How to use PHP variables

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Variables in PHP start with the dollar sign $, followed by an identifier, which is a set of alphanumeric chars and the underscore _ char.

A variable can be assigned any type of value, like strings (defined using single or double quotes):

$name = 'Flavio';

$name = "Flavio";

Or numbers:

$age = 20;

or any other type that PHP allows, as we’ll later see.

Once a variable is assigned a value, for example a string, we can reassign it a different type of value, like a number:

$name = 3;

PHP won’t complain that now the type is different.

Variable names are case-sensitive. $name is different from $Name.

It’s not a hard rule, but generally variable names are written in camelCase format, like this: $brandOfCar or $ageOfDog. We keep the first letter lowercase, and the letters of the subsequent words uppercase.

I mentioned strings and numbers.

PHP has the following types:

  • bool boolean values (true/false)
  • int integer numbers (no decimals)
  • float floating-point numbers (decimals)
  • string strings
  • array arrays
  • object objects
  • null a value that means “no value assigned”

and a few other more advanced ones.

We can use the var_dump() built-in function to get the value of a variable

$name = 'Flavio';

var_dump($name);

The var_dump($name) instruction will print string(6) "Flavio" to the page, which tells us the variable is a string of 6 characters.

If we used this code:

$age = 20;

var_dump($age);

we’d have int(20) back, saying the value is 20 and it’s an integer.

var_dump() is one of the essential tools in your PHP debugging toolbelt.

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