Branching Statements

Branching statements (conditionals) enable a PHP script to select from among different branches (or blocks of code) in the program's execution.

Contents

The if statement

if (conditional expression) {  // If this expression evaluates to TRUE
   block of code;              // This block of code is executed; otherwise it is skipped
}
  • The (optional) else clause is executed when the conditional expression is FALSE.
if (conditional expression) {  // If this expression evaluates to TRUE
   block of code;              // This block of code is executed.
} 
else {
   another block of code;      // This block is executed if the expression is FALSE
}
  • Examples
$n = 55;
if ($n % 5 == 0) {
    echo "$n is divisible by 5";
} 
else {
    echo "$n is NOT divisible by 5";
}

if ($n % 10 == 5 && $n * 2 < 100) {
    echo "$n is divisible by 5 and its value doubled is less than 100 ";
} 
else {
    echo "Either $n is NOT divisible by 5 or its value doubled is not less than 100";
}

The elseif statement

The elseif statement lets you combine a number of unique alternatives into a single statement.

if ($username == "Admin"){
   echo "Welcome to the admin page";
}
elseif ($username == "Guest") {
   echo "Welcome. Have a look around";
} 
else {
   echo "Welcome back, $username";
}

The ternary ? operator

The ? operator is like an if statement except it returns a value from one of the two expressions depending on the value of its conditional:

 (conditional expression) ? return_if_true : return if false ;

$logged_in = TRUE;
$user = "Admin";
$banner = ($logged_in==TRUE) ? "Welcome back, $user!" : "Please login";
echo $banner;

The switch statement

The switch statement provides a multiway selection structure. Depending on the value of a variable, one of several branches is selected. It requires the use of the break statement.

switch ($username) {
   case "Admin": 
      echo "Welcome to the Admin page";
      break;
   case "Guest":
      echo "Welcome. Have a look around";
      break;
   default:
      echo "Welcome back, $username";
}

Exercise

Write a switch statement that adds, subtracts, multiplies, or divides x using the action variable. Click here for a solution.