PHP commonly used functions - array PHP commonly used string functions PHP commonly used class libraries PHP commonly used English singles

In the process of learning PHP, I compiled some commonly used functions. These are array functions.

//array(): Generate an array
$a = array("dog","cat","horse");
print_r($a); //Array ( [0] = > dog [1] => cat [2] => horse )
//array_combine(): Generate an array, using the value of one array as the key name and the value of the other array as the value
$a1 = array ("a","b","c","d");
$a2 = array("Cat","Dog","Horse","Cow");
print_r(array_combine($a1,$ a2)); //Array ( [a] => Cat [b] => Dog [c] => Horse [d] => Cow )
//range(): Create and return an array containing elements in the specified range.
$number = range(0,50,10); //(0: the first value of the sequence; 50: the end value of the sequence; 10: the step size each time)
print_r ($number); //Array ( [0] => 0 [1] => 10 [2] => 20 [3] => 30 [4] => 40 [5] => 50 )
//compact(): Create an array composed of variables carried by parameters
$firstname = "Peter";
$lastname = "Griffin";
$age = "38";
$result = compact("firstname" , "lastname", "age");
print_r($result); //Array ( [firstname] => Peter [lastname] => Griffin [age] => 38 )
//array_fill(): Generate an array with the given value
$a = array_fill(2,3,"Dog"); //(2: The first key value to be filled; 3: The value to be filled; dog: fill in the content)
print_r($a); //Array ( [2] => Dog [3] => Dog [4] => Dog )
//array_chunk(): put an array Split into new array blocks
$a = array("a"=>"cat","b"=>"dog","c"=>"horse","d"=>"Cow ");
print_r(array_chunk($a,2)); //Array([0] => Array([a]=>cat [b]=>dog) [1] => Array( [c]=>horse [d]=>cow))
//array_merge(): Merge two arrays into one array
/***********************Differences between array_combine******************************
array_merge( ): Merge arrays directly; array_combine(): According to the order of parameters, the first group is the key and the second group is the value;*/
echo "

