I am trying to replace string in a text file.
I use the following code:
string text = File.ReadAllText(@"c:\File1.txt");
text = text.Replace("play","123");
File.WriteAllText(@"c:\File1.txt", text);
It not only changes the word "play" to "123" but also change the word "display" to "dis123"
How to fix this problem?
You could take the advantage of "Regular expressions" here.
\b Matches the word boundary, This will solve your problem.
text = Regex.Replace(text, @"\bplay\b","123");
Read more about Regular expressions
You can use following snippets of code
var str = File.ReadAllText(@"c:\File1.txt");
var arr = str.Split(new[] { " " }, StringSplitOptions.RemoveEmptyEntries).ToList();
for (int i = 0; i < arr.Count; i++)
{
if (arr[i].StartsWith("play"))
{
arr[i] = arr[i].Replace("play", "123");
}
}
var res = string.Join(" ", arr);
File.WriteAllText(@"c:\File1.txt", result);
Also, this is case sensitive make sure this is what you want.
An alternative approach, and not regex based could be the following:
Define a few extension methods:
static class Exts
{
public static string GetLettersAndDigits(this string source)
{
return source.Where(char.IsLetterOrDigit)
.Aggregate(new StringBuilder(), (acc, x) => acc.Append(x))
.ToString();
}
public static string ReplaceWord(this string source, string word, string newWord)
{
return String.Join(" ", source
.Split(new string[] { " " }, StringSplitOptions.None)
.Select(x =>
{
var w = x.GetLettersAndDigits();
return w == word ? x.Replace(w, newWord) : x;
}));
}
}
Usage:
var input = File.ReadAllText(@"C:\test.txt");
var output = input.ReplaceWord("play", "123");
Console.WriteLine(input);
Console.WriteLine(output);
Prints:
This is a test: display play, play display -play !play - maybe it's working?
This is a test: display 123, 123 display -123 !123 - maybe it's working?
Try changing it to
text.Replace(" play ","123");
but this way it won't replace something like play. play, play;
Another technique you can use in this situation is to add more recognizable tokens into the text you wish to edit.. for example:
bla bla {PLAY} bla bla PLAY bla bla
would become
bla bla 123 bla bla PLAY bla bla
