Homework: http://beginnerscpp.com/forums/index.php/topic,60.0.html



If Statements
If statements are used to determine the course that our program will run in, based off whether a condition evaluates to being true, or false. The statement of if has 2 parts. if and the condition that it’s checking (which can have many parts). A simple if statement might look something like this:

or they can be much more complex, like this

In the first example we are simply checking if a number is equal to the number 2. Once we determine that is true, we add 5 to the number. The second example is something you might see in a game development scenario. A user is goes to cast a spell, there needs to be checks made against current values, and those are passed over to our if statements. We need for ALL of those conditions to be true for the spell to be cast (the user needs enough intellect to understand the spell, they need both mana and health, and they cannot be stunned) if any of those are not true, it will be passed to the else if (and then evaluated for truth there) then passed to else if that is not true either.

If Statement Flowchart
Classically if statements were represented (in flowcharting) as diamond layed on its side, with lines coming from the edges diagonally to illustrate that there were two paths that can be taken from an if statement (symbolizing an if and an else). While this is technically correct, it does lead to some questions among beginners for instance the following is VALID code

In the example above you will notice that there is no “else” attached to this if. So the earlier example showing two distinct “branches” might not always be clearly represented in code. A way that I’ve seen some beginners cope with this confusion is by putting in Null else statements (else statements that are just placeholders) and I am against this for 2 reasons:

  1. It adds length to your code
  2. It adds no functionality to your code

Here’s an example of something a student sent me that was along those lines.

As you can see there is no functionality gained from this type of code.


Scope
Scope is essentially the “lifespan” of a variable. When a variable is declared within a specific scope it “dies” (is destroyed) with that scope. This is useful and dangerous at the same time. Scopes will become more important when we get into loops. Below is a short example showing a variable declared in a scope and being unavailable outside of the scope:

Boolean Comparison Operators

  • == (Equal to)
  • != (Not Equal To)
  • ! (Not (typically used with bool variables))
  • > (Greater Than)
  • < (Less than)
  • >= (Greater than / Equal to)
  • <= (Less Than / Equal to)
  • || (Or)
  • && (And)

Please note, the listing above is not a complete list of operators, but it will encompass the scope of what we will be learning in this course. There are other operators called “Bitwise operators” that you can read about if you choose, though you will likely not need to use them for quite some time.

Homework: http://beginnerscpp.com/forums/index.php/topic,61.0.html



Nested If Statements
Despite the title of this lesson, I did very little in the way of showing you nested if statements, and the reason why I opted to teach it this way was because I wanted to show that intelligent program design can get away from nesting. Sometimes nesting is unavoidable, and for those cases the following syntax remains true

The only thing that I can advise you on when it comes to nested if statements is that you should be EXTREMELY strict when it comes to your indenting. Furthermore, some people like to document their code to remind them which if statement they are in, however I find this type of commenting somewhat excessive. A comment here and there to remind us what something does, or what we’re testing is fine, but when you see something like this, it’s a bit excessive.

While I understand the intention of the person that made the comments, it actually adds to confusion over stating the implied usage on a single line like this:


Homework: No homework this lesson



Homework: http://beginnerscpp.com/forums/index.php/topic,62.0.html



Loops
The over-arching theory of loops is that sometimes you’re going to have a set of data, which will need to be iterated through and have actions performed on each member. You can use if statements to qualify what happens to each item, but the loop itself ensures that every item in a set is able to be iterated through.


While
While loops are the simplest of the loops that we’re going to be discussing. The syntax is exactly the same as an if statement.

One of the catches of using an while statement is that there needs to be some kind of a control in place or the loop will run endlessly. The most common way to see a while loop implemented for beginners is by incrementing a number. Here’s an example of how someone would do that:


Do_While loops
These loops weren’t actually covered in the videos, as I don’t feel that they are as important in theory as other loops. The purpose of a do_while loop is to ensure that something happens at least once. Typically, in programs you might see a do_while used to make a user enter a number within a certain range. For example:

As you can see, the above code took 3 lines, instead of 5. Let’s break down what exactly happened in this for loop. For loops are often broken into 4 basic parts:

  1. for statement –the literal use of the word “for” at the start of the line
  2. Initialization –This part allows you to create a variable or assign an existing variable a new value. An example of this is int counter = 0; as above.
  3. Conditional –This is the statement that must remain true (like a while) for the loop to continue running.
  4. Increment –This statement typically (although it doesn’t have to) brings your initialized variable closer to satisfying the conditional.

Here is one more example of for loops

It is strongly recommended that you review this lesson and familiarize yourself with loops in some depth, as the next lesson will be VERY challenging as it deals with nested loops.

Homework: http://beginnerscpp.com/forums/index.php/topic,63.0.html



Nested Loops
In this lesson I threw you guys straight into the deep end. The basic concept of nested loops is the same as a nested if statement, you have an inner loop that will complete all of it’s instructions every time through the outer loop (unless there is a break statement somewhere). Here’s an example:

As you can see in the example, the inner loop is running fully every time the outer loop iterates.