Webmaster in a Nutshell, Third Edition

Control Structures

The control structures in PHP are very similar to those used by the C language. Control structures are used to control the logical flow through a PHP script. PHP’s control structures have two syntaxes that can be used interchangeably. The first form uses C-style curly braces to enclose statement blocks, while the second style uses a more verbose syntax that includes explicit ending statements. The first style is preferable when the control structure is completely within a PHP code block. The second style is useful when the construct spans a large section of intermixed code and HTML. The two styles are completely interchangeable, however, so it is really a matter of personal preference which one you use.

if

The if statement is a standard conditional found in most languages. Here are the two syntaxes for the if statement:

if(expr) {              if(expr):
  statements            
                  statements
} elseif(expr) {      elseif(expr):
  statements          
                    statements
} else {               else:
  statements           
                  statements
}                        endif;

The if statement causes particular code to be executed if the expression it acts on is true. With the first form, you can omit the braces if you only need to execute a single statement.

switch

The switch statement can be used in place of a lengthy if statement. Here are the two syntaxes for switch:

switch(expr) {         switch(expr):
  case expr:               case expr:
    statements              
                  statements
    break;                    break;
  default:                  default:
    statements              
                  statements
    break;                    break;
}                            endswitch;

The expression for each case statement is compared against ...