Webmaster in a Nutshell, Second 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:
}                                     statements
else {                              endif;
  statements                       
}

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 need to execute only 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 the ...