In the last chapter, we covered how to work with PHP's templating engine to write information to web pages, how to work with the interactive shell on the command line, and what variables are and their importance.

This chapter will follow on and build on these concepts. We will start by going over PHP's data types, followed by an introduction to arrays, what they are, how to use them, and the different types of arrays that are possible. Along the way, functions built into PHP that enable our code to execute specific actions will also be covered.

Values assigned to variables in PHP will be of a set data type. The following are the eight primitive data types:

• Strings – A simple text-based value
• Integers – Hold a numeric value, which is a whole number
• Floats – Hold a numeric value; can be a whole number or decimals
• Booleans – Hold a single value equating to true or false (1 or 0 is the numeric value of true and false)
• Arrays – Hold multiple values or other arrays within itself
• Objects – Hold a more complex data structure
• Resource – Holds a resource reference; for example, the reference of a function
• NULL – This value actually means there is no value

Let's now learn about the different types in more detail.

Integers

Integers are whole numbers. Typical examples of working with integers are when specifying quantities in a shopping cart, or as an ID when working with databases (Chapter 7, Data Persistence...

Scalar type declaration is either coercive (no need to be specified explicitly) or strict (type hinted strictly). By default, types are coercive.

Coercive means that PHP will coerce a number to an integer even if it's a string.

Take the following example. Here, we have a function called number that's been type hinted to only accept integers.

In this example, a string is being passed. When running PHP in coercive mode (this is on by default), this will work and print 1 to the screen:

<?php
function number(int $int)
{
    echo "the number is: $int";
}
number('1');

To facilitate strict mode, a single declare directive is placed at the top of the file containing the following:

declare(strict_types=1);

Now, run the example again in strict mode:

<?php
declare(strict_types=1);
function number(int $int)
{
    echo "the number is: $int";
}
number('1');

This...

An operator in PHP is something that takes one or more values or expressions and applies an operation to give a result that is either a value or another expression.

PHP divides the operators into the following groups:

• Arithmetic operators
• String operators
• Bitwise operators
• Assignment operators
• Comparison operators
• Increment/decrement operators
• Logical operators
• Array operators
• Conditional assignment operators

Arithmetic Operators

Arithmetic operators are used to perform math operations, for example, addition, subtraction, division, and multiplication.

There is the + operator. This takes different numbers separated by a + operator and will add the values together:

<?php echo 24 + 2; ?>

This will give us 26 as the output.

There is the - operator. This takes different numbers separated by a – operator and will subtract the values:

<?php echo 24 - 2; ?>

This will give us...

In this chapter, we learned about different PHP data types, including string, integer, float, and array. We also learned about different ways of declaring strings, including the heredoc and nowdoc syntaxes. We performed array operations in which we used indexed, associative, and multidimensional arrays and added and removed elements from arrays. We also performed type casting to change the types of variables.

In the next chapter, conditional logic will be covered. Conditionals introduce logic to your scripts and allow different actions to happen depending on different conditions; for instance, let's say you had a variable containing the word Pending and you want to show a statement only if the word is equal to Pending.

Understanding conditionals will unlock new ways of writing your code and allow further user interaction.