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Split a string if delimiter is between single quotes [duplicate]

This question already has answers here:
How to split csv whose columns may contain comma
(9 answers)
Closed 4 years ago.
I have the following comma-separated string that I need to split. The problem is that some of the content is within quotes and contains commas that shouldn't be used in the split.
String:
111,222,"33,44,55",666,"77,88","99"
I want the output:
111
222
33,44,55
666
77,88
99
I have tried this:
(?:,?)((?<=")[^"]+(?=")|[^",]+)
But it reads the comma between "77,88","99" as a hit and I get the following output:
111
222
33,44,55
666
77,88
,
99

Depending on your needs you may not be able to use a csv parser, and may in fact want to re-invent the wheel!!
You can do so with some simple regex
(?:^|,)(\"(?:[^\"]+|\"\")*\"|[^,]*)
This will do the following:
(?:^|,) = Match expression "Beginning of line or string ,"
(\"(?:[^\"]+|\"\")*\"|[^,]*) = A numbered capture group, this will select between 2 alternatives:
stuff in quotes
stuff between commas
This should give you the output you are looking for.
Example code in C#
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\""));
}
Warning As per #MrE's comment - if a rogue new line character appears in a badly formed csv file and you end up with an uneven ("string) you'll get catastrophic backtracking (https://www.regular-expressions.info/catastrophic.html) in your regex and your system will likely crash (like our production system did). Can easily be replicated in Visual Studio and as I've discovered will crash it. A simple try/catch will not trap this issue either.
You should use:
(?:^|,)(\"(?:[^\"])*\"|[^,]*)
instead

Fast and easy:
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
}
With this string as input :
111,222,"33,44,55",666,"77,88","99"
It will return :
111
222
33,44,55
666
77,88
99

i really like jimplode's answer, but I think a version with yield return is a little bit more useful, so here it is:
public IEnumerable<string> SplitCSV(string input)
{
Regex csvSplit = new Regex("(?:^|,)(\"(?:[^\"]+|\"\")*\"|[^,]*)", RegexOptions.Compiled);
foreach (Match match in csvSplit.Matches(input))
{
yield return match.Value.TrimStart(',');
}
}
Maybe it's even more useful to have it like an extension method:
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(',');
}
}
}

This regular expression works without the need to loop through values and TrimStart(','), like in the accepted answer:
((?<=\")[^\"]*(?=\"(,|$)+)|(?<=,|^)[^,\"]*(?=,|$))
Here is the implementation in C#:
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);
}
Outputs
111
222
33,44,55
666
77,88
99

None of these answers work when the string has a comma inside quotes, as in "value, 1", or escaped double-quotes, as in "value ""1""", which are valid CSV that should be parsed as value, 1 and value "1", respectively.
This will also work with the tab-delimited format if you pass in a tab instead of a comma as your delimiter.
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);
}
}
}
}
}

With minor updates to the function provided by "Chad Hedgcock".
Updates are on:
Line 26: character.val == '\"' - This can never be true due to the check made on Line 24. i.e. character.val == '"'
Line 28: if (row[character.index + 1] == character.val) added !quoteIsEscaped to escape 3 consecutive quotes.
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);
}
}
}
}
}

For Jay's answer, if you use a 2nd boolean then you can have nested double-quotes inside single-quotes and vice-versa.
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;
}

The original version
Currently I use the following regex:
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);
This solution can handle pretty chaotic cases too like below:
This is how to feed the result into an array:
var data = regexCSVSplit.Matches(line_to_process).Cast<Match>().
Select(x => x.Groups["DAT"].Value).ToArray();
See this example in action HERE
Note: The regular expression contains two set of <FULL> block and each of them contains two <QUODAT> block separated by "or" (|). Depending on your task you may only need one of them.
Note: That this regular expression gives us one string array, and works on single line with or without <carrier return> and/or <line feed>.
Simplified version
The following regular expression will already cover many complex cases:
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);
See this example in action: HERE
It can process complex, easy and empty items too:
This is how to feed the result into an array:
var data = regexCSVSplit.Matches(line_to_process).Cast<Match>().
Select(x => x.Groups["DAT"].Value).ToArray();
The main rule here is that every item may contain anything but the <quotation mark><separators><comma> sequence AND each item shall being and end with the same <quotation mark>.
<quotation mark>: <">, <'>
<comma>: <,>, <;>, <tab>, <carrier return>, <line feed>
Edit notes: I added some more explanation to make it easier to understand and replaces the text "CO" with "QUO".

