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iOS Swift Collections and Control Flow Introduction to Collections Reading and Modifying an Array

Posted by Giovanni Rinaldi
Giovanni Rinaldi
1,104 Points

Mutating an array

In my todo array, when I mutate the index value 4, I'm changing the fifth element..

So first my array is like that ["Finish collections course", "Buy grocieries", "Respond to emails", "Pick up dry cleaning", "Order book online"]

Then todo[4] = "Brush teeth"

["Finish collections course", "Buy grocieries", "Respond to emails", "Pick up dry cleaning", "Brush teeth"]

Sorry, but I'm a little bit confused, even if I have understood of it works! Thanks

Giovanni

1 Answer

Ian Billings
PLUS
Ian Billings
Courses Plus Student 7,494 Points
Ian Billings
Ian Billings
Courses Plus Student 7,494 Points

Hi Giovanni,

Its because Arrays always start at index 0, so "Finish collections course" would be referred to as todo[0]. If you tried to access todo[5] in your example you would throw an Array Index Out of Bounds error as that item doesn't actually exist.

Hope that makes sense.

Ian

Giovanni Rinaldi
Giovanni Rinaldi
1,104 Points

Absolutely yes! Thanks

Giovanni