我需要拆分以下逗号分隔的字符串。问题是某些内容在引号内并包含不应在拆分中使用的逗号。
字符串：
111,222,"33,44,55",666,"77,88","99"
我想要输出：
111
222
33,44,55
666
77,88
99
我试过这个：
(?:,?)((?<=")[^"]+(?=")|[^",]+)
但它读取“77,88”，“99”之间的逗号作为命中，我得到以下输出：
111
222
33,44,55
666
77,88
,
99
【问题讨论】：
根据您的需要，您可能无法使用 csv 解析器，实际上可能想要重新发明轮子！！
你可以用一些简单的正则表达式来做到这一点
(?:^|,)(\"(?:[^\"]+|\"\")*\"|[^,]*)
这将执行以下操作：
(?:^|,) = 匹配表达式“行或字符串的开头,”
(\"(?:[^\"]+|\"\")*\"|[^,]*) = 一个编号的捕获组，这将在 2 个备选方案之间进行选择：
这应该会给你你正在寻找的输出。
C# 中的示例代码
static Regex csvSplit = new Regex("(?:^|,)(\"(?:[^\"]+|\"\")*\"|[^,]*)", RegexOptions.Compiled);
public static string[] SplitCSV(string input)
{
List<string> list = new List<string>();
string curr = null;
foreach (Match match in csvSplit.Matches(input))
{
curr = match.Value;
if (0 == curr.Length)
{
list.Add("");
}
list.Add(curr.TrimStart(','));
}
return list.ToArray();
}
private void button1_Click(object sender, RoutedEventArgs e)
{
Console.WriteLine(SplitCSV("111,222,\"33,44,55\",666,\"77,88\",\"99\""));
}
警告根据@MrE 的评论 - 如果一个流氓换行符出现在格式错误的 csv 文件中，并且您最终得到一个不均匀的（“字符串）”，您将获得灾难性的回溯（@987654321 @) 在你的正则表达式中，你的系统可能会崩溃（就像我们的生产系统那样）。可以很容易地在 Visual Studio 中复制，我发现它会崩溃。一个简单的 try/catch 也不会捕获这个问题。
你应该使用：
(?:^|,)(\"(?:[^\"])*\"|[^,]*)
改为
【讨论】：
whatever,"""1,2,3,4,6(31/01/14)11(5) ,12 (MINIMUM 4 STAR WELS, TAPS , SHOWER & WC'S ),13,14,15,A""",another column，因为它被拆分为whatever、""、"1,2,3,4,6(31/01/14)11(5) ,12 (MINIMUM 4 STAR WELS, TAPS , SHOWER & WC'S ),13,14,15,A"、""、another column。对 Regex 的更新有何想法？
(?:^|,)(\"(?:[^\"])*\"|[^,]*) 覆盖它而没有这个问题，这会产生灾难性的回溯，并且更简单。
快速简单：
public static string[] SplitCsv(string line)
{
List<string> result = new List<string>();
StringBuilder currentStr = new StringBuilder("");
bool inQuotes = false;
for (int i = 0; i < line.Length; i++) // For each character
{
if (line[i] == '\"') // Quotes are closing or opening
inQuotes = !inQuotes;
else if (line[i] == ',') // Comma
{
if (!inQuotes) // If not in quotes, end of current string, add it to result
{
result.Add(currentStr.ToString());
currentStr.Clear();
}
else
currentStr.Append(line[i]); // If in quotes, just add it
}
else // Add any other character to current string
currentStr.Append(line[i]);
}
result.Add(currentStr.ToString());
return result.ToArray(); // Return array of all strings
}
将此字符串作为输入：
111,222,"33,44,55",666,"77,88","99"
它会返回：
111
222
33,44,55
666
77,88
99
【讨论】：
我真的很喜欢 jimplode 的回答，但我认为有 yield return 的版本更有用，所以这里是：
public IEnumerable<string> SplitCSV(string input)
{
Regex csvSplit = new Regex("(?:^|,)(\"(?:[^\"]+|\"\")*\"|[^,]*)", RegexOptions.Compiled);
foreach (Match match in csvSplit.Matches(input))
{
yield return match.Value.TrimStart(',');
}
}
也许将它像扩展方法一样使用会更有用：
public static class StringHelper
{
public static IEnumerable<string> SplitCSV(this string input)
{
Regex csvSplit = new Regex("(?:^|,)(\"(?:[^\"]+|\"\")*\"|[^,]*)", RegexOptions.Compiled);
foreach (Match match in csvSplit.Matches(input))
{
yield return match.Value.TrimStart(',');
}
}
}
【讨论】：
此正则表达式无需遍历值和 TrimStart(',') 即可工作，就像在接受的答案中一样：
((?<=\")[^\"]*(?=\"(,|$)+)|(?<=,|^)[^,\"]*(?=,|$))
