split using regular expression

Question

Hi,

I try to split a content of a string using regular expression but I keep getting a blank at the begin and the  last of the return array substring

the string I try to split is in this format

"AAA","BBB","CCC,DDD,EEE,FFF"

"AAA","BBB","CCC,DDD,EEE,FFF,GGG,EEE"

"AAA","BBB","CCC,DDD,EEE,FFF,GGG"

 

                  using (TextReader m_tr = new StreamReader(m_file, Encoding.Default))
                {

                    string m_line;
                    string[] m_columns;
                    System.Text.RegularExpressions.Regex m_regexp = new System.Text.RegularExpressions.Regex("^\"|\"[,]\"|\"$");
                   

                    while ((m_line = m_tr.ReadLine()) != null)
                    {
                        m_columns = m_regexp.Split(m_line);

                        foreach (string m_column in m_columns)
                        {
                            MessageBox.Show(m_column);   //first and last showing blank
                        }
                    }
                }

 

how do I get ride of the blank?

Answer 1

Try this:

        static void splitTest()
        {
            using (TextReader m_tr = new StreamReader(m_file, Encoding.Default))
            System.Text.RegularExpressions.MatchCollection m_columns;
            System.Text.RegularExpressions.Regex m_regexp = new System.Text.RegularExpressions.Regex(@"\w+[,\w+]*");

            while ((m_line = m_tr.ReadLine()) != null)
            {
                m_columns = m_regexp.Matches(m_line);

                foreach (System.Text.RegularExpressions.Match col in m_columns)
                {
                    MessageBox.Show(col.Value);
                }
            }
        }

Answer 2

Thanks for the reply, the regular expression  does not return the result I want.

 I change to the regular expression  to this in order to get the result I want.

System.Text.RegularExpressions.Regex m_regexp = new System.Text.RegularExpressions.Regex("\"([^\"]*)\"");



the only problem is the double quotation sign include in the return , which I remove using trim()

"AAA","BBB","CCC,DDD,EEE,FFF"

become

"AAA"

"BBB"

"CCC,DDD,EEE,FFF"  

 

I wonder If I can get the return (without double quotation)  from regular expression without need to use trim?

 

 

 

Try this:

 

        static void splitTest()
        {
            using (TextReader m_tr = new StreamReader(m_file, Encoding.Default))
            System.Text.RegularExpressions.MatchCollection m_columns;
            System.Text.RegularExpressions.Regex m_regexp = new System.Text.RegularExpressions.Regex(@"\w+[,\w+]*");

            while ((m_line = m_tr.ReadLine()) != null)
            {
                m_columns = m_regexp.Matches(m_line);

                foreach (System.Text.RegularExpressions.Match col in m_columns)
                {
                    MessageBox.Show(col.Value);
                }
            }
        }

Answer 3

Hi charles c,

you can try this regex:

[",]+

 

the result is shown here: http://regexr.com?2uvnh

 

happy coding...

---

"It's time to kick ass and chew bubble gum... and I'm all outta gum." - Duke Nukem

Answer 4

I don't think that's how it works. When you want to use Split() to remove certain string for you, it'll using this as seperator. So you'll find a leading and trilling set if you use it this way.

You may consider adding suggestion to MS Connect requesting new flag like StringSplitOptions.RemoveEmptyEntries you get in String.Split(). I've searched a bit and found no similar suggestion, so you can begin add your entry if you wish.

@Do Django: You example is also not what charles needed because he don't want the comma in doublequotes be used as seperator.

Answer 5

You can use group instead of split .. Try below piece of code 

   using (TextReader m_tr = new StreamReader(m_file, Encoding.Default))

                   {

 

                       string m_line;

                       string[] m_columns;

 

                       //string is the name of the group

                       string expression = "\"(?<string>.[^\"]*)\"";

 

                       System.Text.RegularExpressions.Regex m_regexp = new System.Text.RegularExpressions.Regex(expression);

 

 

                       while ((m_line = m_tr.ReadLine()) != null)

                       {

                         MatchCollection mCollection= m_regexp.Matches(m_line);

 

                            foreach (Match m_column in mCollection)

                           {

                               // MessageBox.Show(m_column);   //first and last showing blank

 

                               Console.WriteLine(m_column.Groups["string"].Value);

 

 

                           }

                       }

                   }

Answer 6

oh, sorry for the misunderstanding, please try this:

 

["],?"?

 

you can see it here: http://regexr.com?2uvsv

Did I get it right now?

 

regards

---

"It's time to kick ass and chew bubble gum... and I'm all outta gum." - Duke Nukem

Answer 7

You got it correct this time. However because of how RegEx.Split() works, the original poster will still get a leading and trailing empty member in the returned array.

Answer 8

Hi charles,

How's it going? Do you have any updates about the previous issue?

---

Bob Shen [MSFT]
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