Learn PHP(2) step by step - PHP types_PHP tutorial

1. About case
PHP’s built-in functions and structures are not case-sensitive.
For example:

Copy code The code is as follows:

echo("Hello PHP");
ECHO("Hello PHP");
Echo("Hello PHP");
?>

The three The effect is the same.
Others, user-defined class names and method names are also case-insensitive.
For example:

Copy code The code is as follows:

function Test()
{
echo ("Hello PHP");
}
Test();
TEST();
test();
?>

< ;/html>

But variables are case-sensitive.

2. Variables
I just want to mention one thing here. Anyone who has even a little contact with PHP will know that PHP declared variables start with the dollar sign ($).
In the previous example, we can also see this.
3. Type judgment function
In PHP, there are eight data types: integer, floating point, string, Boolean, array, object, NULL and resource. type.
There is a very important function when judging the type, the format is is_XX.
For example:

Copy code The code is as follows:

$intTest=1;
echo(is_int($intTest));
echo("
");
$stringTest="Test";
echo(is_string($stringTest));
echo("
");
echo(is_int($stringTest));
?>

http://www.bkjia.com/PHPjc/321311.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/321311.htmlTechArticle1. About case PHP’s built-in functions and structures are not case-sensitive. For example: Copy the code The code is as follows: html head titleHelloPHP/title /head body ?php echo("Hello PHP"); ECHO("H...