c# - Why is the "IndexOutOfRangeException" occuring -

i following this tutorial on how allow program open files using "open with" method found in windows. however, program loads, crashes error "indexoutofrangeexception".

my code follows.

public static void main(string[] args)     {         if(args[0] != null)         {             application.enablevisualstyles();             application.setcompatibletextrenderingdefault(false);             application.run(new basic_word_processor());             basic_word_processor.instance.richtextboxprintctrl1.loadfile(@args.tostring());         }         else         {             application.enablevisualstyles();             application.setcompatibletextrenderingdefault(false);             application.run(new basic_word_processor());         } 

what causing exception occur?

this: args[0] because when args null trying access first element of array not exists.

so fix program have check if args not null:

if(args != null && args.length > 0) {             application.enablevisualstyles();             application.setcompatibletextrenderingdefault(false);             application.run(new basic_word_processor());             basic_word_processor.instance.richtextboxprintctrl1.loadfile(args[0].tostring()); } else {             application.enablevisualstyles();             application.setcompatibletextrenderingdefault(false);             application.run(new basic_word_processor()); }