PHP can work with 8 different types of data, which can be separated into 3 categories: scalar data types, compound data types and special data types.
Not that scary as it might sound. You already know half of that stuff. Of course if you attended math classes at school 🙂 … I did not 😉
Scalar data types
| Data Type | Example | Description |
| integer | 10, -74 | A whole number, can be either a positive or negative number |
| double/float | 128.56, -55.015 | A floating-point number |
| string | “Hello, world!” | A series of characters |
| boolean | true, false | Used for values that are either true or false. Most commonly used when working with conditional statements |
I hope this part is clear, maybe except for the Boolean data type, but don’t worry we’ll be working with that in our next tutorial. Now let’s see what compound data types have to offer.
Compound data types
| Data Type | Description |
| array | Stores multiple values that are indexed by numbers or strings |
| object | May contain multiple properties and methods |
What’s in common is that both of them can store multiple values and that is all we need to know for now.
Special data types
| Data Type | Description |
| resource | Used to access external resources, like database connection or file handle |
| null | Means the variable has not been assigned any value |
Not that widely used. I’ll try to think of some examples, but that’ll be much… much later 🙂
Loose typing in PHP
PHP is a loosely-typed language, which means you can change variable’s data at any time. For example, in Java once you declare a variable and its data type, you can’t change it – the variable must always contain only the data of the type we defined. Here’s some code example
int year = 2012;
year = 'text'; // this statement is wrong, cause we declared the variable as an integer
year – is the name of the variable we declare, int – is the data type assigned to it – integer. So the variable year can now only contain integer values, otherwise we’ll get an error. On the contrary in PHP we don’t need to think about that stuff:
$year = 2012;
$year = 'The end of the world is scheduled for '.$year;
echo $year;
// The result of echo would be: "The end of the world is scheduled for 2012"
How to check data type of the value
We can easily determine the data type using the gettype() function. We just need to pass a variable name into this function – gettype($var_name). Let’s play with some examples and check the result
$var;
echo gettype($var) . '
'; // displays "NULL" because we did not assign any value to the variable
$var = 58;
echo gettype($var) . '
'; // displays "integer"
$var = 12.52;
echo gettype($var) . '
'; // displays "double"
$var = "wassup";
echo gettype($var) . '
'; // displays "string"
You can also check if the variable contains a specific data type using the following functions:
| is_int( $var ) | Returns true if value is an integer, false otherwise |
| is_float( $var ) | Returns true if value is a float, false otherwise |
| is_string( $var ) | Returns true if value is a string, false otherwise |
| is_bool( $var ) | Returns true if value is a boolean, false otherwise |
| is_array( $var ) | Returns true if value is an array, false otherwise |
| is_object( $var ) | Returns true if value is an object, false otherwise |
| is_resource( $var ) | Returns true if value is a resource, false otherwise |
| is_null( $var ) | Returns true if value is NULL, false otherwise |
And here are some code examples for you to play with:
$var = 69;
echo is_int($var); // returns 1 which means TRUE
echo is_string($var); // The browser won't return anything to you, as the statement is FALSE
Using PHP conditional statements we could improve the browser output:
$var = 'Hello';
if ( is_string($var) ) {
echo "Yeah! It's a string";
}else{
echo 'The value of the variable is not string data type';
}
Using if…else statement we check if the variable is a string data type. If it’s true, then output ‘Yeah! It’s a string’ into the browser, otherwise output ‘The value of the variable is not string data type’.
Conclusions
You’ve learned all about PHP data types. You discovered different data types such as scalar, compound and special. We’ve also learned about PHP’s loose typing, and how to check the data type of a variable. Happy coding!
Questions? I’m waiting for them, guys and gals 🙂
