Programming
Functions – Basic Concepts
Before
looking at different examples of programming
functions, it’s better to understand the purpose and
definition of
function.
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A function in programming is
the means by which someone who designs or uses a program can execute a
block of
code which has two purposes: to finish a certain routine
or task and/or
to
return processed values.
A function is also
considered as a procedure
in some
programming languages. |
On
the other
hand, software functions are commonly known as any term that is being
used in
referring to names of code blocks. Functions accept restrictions, they
also
return values, and they usually are maintained on a separate location
from the
code of the
main program.
Perhaps, the most
common example of a programming
function is a mathematical
function.
‘log’
(for logartithm) and ‘tan’ (for tangent) are examples of mathematical
functions. There
are other functions to
work with ‘strings’ (alphanumerical characters) and time functions,
just to
name a few...
Simply expressed, a programming function allows you to
assign certain values where results can be calculated in a matter of
seconds |
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(usally
much less) while saving you from the task of doing the operations or
computations
manually.
On the declaration or
calling of a function which has two
or more parameters, the use of comma is needed to separate the
different
parameters. Particularly
in Matlab (or
in any other of its similar open
source counterparts, such as Scilab,
GNU-Octave, FreeMat... etc.) one function declaration could
resemble
this:
function [cm,
kg] = anglo2metric(in, lb)
cm = in
* 2.54;
kg = lb
* 0.45359237;
You send parameters
‘in’ (for inches) and ‘lb’ (for
pounds) to function ‘anglo2metric’. This function processes those
numbers and
return two values, in ‘cm’ (for centimeters) and ‘kg’ (for kilograms).
You can choose
the names of the input parameters and of the output values.
A coded function is
used to return some value or
information. Functions
(made by you or
built-in) do calculations, sure, but they’re also useful to indicate
some
errors that they encounter, let’s say for debugging purposes.
On this page we’re not
talking about any specific
programming language. Functions do exist in every computer language.
An example of script
for PHP is the following:
<?php
function add_numbers($var1 = 0, $var2 = 0, $var3 = 0)
{
$var4
= $var1 +
$var2 + $var3;
return
$var4;
}
$sum =
add_numbers(3,4,6)
echo “The result of 3 + 4 + 6 is {$sum}
?>
After execution, you
get:
The result of 3 + 4 +
6 is 13
Note that sometimes you need special characters (such as
‘{’ and ‘}’) to define your start/end of youre function, or the
reserved words
‘return’ or ‘endfunction’ to end
that portion of code.
These sentences may look
like a bunch of strange letters
and numbers but these symbols actually account to make a certain task
easier. And that,
for the moment, is the
most important thing.
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