help with a system linq method - IEnumerable Where

Question

I have this line of code:
writer.Write(String.Join(Environment.NewLine, File.ReadAllLines(file).Where<string>((line) => line.ToLower().Contains(textToSearch.ToLower()))));
and the writer is a StreamWriter.

The function is to write to a file only the lines of another file which contains a specific string but i want to add to each line another string.
Example: the line matched is "c:\sura\da\k.txt" and i want to add "(from k.txt)" as example.

Is that possible?

Answer 1

Just add a select, which is the linq map function

writer.Write(String.Join(Environment.NewLine,   
         File.ReadAllLines(file)  
               .Where<string>(line => line..Contains(textToSearch, StringComparison.OrdinalIgnoreCase)  
                .Select( line => line + $” (from {textToSearch})”)   
)));  

Answer 2

Of course it is possible but would advise against a one-liner which maybe appealing but can't be debugged.

• Break the code down using conventional foreach or for.
• Rather than .ToLower use String.Contains(String, StringComparison) for .NET Core

Going this path is not elegant but is easy to debug and write unit test methods.