PHP - API

PHP functions are all capabilities, built more than 1,000 functions, not every function can be used directly by default, some need to install or enable additional "plug-in" expansion.

1, to get the string length

<?php
$str='hello';
echo strlen($str);  //5

2, Chinese character string obtaining length (width characters)

　　strlen can only get the length of Latin

　　php in a set of API to add special characters wide, all of the API are mb_xxxx

echo mb_strlen ( 'Hello');

    　　但是报错：Fatal error: Uncaught Error: Call to undefined function mb_strlen() in              D:\www\site2\02, string.php:7 Stack trace: #0 {main} thrown in D:\www\site2\02, string.php on line 7

　　    This is because it is not built-in set of API 1000+ inside, but in a module (php_mbstring.dll), the module members must use the module again after loading a configuration file

　　 Configuration steps PHP extension

　　1, to create a php.ini in the PHP installation directory (the php.ini-development PHP directory to copy a modified php.ini)

　　2, modify the extension file directory extension_dir 

　　3,; extension = php mbstring.dll, uncomment (some options to modify the file; is the Notes)

　　4, the default Apache is loaded php.ini to C: \ Windows directory to find the

　　5, the load path can modify the default configuration file of Apache by PHPIniDir

 

3, common string API

① string interception

The first parameter: the intercepted string

The second argument: cut out where to begin

The number of characters taken: the third parameter

② string length

③ case conversion

strtolower: uppercase lowercase turn

strtoupper: uppercase lowercase turn

④ remove whitespace characters from beginning to end

⑤ find some of the characters in the string position for the first time

⑥ string replacement

　　Replacing a with b

⑦ Repeat string

The first parameter: repeat string

The second argument: repeated many times

⑧ string split

 

4, array processing

Array type in php: indexed arrays, associative array

php array defined manner: array (), [] (php 5.4+)

① associative array acquires all key / value

　　arrar_keys()   array_values()

<? PHP 
$ ARR = Array (
     ' Hello ' => ' Hello ' ,
     ' Pink ' => ' pink ' ,
     ' Blue ' => ' blue ' , 
); 
var_dump (arrray_key ($ ARR)); // [ 'Hello', 'pink', 'blue']; 
var_dump (array_values ($ ARR)); // [ 'Hello', 'pink', 'blue'];

② determine whether there is a key array

　　array_key_exists()

<?php
$arr=array(
    'hello' => '你好',
    'pink' => '粉色',
    'blue' => '蓝色',
);
var_dump(array_key_exists('hello',$arr));  //bool(true)
var_dump(array_key_exists('world',$arr));  //bool(false)

　　isset may also determine whether a specified key array

<? PHP 
$ ARR = Array (
     ' Hello ' => ' Hello ' ,
     ' Pink ' => ' pink ' ,
     ' Blue ' => ' blue ' , 
); 

IF (isset (ARR $ [ ' Hello ' ] )) { 
    echo $ ARR [ ' Hello ' ]; // hello 
} 
the else { 
    echo ' no ' ; 
}

　　In contrast with isset empty, empty ($ arr [ 'foo']) corresponds! isset ($ arr [ 'foo']) || $ arr [ 'foo'] == false

<? PHP 
$ ARR = Array (
     ' Hello ' => ' Hello ' ,
     ' Pink ' => ' pink ' ,
     ' Blue ' => ' blue ' , 
); 

IF (empty (ARR $ [ ' foo ' ] )) { 
    echo ' no ' ; 
} 
the else { 
    echo $ ARR [ ' foo ' ]; 
}