Try this:
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);
}

I know I'm a bit late to this, but for searches, here is how I did what you are asking about in C sharp
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;
}

Don't reinvent a CSV parser, try FileHelpers.

I needed something a little more robust, so I took from here and created this... This solution is a little less elegant and a little more verbose, but in my testing (with a 1,000,000 row sample), I found this to be 2 to 3 times faster. Plus it handles non-escaped, embedded quotes. I used string delimiter and qualifiers instead of chars because of the requirements of my solution. I found it more difficult than I expected to find a good, generic CSV parser so I hope this parsing algorithm can help someone.
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 = $"{record}{delimiter}";
for (var idx = 0; idx < row.Length; idx++)
{
// A delimiter character...
if (row[idx]== delimiter[0])
{
// Are we inside qualifier? If not, we've hit the end of a column value.
if (!inQualifier)
{
results.Add(trimData ? result.ToString().Trim() : result.ToString());
result.Clear();
inField = false;
}
else
{
result.Append(row[idx]);
}
}
// NOT a delimiter character...
else
{
// ...Not a space character
if (row[idx] != ' ')
{
// A qualifier character...
if (row[idx] == qualifier[0])
{
// Qualifier is closing qualifier...
if (inQualifier && row[IndexOfNextNonWhiteSpaceChar(row, idx + 1)] == delimiter[0])
{
inQualifier = false;
continue;
}
else
{
// ...Qualifier is opening qualifier
if (!inQualifier)
{
inQualifier = true;
}
// ...It's a qualifier inside a qualifier.
else
{
inField = true;
result.Append(row[idx]);
}
}
}
// Not a qualifier character...
else
{
result.Append(row[idx]);
inField = true;
}
}
// ...A space character
else
{
if (inQualifier || inField)
{
result.Append(row[idx]);
}
}
}
}
return results.ToArray<string>();
}
Some test code:
//var input = "111,222,\"33,44,55\",666,\"77,88\",\"99\"";
var input =
"111, 222, \"99\",\"33,44,55\" , \"666 \"mark of a man\"\", \" spaces \"77,88\" \"";
Console.WriteLine("Split with trim");
Console.WriteLine("---------------");
var result = SplitRow(input, ",", "\"", true);
foreach (var r in result)
{
Console.WriteLine(r);
}
Console.WriteLine("");
// Split 2
Console.WriteLine("Split with no trim");
Console.WriteLine("------------------");
var result2 = SplitRow(input, ",", "\"", false);
foreach (var r in result2)
{
Console.WriteLine(r);
}
Console.WriteLine("");
// Time Trial 1
Console.WriteLine("Experimental Process (1,000,000) iterations");
Console.WriteLine("-------------------------------------------");
watch = Stopwatch.StartNew();
for (var i = 0; i < 1000000; i++)
{
var x1 = SplitRow(input, ",", "\"", false);
}
watch.Stop();
elapsedMs = watch.ElapsedMilliseconds;
Console.WriteLine($"Total Process Time: {string.Format("{0:0.###}", elapsedMs / 1000.0)} Seconds");
Console.WriteLine("");
Results
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

I once had to do something similar and in the end I got stuck with Regular Expressions. The inability for Regex to have state makes it pretty tricky - I just ended up writing a simple little parser.
If you're doing CSV parsing you should just stick to using a CSV parser - don't reinvent the wheel.

