PHP if statement syntax

Contributed by qmchenry December 27, 2003  
Tagged: PHP programming

The simplest if statement executes command(s) if a condition evaluates as true:

if ($var > 0 ) {
// code here run if $var is positive
echo "Square root is: ".sqrt($var);
}

An optional else block can be added to execute code if the test condition evaluates as false. Multiple lines of code must be enclosed within { braces } while a single statement can be used in an if statement without braces.

if ($var >= 0 )
echo "Square root is: ".sqrt($var);
else {
$negvar = -1*$var;
echo "Square root is: ".sqrt($var)."i";
}

If statements can be nested:

if ($var < 10)
echo "var is less than 10";
elseif ($var < 20)
echo "var is between 10 and 20";
elseif ($var < 30)
echo "var is between 20 and 30";
else
echo "var is greater than 30";


A compact (if cryptic) shorthand is useful:

echo "var is ".($var < 0 ? "negative" : "positive");

is equivalent to:

echo "var is ";
if ($var < 0)
echo "negative";
else
echo "positive";


The shorthand can be considered (expression ? true_value : false_value) where ‘expression’ is evaluated and, if true, the ‘true_value’ is returned, otherwise the ‘false_value’ is returned.