Sams Teach Yourself PHP in 24 Hours, Third Edition

Operators and Expressions

You can now assign data to variables, and you can even investigate and change the data type of a variable. A programming language isn’t very useful, though, unless you can manipulate the data you can store. Operators are symbols that enable you to use one or more values to produce a new value. A value that is operated on by an operator is referred to as an operand.

An operator is a symbol or series of symbols that, when used in conjunction with values, performs an action and usually produces a new value.

An operand is a value used in conjunction with an operator. There are usually two operands to one operator.

Let’s combine two operands with an operator to produce a new value:

4 + 5

4 and 5 are operands and are operated ...