Here is my fastest implementation based upon string raw pointer manipulation:
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;
}

Try this
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();
}

This is Chad's answer rewritten with state based logic. His answered failed for me when it came across """BRAD""" as a field. That should return "BRAD" but it just ate up all the remaining fields. When I tried to debug it I just ended up rewriting it as state based logic:
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());
}
This is a lot more lines of code than the other solutions, but it is easy to modify to add edge cases.

Make every other a-z letter Upper / Lower case, ignoring whitespace

Can somebody tell me what I am doing wrong please? can't seem to get the expected output, i.e. ignore whitespace and only upper/lowercase a-z characters regardless of the number of whitespace characters
my code:
var sentence = "dancing sentence";
var charSentence = sentence.ToCharArray();
var rs = "";
for (var i = 0; i < charSentence.Length; i++)
{
if (charSentence[i] != ' ')
{
if (i % 2 == 0 && charSentence[i] != ' ')
{
rs += charSentence[i].ToString().ToUpper();
}
else if (i % 2 == 1 && charSentence[i] != ' ')
{
rs += sentence[i].ToString().ToLower();
}
}
else
{
rs += " ";
}
}
Console.WriteLine(rs);
Expected output: DaNcInG sEnTeNcE
Actual output: DaNcInG SeNtEnCe

I use flag instead of i because (as you mentioned) white space made this algorithm work wrong:
var sentence = "dancing sentence";
var charSentence = sentence.ToCharArray();
var rs = "";
var flag = true;
for (var i = 0; i < charSentence.Length; i++)
{
if (charSentence[i] != ' ')
{
if (flag)
{
rs += charSentence[i].ToString().ToUpper();
}
else
{
rs += sentence[i].ToString().ToLower();
}
flag = !flag;
}
else
{
rs += " ";
}
}
Console.WriteLine(rs);

Try a simple Finite State Automata with just two states (upper == true/false); another suggestion is to use StringBuilder:
private static string ToDancing(string value) {
if (string.IsNullOrEmpty(value))
return value;
bool upper = false;
StringBuilder sb = new StringBuilder(value.Length);
foreach (var c in value)
if (char.IsLetter(c))
sb.Append((upper = !upper) ? char.ToUpper(c) : char.ToLower(c));
else
sb.Append(c);
return sb.ToString();
}
Test
var sentence = "dancing sentence";
Console.Write(ToDancing(sentence));
Outcome
DaNcInG sEnTeNcE

I think you should declare one more variable called isUpper. Now you have two variables, i indicates the index of the character that you are iterating next and isUpper indicates whether a letter should be uppercase.
You increment i as usual, but set isUpper to true at first:
// before the loop
boolean isUpper = true;
Then, rather than checking whether i is divisible by 2, check isUpper:
if (isUpper)
{
rs += charSentence[i].ToString().ToUpper();
}
else
{
rs += sentence[i].ToString().ToLower();
}
Immediately after the above if statement, "flip" isUpper:
isUpper = !isUpper;

Linq version
var sentence = "dancing sentence";
int i = 0;
string result = string.Concat(sentence.Select(x => { i += x == ' ' ? 0 : 1; return i % 2 != 0 ? char.ToUpper(x) : char.ToLower(x); }));
Sidenote:
please replace charSentence[i].ToString().ToUpper() with char.ToUpper(charSentence[i])

