Understading how inject works would take some time.
So please don't get frustrated if you don't understand it first time.
We are going to look at inject with various examples in coming lessons
so that it gets clearer with each lesson.
First let's take an example. Let's say that we have an array of items and we
want to add all the items. Here is how we can add all the items of the array.
In the above case we had to create a variable called total and we kept adding values to total to get
the final result. This works. However we can solve this problem much more easily using inject. First let's see what the code would look like if we are using inject.
Understanding inject
In order for us to understand what's going on we are going to add puts statement.
First let's change the same code to use do end style. Here is the modified code.
It's the same code with different style.
Here is how it works.
For the first time the value of result is zero because we are passing that value.
The value of element is 5.
Now we perform result + element.
So in this case we do 0 + 5.
"0 + 5" is 5. And this "5" becomes the new value for result.
For the second time the value of result is "5".
The value of element is 6.
Now we perform result + element.
So in this case we do 5 + 6.
"5 + 6" is 11. And this "11" becomes the new value for result.
For the third time the value of result is "11".
The value of element is 7.
Now we perform result + element.
So in this case we do 11 + 7.
"11 + 7" is 18. And this "18" becomes the new value for result.
For the fourth time the value of result is "18".
The value of element is 8.
Now we perform result + element.
So in this case we do 18 + 8.
"18 + 8" is 26. And this "26" becomes the new value for result.
We are done with all the elements so inject method will return
the final value of result which is 26.
Let's print each element value in inject.
So now we know that the second parameter in the block is the element which changes with each iteration.