这是 C# 中的实现：
string values = "111,222,\"33,44,55\",666,\"77,88\",\"99\"";
MatchCollection matches = new Regex("((?<=\")[^\"]*(?=\"(,|$)+)|(?<=,|^)[^,\"]*(?=,|$))").Matches(values);
foreach (var match in matches)
{
Console.WriteLine(match);
}
输出
111
222
33,44,55
666
77,88
99
【讨论】：
whatever,"""1,2,3,4,6(31/01/14)11(5) ,12 (MINIMUM 4 STAR WELS, TAPS , SHOWER & WC'S ),13,14,15,A""",another column，因为它被拆分为whatever、""、"1,2,3,4,6(31/01/14)11(5) ,12 (MINIMUM 4 STAR WELS, TAPS , SHOWER & WC'S ),13,14,15,A"、""、another column。对 Regex 的更新有何想法？
当字符串在引号内有逗号（如"value, 1"）或转义双引号（如"value ""1"""）时，这些答案都不起作用，它们是valid CSV，应该被解析为value, 1和@ 987654325@，分别。
如果您传入制表符而不是逗号作为分隔符，这也适用于制表符分隔的格式。
public static IEnumerable<string> SplitRow(string row, char delimiter = ',')
{
var currentString = new StringBuilder();
var inQuotes = false;
var quoteIsEscaped = false; //Store when a quote has been escaped.
row = string.Format("{0}{1}", row, delimiter); //We add new cells at the delimiter, so append one for the parser.
foreach (var character in row.Select((val, index) => new {val, index}))
{
if (character.val == delimiter) //We hit a delimiter character...
{
if (!inQuotes) //Are we inside quotes? If not, we've hit the end of a cell value.
{
Console.WriteLine(currentString);
yield return currentString.ToString();
currentString.Clear();
}
else
{
currentString.Append(character.val);
}
} else {
if (character.val != ' ')
{
if(character.val == '"') //If we've hit a quote character...
{
if(character.val == '\"' && inQuotes) //Does it appear to be a closing quote?
{
if (row[character.index + 1] == character.val) //If the character afterwards is also a quote, this is to escape that (not a closing quote).
{
quoteIsEscaped = true; //Flag that we are escaped for the next character. Don't add the escaping quote.
}
else if (quoteIsEscaped)
{
quoteIsEscaped = false; //This is an escaped quote. Add it and revert quoteIsEscaped to false.
currentString.Append(character.val);
}
else
{
inQuotes = false;
}
}
else
{
if (!inQuotes)
{
inQuotes = true;
}
else
{
currentString.Append(character.val); //...It's a quote inside a quote.
}
}
}
else
{
currentString.Append(character.val);
}
}
else
{
if (!string.IsNullOrWhiteSpace(currentString.ToString())) //Append only if not new cell
{
currentString.Append(character.val);
}
}
}
}
}
【讨论】：
对“Chad Hedgcock”提供的功能进行了小幅更新。
更新正在进行中：
第 26 行：character.val == '\"' - 由于第 24 行的检查，这永远不会是真的。即 character.val == '"'
第 28 行：如果 (row[character.index + 1] == character.val) 添加了 !quoteIsEscaped 以转义 3 个连续的引号。
public static IEnumerable<string> SplitRow(string row, char delimiter = ',')
{
var currentString = new StringBuilder();
var inQuotes = false;
var quoteIsEscaped = false; //Store when a quote has been escaped.
row = string.Format("{0}{1}", row, delimiter); //We add new cells at the delimiter, so append one for the parser.
foreach (var character in row.Select((val, index) => new {val, index}))
{
if (character.val == delimiter) //We hit a delimiter character...
