string.format syntax in c# and what it does?

Question

I am currently trying to modify a script for a SSIS project to import data from a dynamic .txt file (sometimes colums are added).

I am new to c# and the only problem in the script is that it contains a string format expression that I really can't graps so my question is:

What does this do?

string _Statement = String.Format ("{0}(?=(?:[^{1}]*{1}[^{1}]*{1})*(?![^{1}]*{1}))"

The parameters are

  {0} = First line in the file containing all the column headers
  {1} = Semicolon delimiter

Any help in this would be much appreciated.

Tim Schmelter · Accepted Answer · 2013-11-26 14:28:55Z

3

Since the same index is used repetitively, the same value is inserted.

So {0} will be replaced with

 First line in the file containing all the column headers

and all occurences of {1} will be replaced by

Semicolon delimiter

However, the code above seems to be incomplete since i'm missing the parameter list at the end of string.Format. Something like:

string _Statement = String.Format("{0}(?=(?:[^{1}]*{1}[^{1}]*{1})*(?![^{1}]*{1}))"
                                   , firstLine , ";");

Presuming that the line is: TEST-LINE this is the result:

"TEST-LINE(?=(?:[^;]*;[^;]*;)*(?![^;]*;))"

edited Nov 26, 2013 at 14:28

answered Nov 26, 2013 at 14:22

Tim Schmelter

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1 Comment

user3036771 Over a year ago

Seems that i can't upvote due to lack of reputation, but this answer explains the question. Thank you!

David Arno · Accepted Answer · 2013-11-26 14:24:25Z

0

The String.Format method here replaces all occurrences of {0} with First line in the file containing all the column headers and all occurrences of {1} with Semicolon delimiter. The resultant string will be a regular expression (regex) in this case.

answered Nov 26, 2013 at 14:24

David Arno

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user3036771 Over a year ago

Thank you that explains it! I guess that makes the question faulty due to the fact it is regex that I don't understand and not string.format. Now i have something to work with alteast!

Kevin Brechbühl · Accepted Answer · 2013-11-26 14:28:04Z

0

String.Format formats your string, so each parameter within {} will be replaced with a value which you also have to specify. In your example, all values with {0} will be replaced with

First line in the file containing all the column headers

and all values with {1} will be replaced with

Semicolon delimiter

You have to specify this two values as parameters to String.Format, so your code should look like:

string first = "col1,col2,col3";
string second = ";";
string _Statement = String.Format("{0}(?=(?:[^{1}]*{1}[^{1}]*{1})*(?![^{1}]*{1}))", first, second);

And the result will be

_Statement = "col1,col2,col3(?=(?:[^;]*;[^;]*;)*(?![^;]*;))";

answered Nov 26, 2013 at 14:28

Kevin Brechbühl

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