PHP if statement

Control structures are the fundamental elements of PHP (and any other programming language). These structures allows you to controll the program / script flow. In PHP there are more control structures and we can split them into 2 categories.

• Conditional statements
• Iteration statements

In this description I will focus only on the if statement which is maybe the most important conditional statement.
You can use the if statement if you want to execute a set of code when a condition is true. It is very similar as in C. The syntax is the following:
if (condition) code to execute in case the condition is true;
Let's see a real example.

Code: 
  if ($userName == 'Peter') echo 'Hello Peter!';
 
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Notice that we used == in the condition and not =. This means that we want to check the equality og the left and right values and we don't want to assign a new value to the variable.

In this example there was only a one line statement to be executed if the condition is true. Of course you can use a complete code block. In this case you have to put all relevant code in a code block separated by { and } as follows:

Code: 
  if ($userName == 'Peter') {
     echo 'Hello Peter!';    
     echo 'Nice to see you again!'; 
  }
 
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In the previous step you have learnd the basic syntax of the if conditional statement. Now it's time to extend your knowledge a little bit. In PHP there are to check operators you can use as condition. In our previous example we used the == . However you can use the === as well. Yes, it is not a mis-spelling.

The difference between the 2 versions is the following:

• X == Y : True if X is equal to Y



• X === Y : True if X is equal to Y and X is the same type as Y.

So let's see a real life example:

Code: 
$X = 1; 
$Y = true;   

if ($X == $Y) {    
   echo "First test OK!"; 
} 

if ($X === $Y) {    
   echo "Second test OK!"; 
}

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In this example only the first test will pass as $X is an integer variable and $Y is a boolean. As the boolean true can be intrpreted as number value 1 so the first test will pass but as they have different types the second test will fail.