Variables are exactly as their name suggests: variable. If a quantity is not a variable (cannot - or should not - change), then it is a constant (always the same).
To define a constant:
To define a variable in PHP, use a dollar sign ($). e.g. the variable which is the name of a customer being called from a database of many hundreds of customers could be defined as:
Variables can be defined (or redefined) at any point in a script. They can also be added together: for example, the full name of a customer could take the two parts of the name and combine them:
$fullname = $firstname.$lastname
A problem with this example is that the two name parts will have no space between them. The following example demonstrates how concatenation may be used to include non-variable elements, such as a space or a line break (<br />), into a variable:
The output of this code is
Fred McGurty, and
Variables are case sensitive and can include the underscore. These variable names:
\$_customer, are all valid and refer to different stored values.
Variable names may include numbers, but the first character after the dollar sign (\$) must be a letter or an underscore (_).
$_variable1 are valid, but
$1variable is not.
For clarity, a common technique to make variable names with multiple words more readable is to use the 'camelCase'. Instead of making a variable for 'my next great idea'
$mynextgreatidea, we use the camel case to make it more legible:
The equals sign (=) is used to assign a value to a variable. If the variable does not exist, the assignment also creates a new variable with this name. If the variable exists and has a previous value, the assignment replaces the previous value with the new value in the assignment statement. For example:
The output will be
The $oldVariable value (42) is replaced by the new value (21). In this example, a new variable is then created and given the same value as the old variable.
Now, examine the difference between these two
The outputs are:
The value stored in the newly created variable $newVariable is 21.
Content © Renewable-Media.com. All rights reserved. Created : October 14, 2015 Last updated :March 5, 2016
The most recent article is:
View this item in the topic:
and many more articles in the subject:
Physics is the science of the very small and the very large. Learn about Isaac Newton, who gave us the laws of motion and optics, and Albert Einstein, who explained the relativity of all things, as well as catch up on all the latest news about Physics, on ScienceLibrary.info.
Ernst Ulrich von Weizsäcker, b. 1939, is a prominent German scientist and politician. He is a popular author, with best-selling books like 'Factor Four', the update to the Club of Rome 'Limits to Growth', which explains how a sustainable economy requires reductions in consumption and increases in efficiency of this order of magnitude.
American hypocrisy is not the biggest hypocrisy in the world, but it is the biggest problem of the world.
Website © renewable-media.com | Designed by: Andrew Bone