 Looking Adeptly at​ Programming Function Examples
Before looking at​ the​ different examples of​ programming functions,​ it​ is​ best to​ understand the​ purpose and definition of​ function .​
a​ function is​ the​ means by which someone who uses a​ program can execute a​ code block which has two purposes: to​ finish a​ certain task and to​ return values .​
Although functions are expected to​ return a​ certain value,​ it​ is​ not always that values are returned .​

A function is​ also considered as​ a​ procedure in​ some programming languages .​
On the​ other hand,​ functions are commonly known as​ any term that is​ being used in​ referring to​ names of​ code blocks .​
Take note that it​ is​ the​ C programming language which solely uses the​ keyword function .​
Functions accept restrictions,​ they also return values,​ and they are maintained on​ a​ separate location from the​ code of​ primary program .​
the​ C language uses main function as​ the​ point of​ entry to​ certain programs.
Functions can show up in​ a​ single or​ two locations .​
This is​ dependent on​ whether the​ function is​ single line or​ multi-line .​
Having a​ single line function means a​ value is​ returned after the​ performances of​ work (in a​ single line) while the​ multi-line function is​ broadened over different lines .​

Perhaps,​ the​ most common example of​ a​ programming function is​ a​ mathematical function .​
Log and tan are examples of​ mathematical functions .​
the​ other two known functions are string functions and the​ date functions .​

Simply defined,​ a​ programming function allows you to​ assign certain values where results can be calculated in​ a​ matter of​ seconds while saving yourself from the​ task of​ doing the​ 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 .​
One function declaration could resemble this:
function print_two_strings(\$var1,​ \$var2)
{
echo \$var1;
echo \n;
echo \$var2;
return NULL;
}
For these functions to​ be called,​ a​ value must be assigned to​ the​ parameters,​ hence:
Function call:
Print two strings (hi,​ guys);
The output should appear as:
hi
guys
One other good way to​ have active parameters is​ the​ use of​ PHP’s integral functions such as​ func get args,​ func get arg,​ and func num args functions .​
These functions are able to​ calculate arithmetic means of​ any values that are placed onto them and an​ output is​ derived .​
An example:
mean(35,​ 43,​ 3);
The output is​ then:
Mean: 27
A programming function is​ usually best when it​ returns some value or​ information .​
Functions do calculations,​ indeed,​ but it​ is​ also useful in​ indicating any errors that are encountered any function .​
To return an​ information from functions,​ you can use return () statement on​ the​ specified function .​

An example of​ script for PHP is​ the​ following:

The result is:
The result of​ 2+4+6 is​ 12.
Take note that {} statement ended the​ course of​ the​ function .​
If multiple variables are to​ be returned,​ a​ group of​ variables should be returned,​ not a​ single variable: An example:
function maths (\$input1,​ \$input2) {
\$total = (\$input1 + \$input2);
\$difference = (\$input1 - \$input2);
\$ret = array(tot=>\$total,​ diff=>\$difference);
return \$ret;
}
There are also ways of​ accessing functions without having to​ type a​ function name or​ {} syntax .​
This can be done in​ two ways: the​ call_user_func or​ the​ call_user_func_array .​
One complex example is​ the​ following:
\$one = One;
\$two = Two;
\$three = Three;
\$callback_func = my_function;
\$result = call_user_func_array(\$callback_func,​array(\$one,​\$two,​\$three));
echo \$result;
These equations may show as​ a​ bunch of​ gibberish letters and numbers but these symbols actually account to​ make a​ certain task easier .​
And that,​ for us,​ is​ the​ most important thing .​ 