RegexOptions.Compiled);
//Split And Join by Jon Skeet (https://stackoverflow.com/a/1280227/2352507)
static string SplitAndJoinOnSpace(string input)
{
string[] split = input.Split(new char[] { ' '}, StringSplitOptions.RemoveEmptyEntries);
return string.Join(" ", split);
}
//StringBuilder by user214147 (https://stackoverflow.com/a/2156660/2352507
public static string user214147(string S)
{
string s = S.Trim();
bool iswhite = false;
int iwhite;
int sLength = s.Length;
StringBuilder sb = new StringBuilder(sLength);
foreach (char c in s.ToCharArray())
{
if (Char.IsWhiteSpace(c))
{
if (iswhite)
{
//Continuing whitespace ignore it.
continue;
}
else
{
//New WhiteSpace
//Replace whitespace with a single space.
sb.Append(" ");
//Set iswhite to True and any following whitespace will be ignored
iswhite = true;
}
}
else
{
sb.Append(c.ToString());
//reset iswhitespace to false
iswhite = false;
}
}
return sb.ToString();
}
//StringBuilder by fubo (https://stackoverflow.com/a/27502353/2352507
public static string fubo(this string Value)
{
StringBuilder sbOut = new StringBuilder();
if (!string.IsNullOrEmpty(Value))
{
bool IsWhiteSpace = false;
for (int i = 0; i < Value.Length; i++)
{
if (char.IsWhiteSpace(Value[i])) //Comparison with WhiteSpace
{
if (!IsWhiteSpace) //Comparison with previous Char
{
sbOut.Append(Value[i]);
IsWhiteSpace = true;
}
}
else
{
IsWhiteSpace = false;
sbOut.Append(Value[i]);
}
}
}
return sbOut.ToString();
}
//David S. 2013 (https://stackoverflow.com/a/16035044/2352507)
public static String SingleSpacedTrim(String inString)
{
StringBuilder sb = new StringBuilder();
Boolean inBlanks = false;
foreach (Char c in inString)
{
switch (c)
{
case '\r':
case '\n':
case '\t':
case ' ':
if (!inBlanks)
{
inBlanks = true;
sb.Append(' ');
}
continue;
default:
inBlanks = false;
sb.Append(c);
break;
}
}
return sb.ToString().Trim();
}
/// <summary>
/// We want to run this item with max priory to lower the odds of
/// the OS from doing program context switches in the middle of our code.
/// source:https://stackoverflow.com/a/16157458
/// </summary>
/// <returns>random seed</returns>
private static long ConfigProgramForBenchmarking()
{
//prevent the JIT Compiler from optimizing Fkt calls away
long seed = Environment.TickCount;
//use the second Core/Processor for the test
Process.GetCurrentProcess().ProcessorAffinity = new IntPtr(2);
//prevent "Normal" Processes from interrupting Threads
Process.GetCurrentProcess().PriorityClass = ProcessPriorityClass.High;
//prevent "Normal" Threads from interrupting this thread
Thread.CurrentThread.Priority = ThreadPriority.Highest;
return seed;
}
}
基准调：释放模式，无调试器连接，i7处理器，平均4次运行中，只有短字符串测试
VB.NET
Linha.Split(" ").ToList().Where(Function(x) x <> " ").ToArray
C＃
Linha.Split(" ").ToList().Where(x => x != " ").ToArray();
享受LINQ的功率= d
Regex regex = new Regex(@"\W+");
string outputString = regex.Replace(inputString, " ");
最小的解决方案：
VAR的regexp = / \ S + /克，newString = oldString.replace（正则表达式，”“）;
你可以试试这个：
/// <summary>
/// Remove all extra spaces and tabs between words in the specified string!
/// </summary>
/// <param name="str">The specified string.</param>
public static string RemoveExtraSpaces(string str)
{
str = str.Trim();
StringBuilder sb = new StringBuilder();
bool space = false;
foreach (char c in str)
{
if (char.IsWhiteSpace(c) || c == (char)9) { space = true; }
else { if (space) { sb.Append(' '); }; sb.Append(c); space = false; };
}
return sb.ToString();
}
有没有办法建立在做到这一点。 你可以试试这个：
private static readonly char[] whitespace = new char[] { ' ', '\n', '\t', '\r', '\f', '\v' };
public static string Normalize(string source)
{
return String.Join(" ", source.Split(whitespace, StringSplitOptions.RemoveEmptyEntries));
}
这将删除开头和结尾whitespce以及崩溃任何内部空白，以一个单一的空白字符。 如果你真的只想崩溃的空间，然后使用正则表达式的解决方案是更好的; 否则该解决方案是更好的。 （见分析由乔恩斯基特完成。）
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