---

" ;
$a1 = array("a"=>"Horse","b"=>"Dog");
$a2 = array("c"=>"Cow","b"=> "cat");
print_r(array_merge($a1,$a2)); //Array ( [a] => Horse [b] => Dog [c] => Cow [d] => cat )
//array_diff(): Returns the difference between the two arrays (the key names remain unchanged)
$a1 = array(8=>"Cat",1=>"Dog",2=>"Horse" ,3=>"lion");
$a2 = array(4=>"Horse",5=>"Dog",6=>"bird",7=>"pig");
print_r(array_diff($a1,$a2)); //Array ( [8] => Cat [3] => lion )
print_r(array_diff($a2,$a1)); //Array ( [6 ] => bird [7] => pig )
//array_intersect(): Returns the intersection array of two or more arrays
$a1 = array(0=>"Cat",1=>"Dog ",2=>"Horse");
$a2 = array(3=>"Horse",4=>"Dog",5=>"Fish");
print_r(array_intersect($a1, $a2)); // Array ( [1] => Dog [2] => Horse )
print_r(array_intersect($a2,$a1)); // Array ( [3] => Horse [4 ] => Dog )
//array_serach searches for the given value in the array, and returns the corresponding key name if successful (returns false on failure)
$a = array("a"=>"Dog","b "=>"Cat","c"=>"Horse");
echo array_search("Dog",$a); //a
//array_slice(): Remove a value from the array based on conditions, And return (the key name remains unchanged)
echo "
";
$a = array("a"=>"Dog","b"=>"Cat","c"= >"Horse","d"=>"Bird");
print_r(array_slice($a,1,2)); //1: Start from the key value (equivalent to the position where the index key is 1) ;2. Take two
//Array ( [b] => Cat [c] => Horse )
//array_splice(): Remove part of the array and replace it with other values ​​
$a1 = array (4=>"Dog",'b'=>"Cat",'c'=>"Horse",6=>"Bird");
$a2 = array(3=>"Tiger ",5=>"Lion");
array_splice($a1,1,2,$a2);
/* $a1: The replaced array (the last array output); 1: 1 according to the index key Start replacing at the position; 2: Replace two; $a2: Replace the array and add it to $a1*/
print_r($a1); //Array ( [0] => Dog [1] => Tiger [ 2] => Lion [3] => Bird )
//array_splice($a1,0,2,$a2);
//print_r($a1); // Array ( [0] => Tiger [1] => Lion [2] => Horse [3] => Bird )
//array_sum(): Calculate the sum of all values ​​in the array
$a = array(0=>"5", 1=>"15",2=>"25");
echo array_sum($a); //45
//in_array(): Check whether a certain value exists in the array
$animals = array(" dog", "cat", "cow", "horse");
if (in_array("cow",$animals)){
echo "Match found";
}else{
echo "Match not found";
}
//array_key_exists(): Check whether the given key name exists in the array (parameter 1: key name parameter 2: array): return bool value
$animals = array("a"=>"dog", " b"=>"cat", "c"=>"cow", "d"=>"horse","d"=>"lion");
echo array_key_exists("a",$animals ); //1 does not return false value
$search_array = array('first' => 1, 'second' => 4);
if (array_key_exists('first', $search_array)) {
echo " The 'first' element is in the array";
} //The 'first' element is in the array
/* Array pointer operation*/
//key(): Returns the key name of the element currently pointed to by the array's internal pointer
//current(): Returns the current element of the array
//next(): Moves the pointer pointing to the current element to the position of the next element, and returns the value of the current element
//prev(): Moves the pointer pointing to the current element The pointer moves to the position of the previous element and returns the value of the current element
//end(): Points the current internal pointer to the last element and returns the value of the element
//reset(): Points the array element pointer to the A value and returns the value of this element
$array = array(
'fruit1' => 'apple',
'fruit2' => 'orange',
'fruit3' => 'grape',
'fruit4' => 'apple',
'fruit5' => 'apple');
while ($fruit_name = current($array)) {
if ($fruit_name == 'apple') {
echo key ($array).'
';
}
next($array);
} //fruit1 fruit4 fruit5
/* Traverse the array*/
/*Traverse in the forward direction*/
$a = array (10,20,30);
reset($a);
do{
echo key($a)."==>".current($a)."
";
} while(next($a)); // 0==>10 1==>20 2==>30
/*Backward traversal*/
end($a);
do{
echo key ($a)."===>".current($a)."
";
}while(prev($a)); //2===>30 1===>20 0===>10
/* pointer*/
$transport = array('foot', 'bike ', 'car', 'plane');
/*The first one is the current element by default*/
$mode = current($transport); // $mode = 'foot';
$mode = next($transport ); // $mode = 'bike';
/*The current element is 'bike'*/
$mode = current($transport); // $mode = 'bike';
$mode = prev($transport) ; // $mode = 'foot';
$mode = end($transport); // $mode = 'plane';
$mode = current($transport); // $mode = 'plane';
/ /list(): Assign the values ​​in the array to some variables---------list is not a function
$arr = array("Cat","Dog","Horse","Cow");
list($a,$b,$c,$d) = $arr;
echo $a; //Cat
echo $b; //Dog
echo $c; //Horse
echo $d; //Cow
//array_shift(): Delete the first element in the array and return the value of the deleted element
$a = array("1"=>"Dog","2"=>"Cat"," 3"=>"Horse");
echo array_shift($a); //Dog
print_r ($a); //Array ( [b] => Cat [c] => Horse )
// array_unshift(): Insert one or more elements into the array switch (if the current array is an index array, it starts from 0, and so on; the associative array key name remains unchanged)
$a = array("10"=>" Cat","b"=>"Dog",3=>"horse",5=>"lion");
array_unshift($a,"Horse");
print_r($a); // Array ( [0] => Horse [1] => Cat [b] => Dog [2] => horse [3] => lion )
