Regular expression problem - Replacing a pattern

[Dimitris Georgakopuolos]

Hello,

I have a text file that I load up to a string. The text includes
certain expression like {firstName} or {userName} that I want to match
and then replace with a new expression. However, I want to use the
text included within the brackets to do a lookup so that I can replace
the expression with the new text.

For example:

Lets say the text file reads:
Hello {firstName}, Your account {accountName} has been updated.

I need to figure out how to write the expression so that the string
reads like:
Hello Dimitris, Your account Hotmail has been updated.

after the replacement. Keep in mind that I need to use the value
contained in the brackets so that I can do a lookup to figure what the
corresponding replacement is.

Any help would be appreciated.

Dimitris

[Boris]

aaaaaaaaaaaaaaa aaa
"Michael Voss" <mi**********@l vrREMOVE.deCAPS > wrote in message
news:40876fea$1 @news...

Oops - I should rather test the code I give away before posting...
I missed a very important "*" for the Regex to match not just one character between {}...

As Du pointed out, the { and } will have to be escaped. Then, you are
looking for everything between \{ and \}, so the regular expression to start

with would be "\{.*\}" which would detect wether there is any occurrence

of a
^
--------------------| need a "*" here to match more than one character

!!!!

pair of curly brackets in your string. Remember to put an @ in front of your

regular expression string, so C# knows the \ belong into your string and

are

not C#-escape-characters.
You will most likely want to find the shortest pair, as the expression

above

would find one occurence in our string, containing "firstName} , Your
account {accountName" between the pair of brackets. So we make the .*

"lazy"
^
----------------------------------------------------------------------|
need another "*" here to match more than one character !!!!

by adding a "?" behind. That makes "\{.*?\}" for our improved expression. ^
-----------------------------------------|
and another "*" goes here !!!!!!

This expression will match twice, with "firstname" and "accountnam e"
included between the two pairs of brackets.
Next, you want to remember the value that matches the regular

expression, so

we crate a named group: "\{(?'groupname '.*?)\}". This will find any sequence
^
-------------------------------------------|
ok, another "*" here ...

of characters (.*?) between a pair of curly brackets (\{ and \}) and

store it
^
------------------|
and "*" here again !!!!

in the group named "groupname" for each match. ?'groupname' names the group

(you can use ?<groupname> instead) and everything else between the ()

makes

the expression, that will be stored in the group "groupname" .
Finally, we want to iterate over the matches:

=============== =============== =============== =============== =============== =
string myString = "Hello {firstName}, Your account {accountName} has been updated.";

// Create a new regular expression
// Adding the Singleline-Option makes the . include \n-Characters.
// If there is no \n between {}, make it RegexOptions.No ne or
// do not add any option
Regex expression = new Regex(@"\{(?'gr oupname'.*?)\}" ,

^
-------------------------------------------------|
and again another "*" here !!!!!! That's it !

RegexOptions.Si ngleline);

// Find all matches for our regular expression in myString
MatchCollection matchCol = expression.Matc hes(myString);

// Iterate over the matches
foreach (Match foundOne in matchCol)
{
// Get the contents between the {} for the current match
// Will be "firstName" for the first match and "accountNam e"
// for the second match
string lookForMe = foundOne.Groups["groupname"].Value;

// Find the Value to replace lookForMe with
string replacement = this.findSomeDa taForKeyString( lookForMe);

// Finally, replace lookForMe by replacement in the source string
// We do this by a new regular expression which is built dynamically
// on the key we are processing...
myString = Regex.Replace(m yString, @"\{" + lookForMe + @\}",
replacement);
};

=============== =============== =============== =============== =============== =
Sorry, but I had no time to test it before I posted originally...

[Helen Voronina]

privet
"Boris" <bo*****@optonl ine.net> wrote in message
news:y5******** *************** @news4.srv.hcvl ny.cv.net...

lena test
"Michael Voss" <mi**********@l vrREMOVE.deCAPS > wrote in message
news:40876e39$1 @news...

"Michael Voss" <mi**********@l vrREMOVE.deCAPS > schrieb im Newsbeitrag
news:4083d5cb$1 @news...

Hi !

Dimitris Georgakopuolos wrote:
[...snip...]
> What I am trying to do is retrieve the values to do the
> replacement dynamically, therefore I do not know ahead of time in
> design time of the type of fields to look for; it could be
> {firstName} or {lastName} or 100 other fields that I don't want to
> hard code.
[...snip...]
> Would something like this work:
>
> return Regex.Replace(i nput,
> "{(?<name>} ",
> GetReplacement( "${name});
[...snip...]

Let's assume your string is "Hello {firstName}, Your account {accountName}

has been
updated."

As Du pointed out, the { and } will have to be escaped. Then, you are
looking for everything between \{ and \}, so the regular expression to

start

with would be "\{.\}" which would detect wether there is any occurrence of

a

pair of curly brackets in your string. Remember to put an @ in front

of

your

regular expression string, so C# knows the \ belong into your string

and are

not C#-escape-characters.
You will most likely want to find the shortest pair, as the expression

above

would find one occurence in our string, containing "firstName} , Your
account {accountName" between the pair of brackets. So we make the .

"lazy"

by adding a "?" behind. That makes "\{.?\}" for our improved

expression. This expression will match twice, with "firstname" and "accountnam e"
included between the two pairs of brackets.
Next, you want to remember the value that matches the regular

expression,

so

we crate a named group: "\{(?'groupname '.?)\}". This will find any

sequence

of characters (.?) between a pair of curly brackets (\{ and \}) and

store

it

in the group named "groupname" for each match. ?'groupname' names the

group

(you can use ?<groupname> instead) and everything else between the ()

makes

the expression, that will be stored in the group "groupname" .
Finally, we want to iterate over the matches:

=============== =============== =============== =============== =============== =

=====

string myString = "Hello {firstName}, Your account {accountName} has been updated.";

// Create a new regular expression
// Adding the Singleline-Option makes the . include \n-Characters.
// If there is no \n between {}, make it RegexOptions.No ne or
// do not add any option
Regex expression = new Regex(@"\{(?'gr oupname'.?)\}",
RegexOptions.Si ngleline);

// Find all matches for our regular expression in myString
MatchCollection matchCol = expression.Matc hes(myString);

// Iterate over the matches
foreach (Match foundOne in matchCol)
{
// Get the contents between the {} for the current match
// Will be "firstName" for the first match and "accountNam e"
// for the second match
string lookForMe = foundOne.Groups["groupname"].Value;

// Find the Value to replace lookForMe with
string replacement = this.findSomeDa taForKeyString( lookForMe);

// Finally, replace lookForMe by replacement in the source string
// We do this by a new regular expression which is built dynamically // on the key we are processing...
myString = Regex.Replace(m yString, @"\{" + lookForMe + @\}",
replacement);
};

=============== =============== =============== =============== =============== =

=====