{
if (!inQuotes) //Are we inside quotes? If not, we've hit the end of a cell value.
{
//Console.WriteLine(currentString);
yield return currentString.ToString();
currentString.Clear();
}
else
{
currentString.Append(character.val);
}
} else {
if (character.val != ' ')
{
if(character.val == '"') //If we've hit a quote character...
{
if(character.val == '"' && inQuotes) //Does it appear to be a closing quote?
{
if (row[character.index + 1] == character.val && !quoteIsEscaped) //If the character afterwards is also a quote, this is to escape that (not a closing quote).
{
quoteIsEscaped = true; //Flag that we are escaped for the next character. Don't add the escaping quote.
}
else if (quoteIsEscaped)
{
quoteIsEscaped = false; //This is an escaped quote. Add it and revert quoteIsEscaped to false.
currentString.Append(character.val);
}
else
{
inQuotes = false;
}
}
else
{
if (!inQuotes)
{
inQuotes = true;
}
else
{
currentString.Append(character.val); //...It's a quote inside a quote.
}
}
}
else
{
currentString.Append(character.val);
}
}
else
{
if (!string.IsNullOrWhiteSpace(currentString.ToString())) //Append only if not new cell
{
currentString.Append(character.val);
}
}
}
}
}
【讨论】：
对于 Jay 的回答，如果您使用第二个布尔值，那么您可以在单引号内嵌套双引号，反之亦然。
private string[] splitString(string stringToSplit)
{
char[] characters = stringToSplit.ToCharArray();
List<string> returnValueList = new List<string>();
string tempString = "";
bool blockUntilEndQuote = false;
bool blockUntilEndQuote2 = false;
int characterCount = 0;
foreach (char character in characters)
{
characterCount = characterCount + 1;
if (character == '"' && !blockUntilEndQuote2)
{
if (blockUntilEndQuote == false)
{
blockUntilEndQuote = true;
}
else if (blockUntilEndQuote == true)
{
blockUntilEndQuote = false;
}
}
if (character == '\'' && !blockUntilEndQuote)
{
if (blockUntilEndQuote2 == false)
{
blockUntilEndQuote2 = true;
}
else if (blockUntilEndQuote2 == true)
{
blockUntilEndQuote2 = false;
}
}
if (character != ',')
{
tempString = tempString + character;
}
else if (character == ',' && (blockUntilEndQuote == true || blockUntilEndQuote2 == true))
{
tempString = tempString + character;
}
else
{
returnValueList.Add(tempString);
tempString = "";
}
if (characterCount == characters.Length)
{
returnValueList.Add(tempString);
tempString = "";
}
}
string[] returnValue = returnValueList.ToArray();
return returnValue;
}
【讨论】：
目前我使用以下正则表达式：
public static Regex regexCSVSplit = new Regex(@"(?x:(
(?<FULL>
(^|[,;\t\r\n])\s*
( (?<QUODAT> (?<QUO>[""'])(?<DAT>([^,;\t\r\n]|(?<!\k<QUO>\s*)[,;\t\r\n])*)\k<QUO>) |
(?<QUODAT> (?<DAT> [^""',;\s\r\n]* )) )
(?=\s*([,;\t\r\n]|$))
) |
(?<FULL>
(^|[\s\t\r\n])
( (?<QUODAT> (?<QUO>[""'])(?<DAT> [^""',;\s\t\r\n]* )\k<QUO>) |
(?<QUODAT> (?<DAT> [^""',;\s\t\r\n]* )) )
(?=[,;\s\t\r\n]|$)
)
))", RegexOptions.Compiled);
这是将结果输入数组的方法：
var data = regexCSVSplit.Matches(line_to_process).Cast<Match>().
