replace string and ignore underscore

Question

How to replace string and ignore underscore? the string structure should stay as is. I dont want remove the underscore. just replace the 'world' with 'sharp'. and only for whole words

string[] sentences =
{
    "Hello",
    "helloworld",
    "hello_world",
    "hello_world_"
};
foreach (string s in sentences)
{

    string pattern = String.Format(@"\b{0}\b", "world"); // whole case ignore underscore
    string result = Regex.Replace(s, pattern, "charp");

    Console.WriteLine(s + " = " + result);
}

output should be:

// Hello

// helloworld

// hello_charp

// hello_charp_

if you wnt to remove underscore you can you replace funtion like this s.Replace("_','') — Mehdi
– Mehdi, Commented Apr 21, 2016 at 12:39
structure should stay as is. I dont want remove the underscore — user6235593
– user6235593, Commented Apr 21, 2016 at 12:42

Dmitrii Bychenko · Accepted Answer · 2016-04-21 13:34:24Z

3

Something like this - in order to test for underscopes, but not include them into match use look ahead and look behind regex constructions.

  string[] sentences = new string[] {
     "Hello",
     "helloworld",
     "hello_world",
     "hello_world_",
     "hello, my world!", // My special test
     "my-world-to-be",   // ... and another one
     "worlds",           // ... and final one
  };

  String toFind = "world";
  String toReplace = "charp";

  // do to forget to escape (for arbitrary toFind String)
  string pattern = String.Format(@"(\b|(?<=_)){0}(\b|(?=_))", 
    Regex.Escape(toFind)); // whole word ignore underscore

  // Test:

  // Hello
  // helloworld
  // hello_charp
  // hello_charp_
  // hello, my charp!
  // my-charp-to-be
  // worlds

  foreach (String line in sentences)
    Console.WriteLine(Regex.Replace(line, pattern, toReplace));

In my solution I've assumed that you want to change whole words only which are separated by either word border ('\b') or underscope '_'.

edited Apr 21, 2016 at 13:34

answered Apr 21, 2016 at 12:42

Dmitrii Bychenko

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6 Comments

user6235593 Over a year ago

this doesnt check for whole word

Dmitrii Bychenko Over a year ago

@user6235593: Sorry, it does since word should be wrapped in either \b (word border) or _

user6235593 Over a year ago

oh btw cant use Linq functions since I use .net2

Dmitrii Bychenko Over a year ago

@user6235593: I've added a special test to demonstrate that whole word is checked

Dmitrii Bychenko Over a year ago

@user6235593: you're welcome, next time, please, provide more tests (for us not to guess what you're looking for), and specify restrictions (i.e. .Net 2.0 and alike)

|

Alfie Goodacre · Accepted Answer · 2016-04-21 12:58:22Z

1

You should use replace on _world

string[] sentences =
{
    "Hello",
    "helloworld",
    "hello_world",
    "hello_world_"
};
foreach (string s in sentences)
{

    string pattern = "_world";
    string result = s.Replace(pattern, "_charp");

    Console.WriteLine(s + " = " + result);
}

Just in case Dmitry is genuinely correct, it is worth also adding a second replace like so

    string pattern1 = "_world";
    string pattern2 = " world";
    string result = s.Replace(pattern1, "_charp").Replace(pattern2, " charp");

edited Apr 21, 2016 at 12:58

answered Apr 21, 2016 at 12:52

Alfie Goodacre

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4 Comments

Dmitrii Bychenko Over a year ago

Counter example: "hello world" should be changed into "hello charp"

Alfie Goodacre Over a year ago

@DmitryBychenko where is that stated? The OP never said that and none of their examples have spaces so why should that be necessary to handle?

Dmitrii Bychenko Over a year ago

technically it's not clearly stated, but in the question's code there's attempt to use regular expression \b{0}\b which indicates the attempt of whole word replacement

Dmitrii Bychenko Over a year ago

Another counter examples: "worlds" should be preserved intact when "my-world-to-be" should be changed (if you accept the hypothesis of whole word replacement).

NinjaDeveloper · Accepted Answer · 2016-04-21 12:43:26Z

0

using string replace function see this code example

using System;

class Program
{
    static void Main()
    {
    const string s = "Dot Net Perls is about Dot Net.";
    Console.WriteLine(s);

    // We must assign the result to a variable.
    // ... Every instance is replaced.
    string v = s.Replace("Net", "Basket");
    Console.WriteLine(v);
    }
}

Output

Dot Net Perls is about Dot Net. Dot Basket Perls is about Dot Basket.

answered Apr 21, 2016 at 12:43

NinjaDeveloper

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1 Comment

Dmitrii Bychenko Over a year ago

Counter example: "helloworld" expected to be preserved intact, but "hellocharp" is returned; you can't just Replace

sujith karivelil · Accepted Answer · 2016-04-21 12:54:00Z

0

in the comments, you specify that "world should be replace with sharp," then Why not be a simple replace using .Replace()

string wordToReplace="world";
string replaceWith="charp";
string[] sentences = { "Hello", "helloworld", "hello_world", "hello_world_" };
foreach (string  item in sentences)
{
    Console.WriteLine(item.Replace(wordToReplace,replaceWith));
}

edited Apr 21, 2016 at 12:54

answered Apr 21, 2016 at 12:44

sujith karivelil

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5 Comments

Dhara Over a year ago

will it do helloworld to helloSharp ?

sujith karivelil Over a year ago

@debin : sorry what you mean

Alfie Goodacre Over a year ago

@un-lucky they are saying that this will turn helloworld into hellosharp, when the OP only wants the word world preceded by an underscore to be changed to sharp

Dmitrii Bychenko Over a year ago

Counter example: "helloworld" expected to be preserved intact, but "hellocharp" is returned

user6235593 Over a year ago

Replace function doesnt check of whole word

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