Examples of using the “if” command in PHP.
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.