Select(x => x.Groups["DAT"].Value).ToArray();
查看此示例的实际操作HERE
注意：正则表达式包含两组<FULL>块，每组包含两个<QUODAT>块，用“或”分隔（|）。根据您的任务，您可能只需要其中一个。
注意：这个正则表达式为我们提供了一个字符串数组，并且可以在有或没有<carrier return> 和/或<line feed> 的情况下处理单行。
下面的正则表达式已经涵盖了很多复杂的情况：
public static Regex regexCSVSplit = new Regex(@"(?x:(
(?<FULL>
(^|[,;\t\r\n])\s*
(?<QUODAT> (?<QUO>[""'])(?<DAT>([^,;\t\r\n]|(?<!\k<QUO>\s*)[,;\t\r\n])*)\k<QUO>)
(?=\s*([,;\t\r\n]|$))
)
))", RegexOptions.Compiled);
查看这个示例：HERE
这是将结果输入数组的方法：
var data = regexCSVSplit.Matches(line_to_process).Cast<Match>().
Select(x => x.Groups["DAT"].Value).ToArray();
这里的主要规则是每个项目都可以包含除<quotation mark><separators><comma> 序列之外的任何内容，并且每个项目都应以相同的<quotation mark> 结尾。
<quotation mark>: <">, <'>
<comma>: <,>, <;>, <tab>, <carrier return>, <line feed>
编辑注释：我添加了更多解释以使其更易于理解并将文本“CO”替换为“QUO”。
【讨论】：
"E", "Z"字符串的解决方案
"E", "Z" 等简单案例或更复杂的案例。
试试这个：
string s = @"111,222,""33,44,55"",666,""77,88"",""99""";
List<string> result = new List<string>();
var splitted = s.Split('"').ToList<string>();
splitted.RemoveAll(x => x == ",");
foreach (var it in splitted)
{
if (it.StartsWith(",") || it.EndsWith(","))
{
var tmp = it.TrimEnd(',').TrimStart(',');
result.AddRange(tmp.Split(','));
}
else
{
if(!string.IsNullOrEmpty(it)) result.Add(it);
}
}
//Results:
foreach (var it in result)
{
Console.WriteLine(it);
}
【讨论】：
我知道我对此有点晚了，但是对于搜索，这就是我在升 C 中所做的你所问的事情
private string[] splitString(string stringToSplit)
{
char[] characters = stringToSplit.ToCharArray();
List<string> returnValueList = new List<string>();
string tempString = "";
bool blockUntilEndQuote = false;
int characterCount = 0;
foreach (char character in characters)
{
characterCount = characterCount + 1;
if (character == '"')
{
if (blockUntilEndQuote == false)
{
blockUntilEndQuote = true;
}
else if (blockUntilEndQuote == true)
{
blockUntilEndQuote = false;
}
}
if (character != ',')
{
tempString = tempString + character;
}
else if (character == ',' && blockUntilEndQuote == true)
{
tempString = tempString + character;
}
else
{
returnValueList.Add(tempString);
tempString = "";
}
if (characterCount == characters.Length)
{
returnValueList.Add(tempString);
tempString = "";
}
}
string[] returnValue = returnValueList.ToArray();
return returnValue;
}
【讨论】：
Don't reinvent CSV 解析器，试试FileHelpers。
【讨论】：
我需要一些更强大的东西，所以我从这里获取并创建了这个......这个解决方案不太优雅，也更冗长，但在我的测试中（使用 1,000,000 行样本），我发现了这个要快 2 到 3 倍。此外，它还可以处理非转义的嵌入式引号。由于我的解决方案的要求，我使用了字符串分隔符和限定符而不是字符。我发现找到一个好的通用 CSV 解析器比我预期的要困难，所以我希望这个解析算法可以帮助某人。
public static string[] SplitRow(string record, string delimiter, string qualifier, bool trimData)
{
// In-Line for example, but I implemented as string extender in production code
Func <string, int, int> IndexOfNextNonWhiteSpaceChar = delegate (string source, int startIndex)
{
if (startIndex >= 0)
{
if (source != null)
{
for (int i = startIndex; i < source.Length; i++)
{
if (!char.IsWhiteSpace(source[i]))
{
return i;
}
}
}
}
return -1;
};
var results = new List<string>();
var result = new StringBuilder();
var inQualifier = false;
var inField = false;
// We add new columns at the delimiter, so append one for the parser.
var row = $"{record}{delimiter}";
for (var idx = 0; idx < row.Length; idx++)
{
// A delimiter character...
