Working With Numbers in PHP

By Stephen Bucaro

In PHP there are two main types of numbers, integers (numbers without a decimal point), and floats (numbers with a decimal point). You can declare an initialize a number as shown below.

$amount = 62;

Sometimes, when you first declare a number, you may not know its value. You can declare the variable, and initialize it later in the program flow as shown below.

$amount;
.
.
.
$amount = 62;

However, until you initialize the variable, PHP has no idea what data type you will be storing in it, so it sets its value to NULL. If you don't know a numbers value when you first declare it, it's better to set it to a default value like 0;

$amount = 0;
.
.
.
$amount = 62;

Unlike string variables, numbers are not placed within quotes. Digits within quotes would create a string variable. If you want to convert digits within quotes to a number, you cast it to an integer or float variable type. Shown below, digits in a string variable are cast to an integer before being used in a mathematical operation.

<?php

$a = "23";
$b = 32;
$c = $b + (integer) $a;
print $c;

?>

In many cases you don't need to cast a digits in a string to an integer or float because PHP will automatically convert a variable's type based upon the the context in which it's used. Shown below is an example of PHP automatic variable type conversion.

<?php

$a = "23";
$b = 32;
$c = $b + $a;
print $c;

?>

Arithmetic Operators

PHP includes the standard Arithmetic Operators.

The modulus operator performs division, except instead of returning the quotient, it returns the remainder. An example of modulus division is shown below.

$a = 50 % 6;
print $a;

The result of execution of the lines of code above would be a print of 2.

The increment operator increases the value by 1. the decrement operator decreases the value by one. An example of decrement is shown below.

$a = 50;
$a--;
print $a;

The result of execution of the lines of code above would be a print of 49.

When using arithmetic operators, you can also use the shortcut method shown below.

$a = 26;
$b = 14;
$a += $b;
print $a;

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