C# Array to String Function (and back)

Hi coders, I need a very small c# function that takes a double[] array and converts it to a string (so I can pass it as a string variable - which is required for my purposes). The array is variable in size but will be approximately 150 elements in length. The elements all range in value from 0 to 30, and the catch is, a lot of the elements of the array are 0 (zero), so I am hoping to compress the final string as much as possible. Just make some data up The I need to be able to take that string and reverse it back to the double[] array. I'll grant a bonus if this is done asap. All questions are welcome! Thanks, Brett