iOS Swift Collections and Control Flow Control Flow With Loops While and Repeat While

dakota ferrell
dakota ferrell
2,336 Points

Confused about the second part of while loops

I do not under stand what were doing or what this bit of code does

var index = 0 while index < todo.count

does this code talk to the line of code earlier with the todo array we did in a few videos back or is this something different? I am also confused about what a index does here?

is there any where I can get a second example of this?

1 Answer

Cory Harkins
Cory Harkins
16,471 Points


var index = 0

Our todo array (or ANY array) is "zero indexed" meaning we identify EACH value within an array with a numerical ID starting from 0.

var anyArray = [value with an index of 0, value with an index of 1, value with an index of 2]

So now, we want to print the values of our array or access all of them somehow.

We can use a while loop to do this. Let's say the array we're given has over 100+ values stored inside! Instead of counting or knowing before hand, we can use anyArray.count OR (todo.count) to find the total length of the array.

To loop through anything you need a range, because INDEXes in arrays start at 0, we make a variable to ID that index start point: ie; var index = 0 //the starting point for todo

THEN we need a max range, which will be the total length of the array


We can also store that into a variable as well for easy management

var lengthOfArray = todo.count

Now we have a base range (index = 0) and a max range (lengthOfArray) we can say

//while index is less than lengthOfArray { do something then increase the value of index }

while index < lengthOfArray { print(todo[index]) index = index + 1
//we don't want to print the same thing everytime, //so after the first index value is printed, //we need to increase the value of index to get the next value in the array }