Thanks #Dmitry Bychenko. Best Approach. But i thought as per the OP's (might be a fresher...) mindset, what could be the solution. Here i have the code as another solution.
Lengthy code. I myself don't like but still representing
class Program
{
static void Main(string[] args)
{
var sentence = "dancing sentence large also";
string newString = string.Empty;
StringBuilder newStringdata = new StringBuilder();
string[] arr = sentence.Split(' ');
for (int i=0; i< arr.Length;i++)
{
if (i==0)
{
newString = ReturnEvenModifiedString(arr[i]);
newStringdata.Append(newString);
}
else
{
if(char.IsUpper(newString[newString.Length - 1]))
{
newString = ReturnOddModifiedString(arr[i]);
newStringdata.Append(" ");
newStringdata.Append(newString);
}
else
{
newString = ReturnEvenModifiedString(arr[i]);
newStringdata.Append(" ");
newStringdata.Append(newString);
}
}
}
Console.WriteLine(newStringdata.ToString());
Console.Read();
}
//For Even Test
private static string ReturnEvenModifiedString(string initialString)
{
string newString = string.Empty;
var temparr = initialString.ToCharArray();
for (var i = 0; i < temparr.Length; i++)
{
if (temparr[i] != ' ')
{
if (i % 2 == 0 && temparr[i] != ' ')
{
newString += temparr[i].ToString().ToUpper();
}
else
{
newString += temparr[i].ToString().ToLower();
}
}
}
return newString;
}
//For Odd Test
private static string ReturnOddModifiedString(string initialString)
{
string newString = string.Empty;
var temparr = initialString.ToCharArray();
for (var i = 0; i < temparr.Length; i++)
{
if (temparr[i] != ' ')
{
if (i % 2 != 0 && temparr[i] != ' ')
{
newString += temparr[i].ToString().ToUpper();
}
else
{
newString += temparr[i].ToString().ToLower();
}
}
}
return newString;
}
}
OUTPUT

PigLatin translate

I will create a program that translates English words into Pig Latin ... My problem with the code found below, is that the only word in the last index of the array as reported in the results? Does anyone see the error?
Thanks in advance
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void btnTrans_Click( object sender, EventArgs e )
{
string engWordText = engWord.Text.ToString();
string let1;
string restLet;
int position;
string pigLatin = "";
string vokal = "AEIOUaeiou";
// split the sentence into individual words
//string[] words = engWordText.Split(' ');
string[] transWord = engWordText.Split(' ');
// translate each word into pig latin
foreach (string word in transWord)
{
// check for empty TextBox
try
{
let1 = word.Substring(0, 1);
restLet = word.Substring(1, word.Length - 1);
position = vokal.IndexOf(let1);
if (position == -1)
{
pigLatin = restLet + let1 + "ay";
}
else
{
pigLatin = word + "way";
}
// display the translation
latinInput.Text = pigLatin.ToString();
engWord.Clear();
}
catch (System.ArgumentOutOfRangeException)
{
MessageBox.Show("Du måste skriva in ett engelskt ord", "PigLatin",
MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
} // end method translateButton_Click
// pressing enter is the same as clicking the Translate Button
private void engWordText_KeyDown( object sender, KeyEventArgs e )
{
// allow user to press enter in TextBox
if ( e.KeyCode == Keys.Enter )
btnTrans_Click( sender, e );
} // end method inputTextBox_KeyDown
} // end class PigLatinForm

You are assigning the value of pigLatin to the text box's Text property at the end of each loop, which means it will only have the last value that was assigned to it. Try this:
List<string> plWords = new List<string>();
// translate each word into pig latin
foreach (string word in transWord)
{
// check for empty TextBox
try
{
let1 = word[0];
restLet = word.Substring(1, word.Length - 1);
if (!vokal.Contains(let1))
{
pigLatin = restLet + let1 + "ay";
}
else
{
pigLatin = word + "way";
}
plWords.Add(pigLatin);
}
catch (System.ArgumentOutOfRangeException)
{
MessageBox.Show("Du måste skriva in ett engelskt ord", "PigLatin",
MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
engWord.Clear();
latinInput.Text = string.Join(" ", plWords.ToArray());
As a bit of a bonus, here's how you can make this operation quite a bit cleaner using Linq:
private static string MakePigLatin(string word)
{
const string vowels = "AEIOUaeiou";
char let1 = word[0];
string restLet = word.Substring(1, word.Length - 1);
return vowels.Contains(let1) ? word + "way" : restLet + let1 + "ay";
}
private void btnTrans_Click( object sender, EventArgs e )
{
var plWords = engWord.Text
.Split(new[]{' '}, StringSplitOptions.RemoveEmptyEntries)
.Select(MakePigLatin);
latinInput.Text = string.Join(" ", plWords);
engWord.Clear();
}

