PHP. Functions

PHP. Functions

https://www.w3schools.com/php/php_functions.asp

1. Function is called many times:

<?php

function a (){
echo "Hello";
}

a();

a();

# the value of the function is not returned
$a = a();

# nothing to print
echo $a ;

?>

2. The function is used recursivelly two times:

<?php

function f($a){

$b=$a*10;
return $b;

}

$c = f(10);
$d = f($c);

echo "$c $d";

?>

2a. Function with two parameters. One of then does not have default values, but another has.

<?php

function addNumbers( $a , $b = 2) {
return $a + $b;
}

echo addNumbers(1);

# fatal error
# echo addNumbers();

?>

3. Function, which has result an array:

<?php

function eee (){
return array ("jonas", "petras", "simas", "ona");
}

list ($a, $b, $c) = eee();

echo "$c ";// simas

?>

THE SCOPE OF VARIABLES

1. $a is not seen inside function:

<?php

$a = 2;

function test(){
echo "rezultatas $a ";
}

test();

?>

2. Inner variable $a is not seen outside:

<?php

$a =2 ;

function test(){
$a = 3;
echo "inner $a ";
}

test();
echo "$a "; //2

?>

3. return does not affect scope of view:

<?php

$a = 2;

function test(){
$a = 3;
return $a;
}

test();
echo "$a "; // 2

?>

4. Reference &:

<?php

$a = 2;

function reference(&$b){
$b = 10;
}

reference($a);

echo "$a "; // 10

?>

5. Global variables:

<?php

$a = "pirmas ";
$b = "antras";

function test(){

 global $a, $b;

 echo $a . " ";

 echo $b . " ";

 $b = $a . $b;

}

test();

echo "$b"; // It will print "pirmas antras"

?>

7. Global variables between functions:

<?php

$a = "";
$b = "";

function model(){

 global $a, $b;
 $a= 10;
 $b= 20;

}

function view(){

 global $a, $b;
 echo $a, $b;

}

model();
view()

?>

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PHP. Functions

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