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Si vous êtes nouveau au PHP ou devez juste régénérer vos qualifications, c'est l'endroit à commencer. Cette série de cours d'instruction te donnera la connaissance de base que vous devrez créer un simple Site Web de PHP.
Le PHP est un langage de programmation r3fléchissant à l'origine conçu pour produire les pages Web dynamiques. [1] Le PHP est employé principalement dans le serveur-côté scripting, mais peut être employé d'une ligne de commande interface ou dans des applications graphiques autonomes. Des interfaces utilisateurs textuelles peuvent également être créées utilisant des ncurses.
PHP does not require (or support) explicit type definition in variable declaration; a variable's type is determined by the context in which the variable is used. That is to say, if a string value is assigned to variable $var, $var becomes a string. If an integer value is then assigned to $var, it becomes an integer.
An example of PHP's automatic type conversion is the addition operator '+'. If either operand is a float, then both operands are evaluated as floats, and the result will be a float. Otherwise, the operands will be interpreted as integers, and the result will also be an integer. Note that this does not change the types of the operands themselves; the only change is in how the operands are evaluated and what the type of the expression itself is.
<?php
$foo = "0"; // $foo is string (ASCII 48)
$foo += 2; // $foo is now an integer (2)
$foo = $foo + 1.3; // $foo is now a float (3.3)
$foo = 5 + "10 Little Piggies"; // $foo is integer (15)
$foo = 5 + "10 Small Pigs"; // $foo is integer (15)
?>
If the last two examples above seem odd, see String conversion to numbers.
To force a variable to be evaluated as a certain type, see the section on Type casting. To change the type of a variable, see the settype() function.
To test any of the examples in this section, use the var_dump() function.
Note: The behaviour of an automatic conversion to array is currently undefined.
Also, because PHP supports indexing into strings via offsets using the same syntax as array indexing, the following example holds true for all PHP versions:
See the section titled String access by character for more information.<?php
$a = 'car'; // $a is a string
$a[0] = 'b'; // $a is still a string
echo $a; // bar
?>
Type casting in PHP works much as it does in C: the name of the desired type is written in parentheses before the variable which is to be cast.
<?php
$foo = 10; // $foo is an integer
$bar = (boolean) $foo; // $bar is a boolean
?>
The casts allowed are:
(binary) casting and b prefix forward support was added in PHP 5.2.1
Note that tabs and spaces are allowed inside the parentheses, so the following are functionally equivalent:
<?php
$foo = (int) $bar;
$foo = ( int ) $bar;
?>
Casting literal strings and variables to binary strings:
<?php
$binary = (binary)$string;
$binary = b"binary string";
?>
Note: Instead of casting a variable to a string, it is also possible to enclose the variable in double quotes.
<?php
$foo = 10; // $foo is an integer
$str = "$foo"; // $str is a string
$fst = (string) $foo; // $fst is also a string
// This prints out that "they are the same"
if ($fst === $str) {
echo "they are the same";
}
?>
It may not be obvious exactly what will happen when casting between certain types. For more information, see these sections:
Des autres fonctions utiles :
types.comparisons | openssl.key-types | oci8.datatypes | language.types.type-juggling | language.types.string | language.types.resource | language.types.object | language.types.null | language.types.integer | language.types | language.types.float | language.types.boolean | language.types.array | language.pseudo-types | function.sqlite-fetch-column-types | function.soap-soapclient-gettypes | function.imagetypes | function.ifx-fieldtypes | about.prototypes |
Le PHP est une langue scripting d'usage universel employée couramment qui approprié particulièrement au développement de Web et peut être enfoncée dans le HTML. Si vous êtes nouveau au PHP et voulez avoir une certaine idée de la façon dont cela fonctionne, essayez le cours d'instruction d'introduction. Après ce, vérifiez le manuel en ligne, et l'exemple archivez les emplacements et certaines des autres ressources disponibles dans la section de liens.