Tutorial by Examples

Integers in PHP can be natively specified in base 2 (binary), base 8 (octal), base 10 (decimal), or base 16 (hexadecimal.) $my_decimal = 42; $my_binary = 0b101010; $my_octal = 052; $my_hexadecimal = 0x2a; echo ($my_binary + $my_octal) / 2; // Output is always in decimal: 42 Integers are 3...

A string in PHP is a series of single-byte characters (i.e. there is no native Unicode support) that can be specified in four ways: Single Quoted Displays things almost completely "as is". Variables and most escape sequences will not be interpreted. The exception is that to display a lit...

Boolean is a type, having two values, denoted as true or false. This code sets the value of $foo as true and $bar as false: $foo = true; $bar = false; true and false are not case sensitive, so TRUE and FALSE can be used as well, even FaLsE is possible. Using lower case is most common and recom...

$float = 0.123; For historical reasons "double" is returned by gettype() in case of a float, and not simply "float" Floats are floating point numbers, which allow more output precision than plain integers. Floats and integers can be used together due to PHP's loose casti...

Callables are anything which can be called as a callback. Things that can be termed a "callback" are as follows: Anonymous functions Standard PHP functions (note: not language constructs) Static Classes non-static Classes (using an alternate syntax) Specific Object...

PHP represents "no value" with the null keyword. It's somewhat similar to the null pointer in C-language and to the NULL value in SQL. Setting the variable to null: $nullvar = null; // directly function doSomething() {} // this function does not return anything $nullvar = doSomething...

There are two types of comparison: loose comparison with == and strict comparison with ===. Strict comparison ensures both the type and value of both sides of the operator are the same. // Loose comparisons var_dump(1 == 1); // true var_dump(1 == "1"); // true var_dump(1 == true); // t...

PHP will generally correctly guess the data type you intend to use from the context it's used in, however sometimes it is useful to manually force a type. This can be accomplished by prefixing the declaration with the name of the required type in parenthesis: $bool = true; var_dump($bool); // bool...

A resource is a special type of variable that references an external resource, such as a file, socket, stream, document, or connection. $file = fopen('/etc/passwd', 'r'); echo gettype($file); # Out: resource echo $file; # Out: Resource id #2 There are different (sub-)types of resource. Y...

PHP is a weakly-typed language. It does not require explicit declaration of data types. The context in which the variable is used determines its data type; conversion is done automatically: $a = "2"; // string $a = $a + 2; // integer (4) $a = $a + 0.5; // ...