There are two types of number in PHP, namely, integers and floating point numbers, also known as “floats”.

Integer

An integer is a whole number like 1, 2 and 3 as well as -1, -2 and -3.

Floating Point Number

A floating point number is a number that has a decimal in it followed by a number of significant digits like 2.5 or -4.202.

Example code:

$var1 = 1; // Integer
$var2 = 2.5; // Floating Point Number

echo ((1 + 5 + $var1) * $var2) / 2 - 3; // Outputs: 5.75

Take note that in PHP, basic math rules like the parentheses and the order of operations between multiplication, division, addition and subtraction still applies.

Therefore…

• 1 + 5 + $var1 will be evaluated first which returns 7.
• 7 gets multiplied by the value of $var2 which returns 17.5.
• 17.5 gets divided by 2 which returns 8.75.
• 8.75 gets subtracted by 3 which would then return 5.75.

Incrementing/Decrementing a value

If you combine addition, subtraction, multiplication or division with the value assignment operator, you can either increment or decrement a number, for example:

$var1 = 1;
$var2 = 10;
$var3 = 2;
$var4 = 20;

echo $var1 += 2; // Outputs: 3
echo $var2 -= 5; // Outputs: 5
echo $var3 *= 2; // Outputs: 4
echo $var4 /= 2; // Outputs: 10

The above code can also be written in a much longer format like so:

$var1 = 1;
$var2 = 10;
$var3 = 2;
$var4 = 20;

echo $var1 = $var1 + 2; // Outputs: 3
echo $var2 = $var2 - 5; // Outputs: 5
echo $var3 = $var3 * 2; // Outputs: 4
echo $var4 = $var4 / 2; // Outputs: 10

If you only need to increment or decrement a number by 1, use ++ or -- instead, for example:

$var = 1;

$var++;
echo $var; // Outputs: 2

$var--;
echo $var; // Outputs: 1

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This is part 6 of the PHP Basics series.