If / Else / Elseif Statements

If / Else is a conditional statement where depending on the truthiness of a condition, different actions will be performed.

Note: The {} brackets are only needed if the condition has more than one action statement; however, it is best practice to include them regardless.

If Statement

<?php

  if (condition) {
    statement1;
    statement2;
  }

Note: You can nest as many statements in an "if" block as you'd like; you are not limited to the amount in the examples.

If/Else Statement

<?php

  if (condition) {
    statement1;
    statement2;
  } else {
    statement3;
    statement4;
  }

Note: The else statement is optional.

If/Elseif/Else Statement

<?php

  if (condition1) {
    statement1;
    statement2;
  } elseif (condition2) {
    statement3;
    statement4;
  } else {
    statement5;
  }

Note: elseif should always be written as one word.

Nested If/Else Statement

<?php

  if (condition1) {
      if (condition2) {
        statement1;
        statement2;
      } else {
        statement3;
        statement4;
      }
  } else {
      if (condition3) {
        statement5;
        statement6;
      } else {
        statement7;
        statement8;
      }
  }

Multiple Conditions

Multiple conditions can be used at once with the "or" (||), "xor", and "and" (&&) logical operators.

For instance:

<?php

  if (condition1 && condition2) {
    echo 'Both conditions are true!';
  } elseif (condition1 || condition2) {
    echo 'One condition is true!';
  } else (condition1 xor condition2) {
    echo 'One condition is true, and one condition is false!';
  }

Note: It's a good practice to wrap individual conditions in parens when you have more than one (it can improve readability).

Alternative If/Else Syntax

There is also an alternative syntax for control structures

  if (condition1):
    statement1;
  else:
    statement5;
  endif;

Ternary Operators

Ternary operators are basically single line if / else statements.

Suppose you need to display "Hello (user name)" if a user is logged in, and "Hello guest" if they're not logged in.

If / Else statement:

if($user == !NULL {
  $message = 'Hello '. $user; 
} else {
  $message = 'Hello guest';
}