PHP array learning sorting full contact page 1/2_PHP tutorial-PHP Tutorial-php.cn

PHP array learning sorting full contact page 1/2_PHP tutorial

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Release： 2016-07-21 15:44:55

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array_values($arr) array
Returns all elements of the array

Copy code The code is as follows:

 
$arr = array("a", "b", "c"); 
$arr = array_flip($arr); //Reverse the subscript and value of the array. Now $arr = array(0 , 1, 2); 
$arr = array_values($arr); //Return all elements in array $arr
print_r($arr); //Result: array(0, 1, 2); 
?> 

array_walk($arr, $func, [$data]) bool
Use user-defined function to traverse all elements and return true/false
Note: This function only processes the first dimension of the array
$func is a function name
By default, the value of the first $arr of the two parameters will be passed in, and the subscript of the second $arr. Pass one-to-one

Copy code The code is as follows:

$arr = array('a ', 'b', 'c'); 
array_walk($arr, 'test'); //The second parameter test here is the function name
function test(&$val, $key) // The first parameter here is added with a reference, then modifying $val is equivalent to modifying the element in $arr 
{ 
$val = 'x_' . $val; //Add a prefix to it here 
} 
print_r($arr); //Output result array('x_a', 'x_b', 'x_c'); 
//If $arr is changed here, $arr = array('a', ' b', 'c', array(1, 2, 3)); The printed result will be array('x_a', 'x_b', 'x_c', 'x_Array'); 
?> 

Now pass in the third parameter $data. If there is a third parameter passed in, then the third parameter will be passed to the third parameter in the function defined by the second parameter

Copy code The code is as follows:

 
array_walk($arr, 'test', 'x_'); 
function test(&$val, $key, $prefix) 
{ 
$val = $prefix . $val; //In fact, the $prefix here is the x_ above 
} 
print_r( $arr); //The output result is the same as above array('x_a', 'x_b', 'x_c'); 
?> 

arsort($arr) bool
Arrange the array $arr in reverse order and retain the relationship between subscripts and values. If the sorting is successful, return true, otherwise return false
This function only processes the first dimension of the array

Copy code The code is as follows:

 
$arr = array('a' => 'a', 'b' => ' b', 'c' => 'c'); 
arsort($arr); 
print_r($arr); //Print results: array('c' => 'c', ' b' => 'b', 'a' => 'a'); If there are numbers, the numbers will be in front of the characters 
?> 

asort($arr) bool
Arrange the array $arr in positive order, that is, arrange it like a-z, and the return value is the same as above
This function also retains the relationship between subscripts and values

Copy code The code is as follows:

 
$arr = array('a' => 'a', 'b' => 'b', ' c' => 'c'); 
asort($arr); 
print_r($arr); //The result has not changed, it is the original array
$arr = array('c' = > 'c', 'b' => 'b', 'a' => 'a'); 
asort($arr); 
print_r($arr); //Result: array ('a' => 'a', 'b' => 'b', 'c' => 'c'); 
?> 

compact($ varname, ...., $varname) array
accepts n $varnames and uses $varname as a subscript. The value of $varname is used as a value to create an array. $varname can be explained unclearly for array
. See example

Copy code The code is as follows:

 
$a = "Variable a"; 
$ b = "Variable b"; 
$arr = compact('a', 'b'); // Here a and b are passed in as the variable names defined above 
print_r($arr); //Print the result is array('a' => 'Variable a', 'b' => 'Variable b'); 
//You can also pass the variable name as an array 
$vars = array('a ', 'b'); 
$arr = compact($vars); 
print_r($arr); //The result is the same as above. In fact, this function does the opposite operation of extract
?> 

extract($arr, $type, $prefix) int
Use the subscript of the array $arr as the variable name, and the value as the variable value
$arr target array
$type This is what I have encountered What method should be used when encountering the same subscript? The value is a constant defined by PHP
EXTR_OVERWRITE. If they are the same, then the previous variable will be overwritten. The default is this
EXTR_SKIP. If they are the same, the previous variable will not be overwritten
EXTR_PREFIX_SAME If they are the same, then use the third parameter $prefix to add to the variable name
EXTR_PREFIX_ALL Add $prefix to all variable names as a prefix
Note that the parameter $ needs to be passed in only when $type is EXTR_PREFIX_SAME or EXTR_PREFIX_ALL prefix, otherwise it will be useless to pass it. . .
Example

Copy code The code is as follows:

 
$arr = array('a ' => 'Variable a', 'b' => 'Variable b'); 
extract($arr, EXTR_OVERWRITE); //If there are the same, overwrite 
echo $a; //Output The result will be 'Variable a' 
echo $b; //Result: 'Variable b' 
$arr = array('a' => 'Variable a', 'b' => 'Variable b ', 'a' => 'The second variable a'); //There are two elements here with subscripts a 
extract($arr); 
echo $a; //The output result is : 'Second variable a' has obviously overwritten 'variable a' because the default second parameter is EXTR_OVERWRITE 
?> 

count($arr) int
Count the number of elements in the array

Copy code The code is as follows:

 
$arr = array('a', 'b'); 
echo count($arr); //Obviously the result is 2 
?> 

current($arr) mixed
Returns the element pointed to by the current pointer in the array. This function alias pos

Copy code The code is as follows:

 
< ;?php 
$arr = array('a', 'b', 'c'); 
echo current($arr); //The result is 'a' 
echo next($arr) ; //The pointer moves to the next point, so now the pointer points to b. The output result is of course 'b' 
echo current($arr); //The result is b again because the current pointer is at b
echo end($arr) //The pointer moves to the end of the array and the result is returned, so the result is c 
echo prev($arr); //The pointer moves up one, the result is b 
echo key($arr : 🎜>?> 

 

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