PHP if/else and switch

In this post we will:

  • Demonstrate how to use an if/else statement
  • Evaluate and justify when and demonstrate how to use a switch statement
  • Combine variables and operators to create more complex conditions and outcomes

What are conditional statements ?

  • Conditional or if/else statements test a variable or value against a set parameter
  • If a condition is met it is set to true and code is executed based on that outcome
  • If not another passage of code is executed

In Flow Form – How if/else works

if_else_flow

If/Else in practice

$instructorsName = "Toby";
$studentName = "Jocelyn";
    
    if($instructorsName == "Toby")
	{
	  echo "Hi $instructorsName - you are teaching PHP and MySQL today!";
	
	}
	else
	{
	  echo "Welcome to the PHP5 and MySQL course $studentName!";
	
	}

Output would be:

Hi Toby - you are teaching PHP and MySQL today!

Switch or Case Statement

So, what your a case statement be in flow form?

if_else_flow

Hang on – isn’t that the same as if/else?

What’s the point of that?

Why use switch?

  • Reduces lengthy and unwieldy if/else statements
  • Neater more legible code so easy to update and maintain
  • Less demand on the server
  • Greater control over error handling

Tip: Only use switch if you have more than four conditions

Switch in practice

    $weekday = "Tuesday";
    switch($weekday)
	{
	  case 'Sunday' : echo "Day off!";
	  break;
	  case 'Monday' : echo "Admin day";
	  break;
	  case 'Tuesday' : echo "Evening course";
	  break;
	  case 'Wednesday' : echo "Interactive Media year one";
	  break;
	  case 'Thursday' : echo "Interactive Media year two";
	  break;
	  case 'Friday' : echo "PHP Course HND Computer Science";
	  break;
	  case 'Saturday' : echo "Morning workshop";
	  break;
	  default : echo "The day you have put in is not valid!
"; exit(); } //echo "
This code is executed if none of the conditions of the switch statement have been met";

Try this task

Task: Create a simple if/else condition based on the previous examples in this lesson and also demonstrate how to use a switch statement. Test outcomes in a browser.

Build:

A pricing condition that adds a carriage fee £15 to any product less than a value of £100.

Also build a switch statement that adds varying degrees of delivery rates based on value.

In this post we have:

  • Demonstrated how to use an if/else statement
  • Evaluated and justified when and demonstrated how to use a switch statement
  • Combined variables and operators to create more complex conditions and outcomes
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