Function creating, calling,PHP built-in function วิชา PHP

1. PHP

2. Function creating, calling,
PHP built-in function

3. Function
• Sub routine.
• A function is a block of code that you can call
throughout your PHP script. Functions are
often used for common functionalities that
can occur in your PHP program. For an
example think that you write a program that
relates to seasonal offers. In many occasions,
you would need to know the final price after a
discount was given. You can define a function
for this as below.

4. Creating function
function functionName($param1, $param2)
{
code to be executed;
code to be executed;
return anyValue;
}
Optionally, datas to be
passed into function. It
can be unlimited
number of datas.
Optionally return
value back to the
one who call the
function.

5. Creating function- Example
function print_hello()
{
print “Hello”;
}
A function that does not require any external
datas to process. It done the job by just print
word “Hello” to the screen. It return nothing
to the place it is being called.

6. Creating function- Example
function transfer($account_a, $account_b, $amount)
{
$account_a = $account_a - $amount;
$account_b = $account_b + $amount;
return $account_b;
}
• A function that takes 3 external datas (parameters)
to process. The function subtract $amount from
$account_a then $amount add to $account_b. Finally
return the result to the place it is being called.

7. Calling function
/*** Functions declaration ***/
function print_hello()
{
print “Hello”;
}
function transfer($account_a, $account_b, $amount)
{
$account_a = $account_a - $amount;
$account_b = $account_b + $amount;
return $account_b;
}
/*** Using functions we just declare above here ***/
print_hello();
print transfer(500, 200, 50);

8. PHP Built-in Functions
in common use

9. Useful PHP Built-in functions
• (Q) What is PHP built-in functions?
• (A) Instant, Ready to use functions provided
by PHP producer. No need to create by
ourself.

10. phpinfo()
Benefit: Print PHP information, configuration,
settings out to screen
Example:
phpinfo();

11. Function for String :: trim()
Benefit: Remove whitespace from both ends of
string
Example:
$str = ‘ Hello There ’;
$new_str = trim($str);
print $new_str;
Result:
Hello There

12. Function for String :: explode()
Benefit: Explode string into array
$pizza = "piece1 piece2 piece3 piece4 piece5 piece6";
$pieces = explode(" ", $pizza);
print $pieces[0]; // piece1
print $pieces[1]; // piece2

13. Function for String :: implode()
Benefit: Implode array into string
$array = array('lastname', 'email', 'phone');
$comma_separated = implode(",", $array);
print $comma_separated; // lastname,email,phone

14. Function for String :: strlen()
Benefit: Get string’s length (How many characters inside
the string)
$str = 'abcdef';
print strlen($str); // 6
$str = ' ab cd ';
print strlen($str); // 7

15. Function for String :: strstr()
Benefit: Find the first occurrence in the string
case-sensitive stristr() will be used for incase-
sensitive.
$email = 'name@example.com';
$domain = strstr($email, '@');
echo $domain; // prints @example.com

16. Function for Array :: count()
Benefit: Count all elements in array
$a = array();
$a[0] = 1;
$a[1] = 3;
$a[2] = 5;
$result = count($a);
print $result; // output 3
$food = array('fruits' => array('orange', 'banana', 'apple'),
'veggie' => array('carrot', 'collard', 'pea'));
// recursive count
print count($food, COUNT_RECURSIVE); // output 8
// normal count
print count($food); // output 2

17. Function for Array :: array_rand()
Benefit: Pick one or more random entries out of an array
$input = array("Neo", "Morpheus", "Trinity", "Cypher", "Tank");
$rand_keys = array_rand($input, 2);
print $rand_keys;

18. Function for Array :: print_r()
Benefit: Print structure of array.
Note that we should wrap it with
<pre></pre> for readability.
$a = array ('a' => 'apple',
'b' => 'banana',
'c' => array ('x', 'y', 'z'));
print “<pre>”;
print_r($a);
print “<pre>”;
/****
<pre>
Array
(
[a] => apple
[b] => banana
[c] => Array
(
[0] => x
[1] => y
[2] => z
)
)
</pre>
****/