Find and Replace for Multiline Text

Thiagarajan Alagarsamy

C#.NETFind TextMultiline SearchReplace TextSearch Text

6 Comments

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Farah Shaikh16y ago
Thanks for your code. I'm refering your code,Can we use doc file instead of text files Thanks in advance
ferdine silva17y ago
good solution for fine and replace multiline search in visual studio 2008
Hasibul Haque17y ago
Suppose I have a source string string strSource = "Hi this is sample test string. String that ends with . doesn't work. Strings makes problem. pleas help me i need your help very much."; If I use Replace ============= method then output string = strSource.Replace("string","ESTRINGS"); Then output will be "Hi this is sample test ESTRINGS. ESTRINGS that ends with . doesn't work. ESTRINGSs makes problem. pleas help me i need your help very much."; If you watch underline text then it makes problem it replace all the thing. I want to replace specific thing. Thats why I have used System.Text.Regulerexpression Using RegulerExpression ====================== output = Regex.Replace(source,"\\bstring\\b", "ESTRINGS" ) Then it returns "Hi this is sample test ESTRINGS. ESTRINGS that ends with . doesn't work. strings makes problem. pleas help me i need your help very much."; which recovers previous problem. But in this method i have a problem If i used output = Regex.Replace(source,"\\bstring.\\b", "ESTRINGS" ) then No replace is performed. So how i can Replace this ?? hope you will help me...
- Thiagarajan Alagarsamy17y ago
  Hi Hasibul, "." character has special meaning in Regular Expressions. It means it matches any single character. An example of this is the regular expression s.t would match the strings sat, sit, but not sight. If you want the RegEx to consider "." as a character instead of the special meaning, you can use escape character (backslash) in front of the character to remove the special meaning. In your case, you can try using //bstring//. Please let me know if this helps. Thanks, Thiagarajan A
raju tyagi17y ago
hi , i m raju I want the find & replace coding. I am making the notepad
- Bechir Bejaoui17y ago
  You can use System.Text.StringBuilder.Replace("old string","new string ");

Many of us would have used "Find and Replace" option available in our IDE and in many of the text editors. This functionality finds a single line of text given and replaces with the given text in the current document as well as in the files under a given folder. But how would you find and replace a multiline text? In this article I have tried to explain that.

The project included in this article has a simple file reading operation. For the beginners first let me explain how to read files. You can skip this section if you are familiar with file operations.

File Operations

The first step is to include the System.IO namespace in the using directive.

using System.IO;

System.IO namespace has DirectoryInfo class which is used for typical operations such as copying, moving, renaming, creating, deleting and enumerating through directories and sub-directories. Files under a specific directory can be found using this class.

The following statement instantiates DirectoryInfo class with a folder path from the text box.

DirectoryInfo DI= new DirectoryInfo(txtFolder.Text);

To get the file information we use the following statement.

foreach(FileInfo FI in DI.GetFiles())

The GetFiles method of the DirectoryInfo class, returns an array of FileInfo object. The FileInfo class like DirectoryInfo has operations for reading, copying, moving, renaming, creating and deleting files.

Now we use a StreamReader object to read the file.

StreamReader SR= new StreamReader(FI.OpenRead());

We use the following statement to read a line and assign it to a string variable.

s=SR.ReadLine();

Search Operation

We read each line and store it in a temporary variable appending a new line character ("\r\n") at the end of the line.

This will differentiate each line for searching multiline text.

temp=temp+s+"\r\n";

Now to search the string we use IndexOf() method in the temporary variable with the search text as parameter.

pos=temp.IndexOf(txtFind.Text);

The above statement returns the position of the search text.

We use a list box to record the number of files that matches the search text and the occurence of the first position.

Replace Operation

For the replace functionality, we use Replace() method in the temporary variable with search string and string to replace as arguments.

temp=temp.Replace(txtFind.Text,txtReplace.Text);

To reflect this change in the actual file, we need to write it to the file. So we use StreamWriter object to write to the file.

StreamWriter SW= new StreamWriter(FI.OpenWrite());
SW.Write(temp);
SW.Close();

Source code is included at the top section of this article. The code is self explanatory.

Thats all folks!!!