if (row[idx]== delimiter[0])
{
// Are we inside qualifier? If not, we've hit the end of a column value.
if (!inQualifier)
{
results.Add(trimData ? result.ToString().Trim() : result.ToString());
result.Clear();
inField = false;
}
else
{
result.Append(row[idx]);
}
}
// NOT a delimiter character...
else
{
// ...Not a space character
if (row[idx] != ' ')
{
// A qualifier character...
if (row[idx] == qualifier[0])
{
// Qualifier is closing qualifier...
if (inQualifier && row[IndexOfNextNonWhiteSpaceChar(row, idx + 1)] == delimiter[0])
{
inQualifier = false;
continue;
}
else
{
// ...Qualifier is opening qualifier
if (!inQualifier)
{
inQualifier = true;
}
// ...It's a qualifier inside a qualifier.
else
{
inField = true;
result.Append(row[idx]);
}
}
}
// Not a qualifier character...
else
{
result.Append(row[idx]);
inField = true;
}
}
// ...A space character
else
{
if (inQualifier || inField)
{
result.Append(row[idx]);
}
}
}
}
return results.ToArray<string>();
}
一些测试代码：
//var input = "111,222,\"33,44,55\",666,\"77,88\",\"99\"";
var input =
"111, 222, \"99\",\"33,44,55\" , \"666 \"mark of a man\"\", \" spaces \"77,88\" \"";
Console.WriteLine("Split with trim");
Console.WriteLine("---------------");
var result = SplitRow(input, ",", "\"", true);
foreach (var r in result)
{
Console.WriteLine(r);
}
Console.WriteLine("");
// Split 2
Console.WriteLine("Split with no trim");
Console.WriteLine("------------------");
var result2 = SplitRow(input, ",", "\"", false);
foreach (var r in result2)
{
Console.WriteLine(r);
}
Console.WriteLine("");
// Time Trial 1
Console.WriteLine("Experimental Process (1,000,000) iterations");
Console.WriteLine("-------------------------------------------");
watch = Stopwatch.StartNew();
for (var i = 0; i < 1000000; i++)
{
var x1 = SplitRow(input, ",", "\"", false);
}
watch.Stop();
elapsedMs = watch.ElapsedMilliseconds;
Console.WriteLine($"Total Process Time: {string.Format("{0:0.###}", elapsedMs / 1000.0)} Seconds");
Console.WriteLine("");
结果
Split with trim
---------------
111
222
99
33,44,55
666 "mark of a man"
spaces "77,88"
Split with no trim
------------------
111
222
99
33,44,55
666 "mark of a man"
spaces "77,88"
Original Process (1,000,000) iterations
-------------------------------
Total Process Time: 7.538 Seconds
Experimental Process (1,000,000) iterations
--------------------------------------------
Total Process Time: 3.363 Seconds
【讨论】：
我曾经不得不做类似的事情，最后我被正则表达式卡住了。 Regex 无法拥有状态使其非常棘手 - 我刚刚写了一个简单的小解析器。
如果您要进行 CSV 解析，您应该坚持使用 CSV 解析器 - 不要重新发明轮子。
【讨论】：
这是我基于字符串原始指针操作的最快实现：
string[] FastSplit(string sText, char? cSeparator = null, char? cQuotes = null)
{
string[] oTokens;
if (null == cSeparator)
{
cSeparator = DEFAULT_PARSEFIELDS_SEPARATOR;
}
if (null == cQuotes)
{
cQuotes = DEFAULT_PARSEFIELDS_QUOTE;
}
unsafe
{
fixed (char* lpText = sText)
{
#region Fast array estimatation
char* lpCurrent = lpText;
int nEstimatedSize = 0;
while (0 != *lpCurrent)
{
if (cSeparator == *lpCurrent)
{
nEstimatedSize++;
}
lpCurrent++;
}
nEstimatedSize++; // Add EOL char(s)
string[] oEstimatedTokens = new string[nEstimatedSize];
#endregion
#region Parsing
char[] oBuffer = new char[sText.Length];
int nIndex = 0;
int nTokens = 0;
lpCurrent = lpText;
while (0 != *lpCurrent)
{
if (cQuotes == *lpCurrent)
{
// Quotes parsing
lpCurrent++; // Skip quote
nIndex = 0; // Reset buffer
while (
