If...
The first type of condition we will look at is
if, which has the following syntax:Again, the syntax is very close to ordinary English: If a condition is met, then execute something. Let's look at a simple example:
if ... else ...
The next type of condition will want to look at iselse , which may be presented in the following form:Again, the syntax is very close to ordinary English: if a condition is met execute something or else execute something else.
In lesson 4, you learned how to find the number of a month. In the following example, we will use the month number in an
if else condition to find out what season it is:show example
As you can see, this condition is not a particularly smart condition - it only works when it's March!
However, there are plenty of ways to improve the condition and make it more precise. Below are listed comparison operators that can be used in the condition:
== Equals
< Less than
> Greater than
<= Less than or equal to
>= Greater than or equal to
!= Not equal to
In addition, there are some logical operators:
&& And
|| Or
! Not
The operators can be used to develop more precise conditions, so now we can expand the above example to include all the spring months:
Let's take a closer look at the extended condition:
The condition can be translated into:
Smart, eh? Operators play a significant role in many different parts of PHP.
But it still only works with March, April and May. All other months are not yet covered by the condition. So let's try to develop the condition a little more.
if ... elseif ... else...
Usingelseif, we can expand the condition and make it work for all months:show example
To write conditions is all about thinking logically and being methodical. The example above is pretty straightforward, but conditions can get very complex.
switch ... case
Another way of writing conditions is to use theswitch method:This method is based on an expression and then lists different "answers" or "values" with related statements. The easiest way to explain the method is to show an example.
As you may remember from lesson 4, the function
date("w") returns the current weekday. This can be used in an example where we write the name of the day (instead of a number):show example
Often
switch can be a good alternative to if else
conditions. What you should use in a given situation depends on which
method you find easiest and most logical. Making your scripts logical
and clear can be a great challenge.In the next lesson, we will look at how you can add comments to your scripts to explain how they work. Good comments can be crucial if you or somebody else has to make changes in your codes at a later stage.
