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?> #最常用
2. <? ?> #最简单
3. <script language= "php" ></script> #最长的写法
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 (+)
For example: The first method: use. Connect
<?php
$a = "Ham";
$b = "Hamburg";
$c = "chicken Wings";
$AA = "n001";
$BB = "n002";
$CC = "n003";
$s = "<select>";
$s = $s. " <option value= ' ". $aa." > ". $a." </option> ";
$s = $s. " <option value= ' ". $bb." > ". $b." </option> ";
$s = $s. " <option value= ' ". $cc." > ". $c." </option> ";
$s = $s. " </select> ";
Echo $s;
?>
The second method:
<?php
$a = "China";
$b = "United States";
$c = "France";
$AA = "n001";
$BB = "n002";
$CC = "n003";
?>
<select>
<option value= "<?php echo $aa;? > "><?php echo $a;? ></option>
<option value= "<?php echo $bb;? > "><?php echo $b;? ></option>
<option value= "<?php echo $cc;? > "><?php echo $c;? ></option>
</select>
3. Comparison operators: Same as Java application
4. Logical operator:&& with available and | | Available or
PHP Beginner First Lesson