Handle null values in string variable

Hi  
i have an array    array[], it consists of number of decimal values like 5.7656876 including some null values.
I am using following to round off the value:
Label1.Text = double.parse(array[1]).ToString("#.#");

When the value in array comes out to be null it gives error : "input string was not in a correct format".
Can anybody tell . how to handle this null value.
As i have more than 300 distinct values in 300 Labels to handle,kindly give solution accordingly.
Thank you
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