How to remove more than one word from a string with regex ?

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I have a .txt file with a bunch of sentences and a .txt file with words I want to remove from the first file. I just started playing around regex and im not quite sure how to do it

What I have tried:

I have tried the following method which did not work for me.

C#

class Program
{
    static void Main(string[] args)
    {
        Program p = new Program();
        const string CFd = "..\\..\\Duomenys.txt";
        const string CFr = "..\\..\\Rezultatai.txt";
        const string Remove = "..\\..\\NorimiZodziai.txt";
        string lines = ReadingText(CFd);
        string removeW = ReadingText(Remove);                    //Words i want to remove from CFd file
        string replacedLines = Replaceing(lines, removeW);
        p.Printing(replacedLines,CFr);
    }

    static string ReadingText(string CFd)
    {
        string lines = File.ReadAllText(CFd, Encoding.GetEncoding(1257));
        return lines;
    }
    static string Replaceing(string lines, string removeW)
    {
        string pattern = @"\b"+removeW+"\b";
        string output = Regex.Replace(lines, pattern, "");
        return output;
    }
    void Printing (string replacedLines, string file)
    {
        using (StreamWriter writer = new StreamWriter(file))
        {
            writer.WriteLine(replacedLines);
        }
    }
}

Posted 17-Nov-18 1:15am

Mantukasx

Updated 17-Nov-18 4:34am

v2

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3 solutions

Solution 1

You don't need a regex for that: string.Replace will do the job just as well (and quicker, regex is a general purpose string processor, so it isn't as fast as a dedicated method.
String.Replace Method (System) | Microsoft Docs[^]

Posted 17-Nov-18 1:27am

OriginalGriff

Comments

Mantukasx 17-Nov-18 8:06am

If I want to remove words from different places, it doesn't remove anything, do i need to create an array of words i want to remove ?

OriginalGriff 17-Nov-18 8:21am

Do you want to try that again, this time without expecting me to be able to see your screen, access your HDD, or read your mind?

Mantukasx 17-Nov-18 8:58am

removeW has 3 words
class Program
{
static void Main(string[] args)
{
Program p = new Program();
Encoding.GetEncoding(1257);
const string CFd = "..\\..\\Duomenys.txt";
const string CFr = "..\\..\\Rezultatai.txt";
const string Remove = "..\\..\\NorimiZodziai.txt";
string lines = ReadingText(CFd);
string removeW = ReadingText(Remove); //Words i want to remove from CFd file
string replacedLines = Replaceing(lines, removeW);
p.Printing(replacedLines,CFr);
}

static string ReadingText(string CFd)
{
string lines = File.ReadAllText(CFd, Encoding.GetEncoding(1257));
return lines;
}

static string Replaceing(string lines, string removeW)
{
lines = lines.Replace(removeW, "");
return lines;
}
void Printing (string replacedLines, string file)
{
using (StreamWriter writer = new StreamWriter(file))
{
writer.WriteLine(replacedLines);
}
}
}

OriginalGriff 17-Nov-18 10:01am

If you are reading a bunch of words into a single string, you need to use string.Split to "break" the words you want to remove into single items. So if they are separated by space, then
string[] words = removeW.Split(' ');
Then use a loop to remove each of them in turn.

Solution 3

Thank you guys, i fixed it, however, after the words are removed, there are blank spaces and separators left, is there any possible way I can remove them ?

Posted 17-Nov-18 4:34am

Mantukasx

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Patrice T · Accepted Answer · 2018-11-17T03:27:00

Quote:
I have tried the following method which did not work for me.

It is a good idea to show examples of how it don't work.

Quote:
I have a .txt file with a bunch of sentences and a .txt file with words I want to remove from the first file.

Removing words is a little more complicated than what you did.

C#

string pattern = @"\b"+removeW+"\b";

In a sentence, a word is not necessary embedded between spaces, you can have , . ? ! and nothing if the word is first or last in string.
Another problem is that when you remove a word, you don't want to remove both spaces around the word, you need to keep 1 space.
So replacing by a space will already an improvement:

C#

string pattern = @"\b"+removeW+"\b";
string output = Regex.Replace(lines, pattern, " ");

You need to define what to do when a word is not between spaces, then deduce how it translate into code.
-----
Just a few interesting links to help building and debugging RegEx.
Here is a link to RegEx documentation:
perlre - perldoc.perl.org[^]
Here is links to tools to help build RegEx and debug them:
.NET Regex Tester - Regex Storm[^]
Expresso Regular Expression Tool[^]
RegExr: Learn, Build, & Test RegEx[^]
Online regex tester and debugger: PHP, PCRE, Python, Golang and JavaScript[^]
This one show you the RegEx as a nice graph which is really helpful to understand what is doing a RegEx:
Debuggex: Online visual regex tester. JavaScript, Python, and PCRE.[^]
This site also show the Regex in a nice graph but can't test what match the RegEx:
Regexper[^]