Expressions, Operators, and Variable Assignment
We've already described simple examples of assignment, in which a variable is assigned the value of an expression using an equals sign. Most numeric assignments and expressions that work in other high-level languages also work in PHP. Here are some examples:
// Assign a value to a variable $var = 1; // Sum integers to produce an integer $var = 4 + 7; // Subtraction, multiplication, and division // that might have a result that is a float or // an integer, depending on the initial value of $var $var = (($var - 5) * 2) / 3; // These all add 1 to $var $var = $var + 1; $var += 1; $var++; // And these all subtract 1 from $var $var = $var - 1; $var -= 1; $var--; // Double a value $var = $var * 2; $var *= 2; // Halve a value $var = $var / 2; $var /= 2; // These work with float types too $var = 123.45 * 28.2;
There are many mathematical functions available in the math library of PHP for more complex tasks. We introduce some of these in Section 2.9.
String assignments and expressions are similar:
// Assign a string value to a variable $var = "test string"; // Concatenate two strings together // to produce "test string" $var = "test" . " string"; // Add a string to the end of another // to produce "test string" $var = "test"; $var = $var . " string"; // Here is a shortcut to add a string to // the end of another $var .= " test";