Converting a binary string representation into binary array in C#

Stumbled across this question on StackOverflow the other day, definitely one for the interview! The question goes:

How do you convert a string such as “01110100011001010111001101110100” to a byte array then used File.WriteAllBytes such that the exact binary string is the binary of the file. In this case it would be the the text “test”.

Here’s my take on the answer :-)

var binaryStr = "01110100011001010111001101110100";

var byteArray = Enumerable.Range(0, int.MaxValue/8)
                          .Select(i => i*8)    // get the starting index of which char segment
                          .TakeWhile(i => i < binaryStr.Length)
                          .Select(i => binaryStr.Substring(i, 8)) // get the binary string segments
                          .Select(s => Convert.ToByte(s, 2)) // convert to byte
                          .ToArray();
File.WriteAllBytes("C:\temp\test.txt", byteArray);