Learning Swift™ Programming

Value Overflow and Underflow

If you try to fit too much into an Int that cannot handle it, you get an error. For example, the max for an Int32 is 2,147,483,647. You don’t have to do math to figure this out. You can figure it out like this:

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Int32.max // 2,147,483,647Int32.min // -2,147,483,647Int16.max // 32,767// etc...var a:Int32 = 2_147_483_649 // ERROR: integer literal overflows when stored into'Int32'

In this case, Int32 is not big enough to hold the number you tried to assign it. It is a little too large (the max is 2147483647 and you tried to use 2147483649), and you get an error. It isn’t always desirable or necessary to get an error. You can use value overflow and value underflow to fix this. When you reach ...