(0 != *lpCurrent)
&& (cQuotes != *lpCurrent)
)
{
oBuffer[nIndex] = *lpCurrent; // Store char
lpCurrent++; // Move source cursor
nIndex++; // Move target cursor
}
}
else if (cSeparator == *lpCurrent)
{
// Separator char parsing
oEstimatedTokens[nTokens++] = new string(oBuffer, 0, nIndex); // Store token
nIndex = 0; // Skip separator and Reset buffer
}
else
{
// Content parsing
oBuffer[nIndex] = *lpCurrent; // Store char
nIndex++; // Move target cursor
}
lpCurrent++; // Move source cursor
}
// Recover pending buffer
if (nIndex > 0)
{
// Store token
oEstimatedTokens[nTokens++] = new string(oBuffer, 0, nIndex);
}
// Build final tokens list
if (nTokens == nEstimatedSize)
{
oTokens = oEstimatedTokens;
}
else
{
oTokens = new string[nTokens];
Array.Copy(oEstimatedTokens, 0, oTokens, 0, nTokens);
}
#endregion
}
}
// Epilogue
return oTokens;
}
【讨论】：
试试这个
private string[] GetCommaSeperatedWords(string sep, string line)
{
List<string> list = new List<string>();
StringBuilder word = new StringBuilder();
int doubleQuoteCount = 0;
for (int i = 0; i < line.Length; i++)
{
string chr = line[i].ToString();
if (chr == "\"")
{
if (doubleQuoteCount == 0)
doubleQuoteCount++;
else
doubleQuoteCount--;
continue;
}
if (chr == sep && doubleQuoteCount == 0)
{
list.Add(word.ToString());
word = new StringBuilder();
continue;
}
word.Append(chr);
}
list.Add(word.ToString());
return list.ToArray();
}
【讨论】：
这是 Chad 用基于状态的逻辑重写的答案。当遇到"""BRAD""" 作为一个字段时，他的回答对我来说失败了。那应该返回 "BRAD" 但它只是吃掉了所有剩余的字段。当我尝试调试它时，我只是将它重写为基于状态的逻辑：
enum SplitState { s_begin, s_infield, s_inquotefield, s_foundquoteinfield };
public static IEnumerable<string> SplitRow(string row, char delimiter = ',')
{
var currentString = new StringBuilder();
SplitState state = SplitState.s_begin;
row = string.Format("{0}{1}", row, delimiter); //We add new cells at the delimiter, so append one for the parser.
foreach (var character in row.Select((val, index) => new { val, index }))
{
//Console.WriteLine("character = " + character.val + " state = " + state);
switch (state)
{
case SplitState.s_begin:
if (character.val == delimiter)
{
/* empty field */
yield return currentString.ToString();
currentString.Clear();
} else if (character.val == '"')
{
state = SplitState.s_inquotefield;
} else
{
currentString.Append(character.val);
state = SplitState.s_infield;
}
break;
case SplitState.s_infield:
if (character.val == delimiter)
{
/* field with data */
yield return currentString.ToString();
state = SplitState.s_begin;
currentString.Clear();
} else
{
currentString.Append(character.val);
}
break;
case SplitState.s_inquotefield:
if (character.val == '"')
{
// could be end of field, or escaped quote.
state = SplitState.s_foundquoteinfield;
} else
{
currentString.Append(character.val);
}
break;
case SplitState.s_foundquoteinfield:
if (character.val == '"')
{
// found escaped quote.
currentString.Append(character.val);
state = SplitState.s_inquotefield;
}
else if (character.val == delimiter)
{
// must have been last quote so we must find delimiter
yield return currentString.ToString();
state = SplitState.s_begin;
currentString.Clear();
}
else
{
throw new Exception("Quoted field not terminated.");
}
break;
default:
throw new Exception("unknown state:" + state);
}
}
//Console.WriteLine("currentstring = " + currentString.ToString());
}
这比其他解决方案要多得多的代码行，但很容易修改以添加边缘情况。
【讨论】：