Question

All I have is a file and a string to be searched inside it

Key
 Value1
 Value2
 Value3

Key1
 Value1

This is the structure of the file. Now, I search for a key and then read all values under it
until I find a newline (or simply a empty line)

I use this algorithm.

var valuelist = new List<string>();
using(var reader = new StreamReader(@"c:\test.txt"))
{
  String a;
  while( (a=reader.ReadLine())!=null)
 {
  if(!a.Equals("Key")) continue;
  while( a == reader.ReadLine() != null) //check whether end of file is not reached.
  {
    if(a.Length == 0) break; //a empty line is reached.hence comeout.
    valuelist.add(a);
  }
  } 
}

1. I am using “using” because it automatically disposes the “reader” object ? Is my approach right in this case ?

2. How Can I use a LINQ expression here in this context ?

I tried the following code

var all_lines = File.ReadAllLines(@"C:\test.txt");
 //How to retrieve "Values" for a given key using LINQ ?

Answer 1

1. The use of using in this context is very appropriate
2. To retrieve the values for a given key, you can use SkipWhile looking for the key by name, followed by TakeWhile looking for a blank line.

---

var list = new List<string>{
    "junk", " a", " b", "", "key", " c", " d", " e", "", "more", "f"
};
var vals = list.SkipWhile(s => s != "key").Skip(1).TakeWhile(s => s != "");
foreach (var s in vals) {
    Console.WriteLine(s);
}