I'm looking to replace all commas in a single string not contained within a pair of double-quotes,
with a tab. I don't know where to begin.
e.g., string line = "a,",,"b" would be changed to "a,"\t\t"b"
Can someone suggest a regex pattern to use, or any other way that will accomplish this?
TIA Flomo
--
3  1433 
I'm looking to replace all commas in a single string not contained
within a pair of double-quotes, with a tab. I don't know where to
begin.
e.g., string line = "a,",,"b" would be changed to "a,"\t\t"b"
Can someone suggest a regex pattern to use, or any other way that will
accomplish this?
You want to replace all commas preceeded by an even number of doublequotes.
Try using a look-behind pattern for that - e.g.
something like
str.replace(@"(?<=^([^""]*""[^""]*""[^""]*)*),", "\t");
>
TIA Flomo
Hello Niels,
Thank you for the suggestion.
Hello Flomo,
Niels's regex is the third method to resolve the problem. But this method
still suffers from the loss of performance.
I made a test to compare the three methods: (see the code listing 1)
The result is:
#direct operation on chars: 39ms.
#my regex: 6280ms.
#Niels's regex: 8997ms.
Therefore, I think the direct operation on chars is the best way by now.
Code Listing 1:
class Program
{
static void Main(string[] args)
{
string test = "\"a,,,,,\",\"j,dd,\"b\",\",\"";
Test1(test);
Test2(test);
Test3(test);
return;
}
public static void Test1(string test)
{
Stopwatch sw = new Stopwatch();
sw.Start();
for (int times = 0; times < 100000; times++)
{
char[] str = test.ToCharArray();
bool isInQuotes = false;
for (int i = 0; i < str.Length; i++)
{
if (!isInQuotes && str[i] == ',')
{
str[i] = '\t';
continue;
}
if (str[i] == '\"')
isInQuotes = !isInQuotes;
}
//Console.WriteLine(str);
}
sw.Stop();
Console.WriteLine(sw.ElapsedMilliseconds);
}
public static void Test3(string test)
{
Stopwatch sw = new Stopwatch();
sw.Start();
for (int times = 0; times < 100000; times++)
{
Regex regex = new Regex("(?<=^([^\"]*\"[^\"]*\"[^\"]*)*),");
regex.Replace(test, "\t");
}
sw.Stop();
Console.WriteLine(sw.ElapsedMilliseconds);
}
public static void Test2(string test)
{
Stopwatch sw = new Stopwatch();
sw.Start();
for (int times = 0; times < 100000; times++)
{
Regex regex = new
Regex("(?<head>\".*?\")*(?<remove>,*)(?<tail>\".*? \")*");
MatchEvaluator myEvaluator = new
MatchEvaluator(Program.ReplaceFunction);
regex.Replace(test, myEvaluator);
}
sw.Stop();
Console.WriteLine(sw.ElapsedMilliseconds);
}
public static string ReplaceFunction(Match m)
{
return m.Groups["head"].Value +
m.Groups["remove"].Value.Replace(',', '\t') + m.Groups["tail"].Value;
}
}
Sincerely,
Jialiang Ge (ji****@online.microsoft.com, remove 'online.')
Microsoft Online Community Support
=================================================
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so that others may learn and benefit from your issue.
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Hi Flomo,
Would you mind letting me know the result of the suggestions? If you need
further assistance, feel free to let me know. I will be more than happy to
be of assistance.
Have a great day!
Sincerely,
Jialiang Ge (ji****@online.microsoft.com, remove 'online.')
Microsoft Online Community Support
=================================================
When responding to posts, please "Reply to Group" via your newsreader
so that others may learn and benefit from your issue.
=================================================
This posting is provided "AS IS" with no warranties, and confers no rights.
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