Reading Contents of a File into a String Variable

We have a file (txt,doc,xml,xslt etc tested) and we wanted to read the content of that file into a string variable.

To do this I have following code section:
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using System.IO;

public string GetContentsOfFile(string URL)
{
if(string.Equals(URL,string.Empty))
throw new ArgumentNullException("URL not given");
StreamReader sr = new StreamReader(URL);
string retStr = string.Empty;
retStr = sr.ReadToEnd();
return retStr;
}
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This method will take URL of file as parameter and return a string with the contents of that file.

Enjoy...