Basic syntax for PHP

PHP: A powerful scripting language

B/s:brower: Browser server: Server

C/S: Client: Clients Server: Servers

I. Markup for PHP embedded pages

1. <?php?>
2. <?>
3. <script language= "PHP" ></script>

Two: PHP's comment syntax

1.//Single-line comment
2. #单行注释
3./* * * Multi-line Comment

Three: The output syntax of PHP

1.echo can output multiple strings
2.print can only output one string
3.print_r (); You can output string numbers, and you can output the contents of arrays and arrays
4.var_dump (); Types of output variables

Four: Data types

PHP is a weakly typed language

Strongly typed languages:
1. Integral type: int
2. Float Type: float,double,decmial
3. Character type Char
4. String Type: String
5. Date and Time type: datetime
Model 6.bool
Model 7.object
int a = 5;
string s = "";


Weakly typed languages:
var a = 5; Js

V: Variable definition

Variables must start with $, variable names can be customized, but try not to use keywords
For example: $str = "Hello";

Variable variable:
$hello = "Hello";
$test = "Hello";
echo $ $test;

Isset ($hello): Determining whether a variable is defined
Unset ($hello); clear variables
Empty ($hello); Determines whether the variable is empty, null string, and 0 are empty

Take the address, with the & symbol: Example:
$s = "hello";
$str = & $s;
$STR = "World";
Echo $s;

VI: Conversion of data types
Get type:
GetType ($a);
Determine if there is some type of data:
Is_ type name ($a);

1. (int) $a;
2.settype ($a, int);

Seven: operator expressions

1. Mathematical operators
/except: integer In addition to integer result is decimal (reason: PHP is a weakly typed language)

2. String: Stitching a string with a dot (.) is not used (+)

3. Comparison operators: Same

4. Logical operator:&& with available and | | Available or

Basic syntax for PHP