Read Text File from specific places

I have a question about read a text file, because i dont know if i'm thinking right. I want to read from specific string to specific character.
My text would look like this:
...
...
CM_ "Hello, how are you?
Rules: Don't smoke!
- love others
End";
...
CM_ "Why you?";
...// Many CM_
...
After Splited should look like that:
1. CM_
2. "Hello, how are you?
Rules: Don't smoke!
- love others
End"
3. CM_
4. "Why you?"
... // many CM_
I want to read from "CM_" till ";"
My Code i tried so far:
StreamReader fin = new StreamReader("text.txt");
string tmp = "";
tmp = fin.ReadToEnd();
if (tmp.StartsWith("CM_ ") && tmp.EndWith(";"))
{
var result = tmp.Split(new[] { '"' }).SelectMany((s, i) =>
{
if (i % 2 == 1) return new[] { s };
return s.Split(new[] { ' ', ';' }, StringSplitOptions.RemoveEmptyEntries);
}).ToList();
}
foreach (string x in result)
{
Console.WriteLine(x);
}

static void PRegex()
{
using (StreamReader fin = new StreamReader("text.txt"))
{
string tmp = fin.ReadToEnd();
var matches = Regex.Matches(tmp, "(CM_) ([^;]*);", RegexOptions.Singleline);
for (int i = 0; i < matches.Count; i++)
if (matches[i].Groups.Count == 3)
Console.WriteLine((2 * i + 1).ToString() + ". " + matches[i].Groups[1].Value + "\r\n" + (2 * (i + 1)).ToString() + ". " + matches[i].Groups[2].Value);
}
Console.ReadLine();
}
static void PLineByLine()
{
using (StreamReader fin = new StreamReader("text.txt"))
{
int index = 0;
string line = null;
string currentCMBlock = null;
bool endOfBlock = true;
while ((line = fin.ReadLine()) != null)
{
bool endOfLine = false;
while (!endOfLine)
{
if (endOfBlock)
{
int startIndex = line.IndexOf("CM_ ");
if (startIndex == -1)
{
endOfLine = true;
continue;
}
line = line.Substring(startIndex + 4, line.Length - startIndex - 4);
endOfBlock = false;
}
if (!endOfBlock)
{
int startIndex = line.IndexOf(";");
if (startIndex == -1)
{
currentCMBlock += line + "\r\n";
endOfLine = true;
continue;
}
currentCMBlock += line.Substring(0, startIndex);
if (!string.IsNullOrEmpty(currentCMBlock))
Console.WriteLine((++index) + ". CM_\r\n" + (++index) + ". " + currentCMBlock);
currentCMBlock = null;
line = line.Substring(startIndex + 1, line.Length - startIndex - 1);
endOfBlock = true;
}
}
}
}
Console.ReadLine();
}

You are reading the whole file into tmp. So, if there is any text before "CM_" then your conditional statement won't be entered.
Instead, try reading line by line with fin.ReadLine in a loop over all lines.

Read the whole file:
string FileToRead = File.ReadAllText("Path");
string GetContent(string StartAt, string EndAt, bool LastIndex)
{
string ReturnVal;
if(LastIndex)
{
ReturnVal = FileToRead.Remove(FileToRead.IndexOf(StartAt), FileToRead.IndexOf(EndAt));
Return ReturnVal;
}
else
{
ReturnVal = FileToRead.Remove(FileToRead.LastIndex(StartAt), FileToRead.LastIndex(EndAt));
Return ReturnVal;
}
}
-Hope I didn't do anything wrong here. (Free mind typing)
You read the file, and we remove all the content, infront of the first index. and all after it.
You can set it if will return the FIRST result found. or the last.
NOTE: I think it would be better to use a StringReader. (If I don't remember wrong...)
If you are to think about the memory usage of your application.

