Front-end understanding of the brief PHP

Understanding PHP

PHP is an embedded language in HTML:

Using <?php?> to represent php delimiters, the statements written in this symbol are all PHP statements.

haha, today I bought a <?php echo 1+2+3;?>s I'm so happy!

PHP cannot be dragged directly into the browser locally because php must be running environment

Building the development environment

One-click installation package Phpnow

Http://www.onlinedown.net/soft/60958.htm

There are:

Apache

PHP Interpretation engine

Mysql

Language Core Overview Writing position

The written label is written in

<?php?>

No nesting! Can appear in any position!

PHP page extension must be . PHP, if it is . html , then it will be considered static page, do not parse.

Output Statement

PHP requires that all statements be semicolon-delimited. If you do not add a serious error, you will be an error, the following statement is not run.

The output statement in PHP is the current location of the page, not the console.

echo "XXXX";

ECHO is the output statement in PHP

Like what:

<?php echo 1+2*3;?>

Echo can also be used as a function to write the contents of the output in parentheses:

<?php Echo (1+2*3);?>

echo default does not wrap, if you want to wrap, you use . As a hyphen stitching the label.

Variable

The variable starts with the $ sign, followed by the name of the variable

Variable names must begin with a letter or underscore

Variable names cannot start with a number

variable names can contain only alphanumeric characters and underscores ( A-Z,0-9 and _)

variable names are case sensitive ($y and $Y are two different variables)

variables in PHP are also weakly variable types, no need to define what type, and what type to pass.

1<? PHP2        $a = 5; 3        $b = "AAA"; 4        $ctrue;        echo$a . "<br/>"; 7        echo$b . "<br/>"; 8        echo$c . "<br/>";    ? >

the scope of PHP is amazing.

PHP also does not have block-level scopes,if, for does not produce scopes.

function has scope limitations. A global variable, within a function, is not recognized by default. If you want to know a global variable inside a function, write the global keyword inside the function:

1    <?  PHP2        $a =;        function Fun  () {5            global$a; 6            echo$a; 7        }        (); Ten    ?>

operator

and JS the same, is not the same character, hyphen is .

Array

1<? PHP2    $aarray("East", "South", "West", "North", "Middle"); 3    echo$a[0];? >

The Echo statement cannot output the full picture of an array, you must use the print_r function.

$a Array ("East", "South", "West", "North", "Middle"); Print_r ($a);

The array length is to be used with the count () function:

echo count ($a);

Statement

the same as JS.

There are also if statements,if... Else , for , while , Do ... while , Switch all the same.

function

function Declaration Header elevation is JS -specific,PHP must first define the function, and then call the function.

function only () a method of invocation.

The function's argument, return value, and JS is the same.

Front-end understanding of the brief PHP