Have a string look at a .txt file

I was wondering if anyone new how to have a string look at a .txt file instead typing out a long string.  As of right now I have a string with 34,000 addresses.  I would like it to just look at a .txt file instead of this long string.
 
[System.Web.Services.WebMethodAttribute(), System.Web.Script.Services.ScriptMethodAttribute()] public static string[] GetCompletionList(string prefixText, int count, string contextKey) { // Create array of addresses string[] addresses =  
 
At the end of this code then I have all 34000 addresses after this.
Thanks in advance :)
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