I tried something else, don't know if this is good. It still read the first Line, dont know that i did wrong here
my Code:
while ((tmp = fin.ReadLine()) != null)
{
if (tmp.StartsWith("CM_ "))
{
//string[] tmpList = tmp.Split(new Char[] { ' ', ';' }, StringSplitOptions.RemoveEmptyEntries);
var result = tmp.Split(new[] { '"' }).SelectMany((s, i) =>
{
if (i % 2 == 1) return new[] { s };
return s.Split(new[] { ' ', ';' }, StringSplitOptions.RemoveEmptyEntries);
}).ToList();
if (tmp.EndsWith(";")) break;
fin.ReadLine();
if (tmp.EndsWith(";"))
{
result.ToList();
break;
}
else
{
result.ToList();
fin.ReadLine();
}
foreach (string x in result)
{
Console.WriteLine(x);
}
}

I suggest you look into using Regular Expressions. It may be just what you need and much more flexible than Split().

Create Space Between Capital Letters and Skip Space Between Consecutive

I get the way to create space "ThisCourse" to be "This Course"
Add Space Before Capital Letter By (EtienneT) LINQ Statement
But i cannot
Create Space Betweeen This "ThisCourseID" to be "This Course ID" without space between "ID"
And Is there a way to do this in Linq ??

Well, if it has to be a single linq statement...
var s = "ThisCourseIDMoreXYeahY";
s = string.Join(
string.Empty,
s.Select((x,i) => (
char.IsUpper(x) && i>0 &&
( char.IsLower(s[i-1]) || (i<s.Count()-1 && char.IsLower(s[i+1])) )
) ? " " + x : x.ToString()));
Console.WriteLine(s);
Output: "This Course ID More X Yeah Y"

var s = "ThisCourseID";
for (var i = 1; i < s.Length; i++)
{
if (char.IsLower(s[i - 1]) && char.IsUpper(s[i]))
{
s = s.Insert(i, " ");
}
}
Console.WriteLine(s); // "This Course ID"
You can improve this using StringBuilder if you are going to use this on very long strings, but for your purpose, as you presented it, it should work just fine.
FIX:
var s = "ThisCourseIDSomething";
for (var i = 1; i < s.Length - 1; i++)
{
if (char.IsLower(s[i - 1]) && char.IsUpper(s[i]) ||
s[i - 1] != ' ' && char.IsUpper(s[i]) && char.IsLower(s[i + 1]))
{
s = s.Insert(i, " ");
}
}
Console.WriteLine(s); // This Course ID Something

You don't need LINQ - but you could 'enumerate' and use lambda to make it more generic...
(though not sure if any of this makes sense)
static IEnumerable<string> Split(this string text, Func<char?, char?, char, int?> shouldSplit)
{
StringBuilder output = new StringBuilder();
char? before = null;
char? before2nd = null;
foreach (var c in text)
{
var where = shouldSplit(before2nd, before, c);
if (where != null)
{
var str = output.ToString();
switch(where)
{
case -1:
output.Remove(0, str.Length -1);
yield return str.Substring(0, str.Length - 1);
break;
case 0: default:
output.Clear();
yield return str;
break;
}
}
output.Append(c);
before2nd = before;
before = c;
}
yield return output.ToString();
}
...and call it like this e.g. ...
static IEnumerable<string> SplitLines(this string text)
{
return text.Split((before2nd, before, now) =>
{
if ((before2nd ?? 'A') == '\r' && (before ?? 'A') == '\n') return 0; // split on 'now'
return null; // don't split
});
}
static IEnumerable<string> SplitOnCase(this string text)
{
return text.Split((before2nd, before, now) =>
{
if (char.IsLower(before ?? 'A') && char.IsUpper(now)) return 0; // split on 'now'
if (char.IsUpper(before2nd ?? 'a') && char.IsUpper(before ?? 'a') && char.IsLower(now)) return -1; // split one char before
return null; // don't split
});
}
...and somewhere...
var text = "ToSplitOrNotToSplitTHEQuestionIsNow";
var words = text.SplitOnCase();
foreach (var word in words)
Console.WriteLine(word);
text = "To\r\nSplit\r\nOr\r\nNot\r\nTo\r\nSplit\r\nTHE\r\nQuestion\r\nIs\r\nNow";
words = text.SplitLines();
foreach (var word in words)
Console.WriteLine(word);
:)