Loops n Strings n Things - Part 2

Released 17/9-2002

Written by VerticalE

 In the first part of the article, we examined and explained the code inside the loop codeblock as shown below:

Now we're gonna take a look at the really scary stuff outside of it. We'll start with the following declaration:

int myAge = 8;

As you probarbly know, we are declaring an integer value with the name myAge and assigning it the value 8 (to satisfy our younger readers). Next, we set up out loop. In this case, we are using a for-loop. Their setup can basically be divided into three sections, each separated with a semicolon.
 

for( int i = 0 ; i<10 ; i = i + 1 )

<- starting a for-loop <-- part 1 <-- separator <-- part 2 <-- separator <-- part 3 <-- end of the for-loop setup

Part 1
Here we are setting up the "counter". Just think about it; you cannot count unless you use a number. Even when you count out loud with your voice, you are in a way using a type of value that you are either incrementing or decrementing. In our loop we call the counter variable "i", say that its an integer value and set it at a starting value of 0. When we have told the for-loop what variable we want to increment, we move on to the next part with the semicolon as a separator.

Part 2
This part tells the for-loop how long it will loop. In this case, it will loop for as long as the value of i is smaller than 10. Here are a few other examples of what could be written in this part:

i>10 - i is bigger than 10 - would cause the application to just jump over the whole loop, since i is never more than 10.
i!=10 - i is not 10 - would cause the loop to go on and on as long as i is not 10. Would have the same impact as i<10.
i==10 - i is 10 - the loop wouldnt run at all, and the application would just jump over the whole codeblock, disregarding it. Again, we separate this part from the next with a semicolon.

Part 3
Here we increment the value (add 1) each time the loop runs. This means that when the codeblock has been run once, the value is incremented - NOT before it has run. Hence, the value of i the first time the loop runs is still 0, until it has finished once, and start again. If you remember from the first part of this article, we shortened the code down to a smaller statement. This can be done here as well, using the ++ incremention operator. This time, we dont need to end this statement with a semicolon, since it is the last part of the for-loop setup. Our updated code now looks like this:
 

In the next part of this article series, will look at a new type of loop; the while-loop.