converting String to Int failure [duplicate]-CodePudding

I've two variables number and number2 with String value, I want to convert those Strings to Int and add to each other,but the compiler returns error: Binary operator ' ' cannot be applied to two 'Int?' operands.

var n1 = "6"
var number = n1   "5"
Int(number)

var n2 = "3"
var number2 = n2   "5"
var finalNumber = Int(number2)   Int(number)
print(finalNumber)

I want summary of Int numbers and not strings. expected result: 19

CodePudding user response：

Because converting a String to an Int can be a failing operation, say converting A into an Int, you are using a failable initializer.

This means that you are getting Int? as a result. In your first example, you get a result of Optional(65) when printed. In playgrounds, the optional's value, of just 65, is shown instead.

The problem arrises that you can't add Int? together with the operator, only two Ints.

You can fix the problem by providing a default value if the conversion failed and the result is nil:

var finalNumber = Int(number2) ?? 0   (Int(number) ?? 0)