The PHP If Statement

The if statement is necessary for most programming, thus it is important in PHP. Imagine that on January
1st you want to print out "Happy New Year!" at the top of your personal web page. With the use of PHP if statements you could have this process automated,
months in advance, occuring every year on January 1st.
This idea of planning for future
events is something you would never have had the opportunity of doing if you
had just stuck with HTML.

If Statement Example

The "Happy New Year" example would be a little difficult for you
to do right now, so let us instead start off with the basics of the if statement.
The PHP if statement tests to see if a value is true, and if it is a segment of
code will be executed. See the example below for the form of a PHP if statement.

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Did you get that we were comparing the variable $my_name with "someguy" to see if they
were equal? In PHP you use the double equal sign (==) to compare values.
Additionally, notice that because the if statement turned out to be true, the code segment
was executed, printing out "Your name is someguy!". Let's go a bit more in-depth into this example
to iron out the details.

• We first set the variable $my_name equal to "someguy".
• We next used a PHP if statement to check if the value contained in the
  variable $my_name was equal to "someguy"
• The comparison between $my_name and "someguy" was done with a double equal
  sign "==", not a single equals"="! A single equals is for assigning a value
  to a variable, while a double equals is for checking if things are equal.
• Translated into english the PHP statement ( $my_name == "someguy" ) is ( $my_name
  is equal to "someguy" ).
• $my_name is indeed equal to "someguy" so the echo statement is executed.

A False If Statement

Let us now see what happens when a PHP if statement is not true, in
other words, false. Say that we changed the above example to:

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If you work hard then you will succeed.

Else, if you do not work hard, then you will fail.

How does this translate into something useful for PHP developers?
Well consider this:

Someone comes to your website and you want to ask
this visitor her name if it is her first time coming to your site. With an if statement
this is easy. Simply have a conditional statement to check, "are
you visiting for the first time". If the condition is true, then take them to
the "Insert Your Name" page, else let her view the website as normal because you have already asked her for her name
in the past.

If/Else an Example

Using these conditional statements can add a new layers of "cool" to your
website. Here's the basic form of an if/else statement in PHP.

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This is a lot to digest in one sitting, so let us step through the
code, line by line.

• We first made a PHP variable called $number_three and set it equal to 3.
• In this example we compared a variable to
  an integer value. To do such a comparison we use "==", which in English means "Is Equal To".
• $number_three is indeed Equal To 3 and so this statement will evaluate to true.
• All code that is contained between the opening curly brace "{" that follows the if
  statement and the closing curly brace "}" will be executed when the if statement is true.
• The code contained within the else segment will not used.

Execute Else Code with False

On the other hand, if the if statement was false, then the code contained in the else segment would have been
executed. Note that the code within the if and else cannot both be executed, as
the if statement cannot evaluate to both true and false at one time! Here is what would happen
if we changed to $number_three to anything besides the number 3.

Display:

The variable was set to 421, which is not equal to 3 and the if statement was false. As you can see,
the code segment contained within the else was used in this case.