//array_push(): Push one or more elements into the array at the end
$a=array("a"=>"Dog","3"=>"Cat");
array_push($a, "Horse","Bird");
print_r($a); //Array ( [a] => Dog [3] => Cat [4] => Horse [5] => Bird )
//array_pop(): Delete the last element in the array
$a=array("Dog","Cat","Horse");
array_pop($a);
print_r($a); //Array ( [0] => Dog [1] => Cat )
/* Array key value operation */
//shuffle(): shuffle the array, the key name index array starts from 0 (shuffle cannot be printed directly, Write separately)
$animals = array("a"=>"dog", "b"=>"cat", "c"=>"cow", "d"=>"horse"," d"=>"lion");
shuffle($animals);
print_r($animals); //Array ( [0] => dog [1] => cow [2] => cat [ 3] => lion ) will change randomly every time it is refreshed
//count(): Calculate the number of units in the array and the number of attributes in the object
$people = array("Peter", "Joe", "Glenn" , "Cleveland");
echo count($people); //4
//array_flip(): Returns an array with the key values ​​reversed
$a = array(0=>"Dog",1=> ;"Cat",2=>"Horse");
print_r(array_flip($a)); //Array ( [Dog] => 0 [Cat] => 1 [Horse] => 2 )
//array_keys(): Returns all the keys of the array to form an array
$a = array("a"=>"Horse","b"=>"Cat","c"=>"Dog ");
print_r(array_keys($a)); //Array ( [0] => a [1] => b [2] => c )
//array_values(): Returns all items in the array values, forming an array
$a = array("a"=>"Horse","b"=>"Cat","c"=>"Dog");
print_r(array_values($a )); //Array ( [0] => Horse [1] => Cat [2] => Dog )
//array_reverse(): Returns an array with the elements in the reverse order
$a = array(" a"=>"Horse","b"=>"Cat","c"=>"Dog");
print_r(array_reverse($a)); //Array ( [c] => Dog [b] => Cat [a] => Horse )
//array_count_values(): Count the number of occurrences of all values ​​in the array
$a = array(1,2,3,4,1,1,3 ,5,3,2,1,3,4);
print_r(array_count_values($a)); //Array ( [1] => 4 [2] => 2 [3] => 4 [ 4] => 2 [5] => 1 )
//array_rand(): Randomly extract one or more elements from the array, note the key name
$a=array("a"=>"Dog ","b"=>"Cat","c"=>"Horse","d"=>"Lion","e"=>"Cow");
print_r(array_rand($a ,3)); //Array ( [0] => b [1] => c [2] => e ) ***Random***
//each(): Returns the current item in the array key/value pairs and move the array pointer one step backward
$foo = array("bob", "fred", "jussi", "jouni", "egon", "marliese");
$bar = each($ foo);
print_r($bar); //Array ( [1] => bob [value] => bob [0] => 0 [key] => 0 )
/* Each time it is traversed, Move the pointer one position backward*/
$bar = each($foo);
print_r($bar); //Array ( [1] => fred [value] => fred [0] => 1 [key] => 1 )
//array_unique():删除重复值，返回剩余数组
$a=array("a"=>"Dog","b"=>"Cat","c"=>"Horse","d"=>"Dog","e"=>"cow","f"=>"Cow");
print_r(array_unique($a)); //Array ( [a] => Dog [b] => Cat [c] => Horse [e] => cow [f] => Cow )
/* 数组排序 */
/**
* The return value is 1 (positive value): indicates exchange order
* The return value is -1 (negative value): indicates no exchange order
**/
/**
* //The original key name is ignored (starting from zero) (string order)
* sort(): Values ​​from small to large
* rsort(): Values ​​from large to small
*
* //Original Key name preservation (string order)
* asort(): sort the values ​​from small to large
* arsort(): sort the values ​​from large to small
**/
$my_array = array("a" => "Dog", "b" => "Cat", "c" => "Horse");
sort($my_array);
print_r($my_array); //Array ( [0] => Cat [1] => Dog [2] => Horse )
$my_array = array("a" => "Dog", "b" => "Cat", "c" => "Horse");
asort($my_array);
print_r($my_array); //Array ( [b] => Cat [a] => Dog [c] => Horse )
/**
* ksort(): Sort the subscripts from small to large
* krsort(): Sort the subscripts from large to small
**/
$my_array = array("h" => "Dog", "s" => "Cat", "a" => "Horse");
ksort($my_array);
print_r($my_array); //Array ( [a] => Horse [h] => Dog [s] => Cat )
$my_array = array("e" => "Dog", "2" => "Cat", "a" => "Horse");//按什么顺序排序
ksort($my_array);
print_r($my_array); //Array ( [a] => Horse [e] => Dog [2] => Cat )
/**
* usort(): Use user-defined callback function to sort the array
* uasort(): Use user-defined callback function to sort the array and maintain index association
* uksort(): Use user-defined callback function to sort the array Array sort sorts array keys
**/
$v = array(1,3,5,2,4);
usort($v,'fun');
function fun($v1,$v2){
return ( $v1 > $v2 ) ? 1 : -1;
}
print_r($v); //Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 )
/* 排序加遍历 */
function cmp($a, $b)
{
if ($a == $b) {
return 0;
}
return ($a < $b) ? -1 : 1;
}
$a = array(3, 2, 5, 6, 1);
usort($a, "cmp");
foreach ($a as $key => $value) {
echo $key."===>".$value." "; //0===>1 1===>2 2===>3 3===>5 4===>6
}
/* 排序遍历结束 */
/**
* sort(): Sort strings from small to large (letters are equal, compare the one digit after unequal)
* natsort(); Natural sort from small to large (letters are equal, compare values)*** Case sensitive
* natcasesort(): Case-insensitive natural sorting
**/
$a = array("a" => "id2", "b" => "id12", "c" => "id22","d" => "ID22");
sort($a); print_r($a); //Array ( [0] => ID22 [1] => id12 [2] => id2 [3] => id22 )
natsort($a); print_r($a); //Array ( [0] => ID22 [2] => id2 [1] => id12 [3] => id22 )
natcasesort($a); print_r($a); //Array ( [2] => id2 [1] => id12 [3] => id22 [0] => ID22 )

以上就介绍了php常用函数-数组，包括了php,常用方面的内容，希望对PHP教程有兴趣的朋友有所帮助。