Basics of Getting Started with PHP - Grammar_PHP Tutorial-PHP Tutorial-php.cn

Basics of Getting Started with PHP - Grammar_PHP Tutorial

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Release： 2016-07-13 17:13:52

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This is a simple introduction to PHP syntax. Friends in need can refer to it.

1. Double quotation marks and single quotation marks
Variables can be executed in double quotes, but constants using define are not executable in both single and double quotes:

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代码如下

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$var = 'sofish';
echo 'im $var'; // => 'im $var'
echo "im $var"; // => 'im sofish'

define('NAME', 'sofish');
echo 'im NAME'; // => 'im NAME'
echo 'im ' . NAME; // => 'im sofish'

$var = 'sofish';

echo 'im $var'; // => 'im $var'

echo "im $var"; // => 'im sofish'

define('NAME', 'sofish');

echo 'im NAME'; // => 'im NAME'

代码如下

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// JS 中我们用 var name = 'sofish';
$name = 'sofish';

// JS 中我们用 var NAME = sofish; 而且是可以改变的
define('NAME', 'sofish');

// 在这里会报错，因为 NAME 已经被定义，而 JS 可以随时改变
define('NAME', 'error');

echo 'im ' . NAME; // => 'im sofish'

No variables can be rendered within quotes in JS.

2. Definition of variables

Use the $ sign instead of the var keyword; have real constants, use the define function, and once defined, can be changed.

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// In JS we use var name = 'sofish';

代码如下	复制代码
$arr = array('name' => 'sofish', 'age' => '25', 'gender' => 'male');

$name = 'sofish';

// In JS we use var NAME = sofish; and it can be changed

define('NAME', 'sofish');

代码如下	复制代码
$arr = array('1' => 'sofish', '25', 'male') $arr = array('1' => 'sofish', '2' => '25', '3' => 'male')

// An error will be reported here because NAME has been defined and JS can be changed at any time

define('NAME', 'error');

3. Array

Sort by:

You can use shuffle(). In JS, we usually use Math.random to set the subscript of the array within a certain range; if you use numbers to sort, the decimal point will be ignored, so if you want to use it accurately Sort numbers and turn numbers into strings. For example, 1.2 should be written as '1.2'.

代码如下	复制代码
echo 'im sofish,' . PHP_EOL; echo "25 years old, n"; echo 'male';

Can use string as key:

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$arr = array('name' => 'sofish', 'age' => '25', 'gender' => 'male');

Automatically increase index value: The following two data are the same:

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$arr = array('1' => ; 'sofish', '25', 'male') $arr = array('1' => 'sofish', '2' => '25', '3' => 'male')

4. Hyphen Use . in PHP and + in JS. 5. Line break When using "n" within double quotes, 'n' is not converted to a newline character. If you are used to using single quotes, you can use PHP_EOL:

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echo 'im sofish,' . PHP_EOL; echo "25 years old, n"; echo 'male';

// Imagine the following paragraph, the most popular answer on stackoverflow
// Personally, I don’t like mixing two types of quotation marks. It doesn’t look good, but it’s not necessarily bad. lol?!
echo 'im sofish' . "n" . '25 ...' In JS, writing n inside quotation marks is feasible.

6. if statement
In PHP, the other branch uses elseif and in JS, there is a space difference.

UPDATE: 2012.02.29 5:28 pm: Andor: "In fact, it is possible to use elseif and else if on the other branch of the if branch."

7. Function
In PHP, you cannot use functions like (function(){})() to directly run an anonymous function, but you can create a function with default parameters, such as:

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代码如下	复制代码
function fn($name, $greet = 'good moring '){ echo $greet . $name; };

function fn($name, $greet = 'good morning '){

echo $greet . $name;

};

代码如下	复制代码
fn('sofish', 'good morning ');

// When no value is passed, the default value is displayed, the result is >> 'good morning sofish'

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$a = 'hello'; $b = function(){ echo $a . ' sofish.'; }; $b();

//Replace the default value when passing in a value, the result is >> 'good afternoon sofish'

fn('sofish', 'good afternoon '); scope, I still prefer closures in JS. In PHP, let's take a look at the following code:

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$a = 'hello';

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$a = 'hello'; $b = function(){ global $a; echo $a . ' sofish.'; }; $b();

$b = function(){

echo $a . ' sofish.';

};

$b();

Our expected result is, ‘hello sofish.’. However, there are 2 $b in me, and the results often surprise us. In PHP, variables cannot be used within custom functions, nor can externally defined variables (WTF) be used inside functions unless the global keyword is used. The above function can be used if modified as follows:

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$a = 'hello';

$b = function(){

global $a;

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var cursorPos = (function(){ // render ... return [posX, posY]; })();

echo $a . ' sofish.'; }; $b();

We usually say that global variables should be used with caution. It’s even more needed here. 8. list() function A very interesting function that can assign values to a set of variables using values in an array. This is how we usually use an array in JS: // Return an array, then use `[]` subscript to call

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var cursorPos = (function(){ // render ... Return [posX, posY]; })();

In PHP, you can use list() to assign values to a set of variables based on the contents of the array, so that we can use variables to access the values we want to use instead of using subscripts:

// Use variables in brackets to access the value returned by the function `cursorPos`
list($posX, $posY) = cursorPos(); In addition, another interesting function worth mentioning isset(), which determines whether a value is NULL. There are also functions such as is_array / is_string, which are not provided in JS. Type judgment is considered a high-level content in JS. Only programmers who are familiar with it and have accumulated experience know how to do it reasonably.