Doing math in php
$variable = value * value
$variable = value + value
$variable = value – value
$variable = value / value
Formatting Numbers
Rounding numbers – rounds values to specified decimal places. It can be number or variables. There is an option that allow users to round too the number of decimal places.
Example:
round (6.20); = 6
round (6.369, 2); = 6.37
$number = 694.2783;
round ($number); = 694
Number format – works like round but adds commas in the to numbers.
number_format (6.2243, 2); = 6.22
number_format (69, 2); = 69.00
number_format (123456789); = 123,456,789
Precedence - the order in which calculations are made.
8 – 4 / 2 = 6 and not 2 because division comes first.
To avoid this use ()
(8 – 4) /2 ) = 2
8 – (4 / 2 ) = 6
Incrementing and decrementing a number add or subtracts 1 value
$var++; or $var–; this will give the value +1 or -1 effect.
Creating random numbers
rand()
$n = rand();- this generate random number
$n = rand(0,100); – this generate random number 0 to 100
Other types are getrandmax() – get height random number
mt_rand() – it suppose to work better then rand and great for cryptography.
These notes are from PHP for the World Wide Web, Third Edition (Visual QuickStart Guide)
