1. Custom functions
Custom functions are functions defined by ourselves, customized in PHP The function format is as follows:
function funname(arg1, arg2, arg3......){ //TODO return values; }
<?php function fun($m, $n){ if($m==0 || $n==0){ return 0; }else{ $a=$m*$n; return $a; } } $p=2; $h=3; echo $p."*".$h."=".fun($p,$h); ?>
Output result:
Let’s take another function with variable parameters
<?php /* function fun($m, $n){ if($m==0 || $n==0){ return 0; }else{ $a=$m*$n; return $a; } } $p=2; $h=3; echo $p."*".$h."=".fun($p,$h); */ function fun($m, $n=1, $x=2){ $a=$m*$n*$x; return $a; } $p=2; echo fun($p)."<br>"; // 2*1*2 = 4 echo fun($p, 3)."<br>"; // 2*3*2 = 12 echo fun($p, 3, 3)."<br>"; // 2*3*3 = 18 ?>
<?php /* function fun($m, $n){ if($m==0 || $n==0){ return 0; }else{ $a=$m*$n; return $a; } } $p=2; $h=3; echo $p."*".$h."=".fun($p,$h); */ /* function fun($m, $n=1, $x=2){ $a=$m*$n*$x; return $a; } $p=2; echo fun($p)."<br>"; // 2*1*2 = 4 echo fun($p, 3)."<br>"; // 2*3*2 = 12 echo fun($p, 3, 3)."<br>"; // 2*3*3 = 18 */ function fun(&$n){ $n=$n*$n; } $p=2; fun($p); echo $p; ?>
##2. Array definition assignment
Simple form: array(value 1, Value 2, value 3, …….)
array(“aa”, 12, true, 2.2, “test”, 50); //Get data through array subscript
Complete Format: array(key 1=>value 1, key 2=>value 2, …)
array(“title”=>”aa”, “age”=>20); //The data can only be obtained through the key name
2. How to create an array
//第一种 $arr1=array(11, 22, 33, "44"); //第二种 $arr2=array('a'=>'11', 'b'=>'22'); //第三种 $arr3[0]='20'; $arr3[1]='30';
3. Array operation
$arr=array(11, 22, 33, 44); $arr[0]=55; //数组变为$arr=array(55, 22, 33, 44);
2. Delete
$arr=array(11, 22, 33, 44); unset($arr[0]); //数组变为$arr=array(22, 33, 44);
3. Use
$arr=array(11, 22, 33, 44); echo $arr[0]; $arr=array('a'=>11, 'b'=>22, 'c'=>33, 'd'=>44); echo $arr['b']];
4. Traverse
$arr=array('a'=>11, 'b'=>22, 'c'=>33, 'd'=>44); foreach($arr as $value){ //无键名 echo $value."<br>"; } foreach($arr as $id=>$value){ //输出键和值 echo $id..$value."<br>"; }
4. Two-dimensional array
$arr=array(array("1","11","111"), array("2","22","222")); echo $arr[1][2];
5. Array function
(1)
array_change_key_case(array, case)array: required, array.
case: Optional, CASE_LOWER (default value, lowercase letters return the keys of the array), CASE_UPPER (uppercase letters return the keys of the array)
Function: Convert all KEYs of the array to Uppercase or lowercase.
<?php $a=array("a"=>"Cat","b"=>"Dog","c"=>"Horse"); print_r(array_change_key_case($a,CASE_UPPER)); ?> 结果:Array ( [A] => Cat [B] => Dog [C] => Horse )
(2)array_chunk(array,size,preserve_key)
array: required.
size: Required, specifies how many elements each new array contains.
preserve_key: optional, true (preserve key name), false (new index)
Function: Divide an array into new array blocks.
<?php //array_chunk(array,size,preserve_key) $a1=array("a"=>"Cat","b"=>"Dog","c"=>"Horse","d"=>"Cow"); print_r(array_chunk($a1,2)); $a2=array("a"=>"Cat","b"=>"Dog","c"=>"Horse","d"=>"Cow"); print_r(array_chunk($a2,2,true)); ?>
Array ( [0] => Array ( [0] => Cat [1] => Dog ) [1] => Array ( [0] => Horse [1] => Cow ) )
Array ( [0] => Array ( [a] => Cat [b] => Dog ) [1] => Array ( [c] => Horse [ d] => Cow ) )
…….
There are many functions like this, you can check them when you use them, the list is as follows (php represents the first version)
Function | Description | PHP |
---|---|---|
array() | Create an array . | 3 |
array_change_key_case() | Returns an array whose keys are all uppercase or lowercase. | 4 |
array_chunk() | Split an array into new array chunks. | 4 |
array_combine() | Creates a new array by merging two arrays. | 5 |
array_count_values() | is used to count the number of occurrences of all values in the array. | 4 |
array_diff() | Returns the difference array of two arrays. | 4 |
array_diff_assoc() | Compare the key name and key value, and return the difference array of the two arrays. | 4 |
array_diff_key() | Compare the key names and return the difference array of the two arrays. | 5 |
array_diff_uassoc() | Calculate the difference set of the array by doing index checking through the callback function provided by the user. | 5 |
array_diff_ukey() | Use the callback function to compare the key names to calculate the difference set of the array. | 5 |
array_fill() | Fills the array with the given value. | 4 |
array_filter() | Use the callback function to filter the elements in the array. | 4 |
array_flip() | Exchange the keys and values in the array. | 4 |
array_intersect() | Calculate the intersection of arrays. | 4 |
array_intersect_assoc() | Compares the key name and key value, and returns the intersection array of the two arrays. | 4 |
array_intersect_key() | Calculate the intersection of arrays using key name comparison. | 5 |
array_intersect_uassoc() | Calculate the intersection of arrays with index checking, and use the callback function to compare the indexes. | 5 |
array_intersect_ukey() | Use the callback function to compare the key names to calculate the intersection of the arrays. | 5 |
array_key_exists() | Checks whether the given key name or index exists in the array. | 4 |
array_keys() | Returns all key names in the array. | 4 |
array_map() | Apply the callback function to the cells of the given array. | 4 |
array_merge() | Merge one or more arrays into one array. | 4 |
array_merge_recursive() | Recursively merge one or more arrays. | 4 |
array_multisort() | Sort multiple arrays or multidimensional arrays. | 4 |
array_pad() | Pads the array to the specified length with values. | 4 |
array_pop() | Pop the last unit of the array (pop off the stack). | 4 |
array_product() | Calculate the product of all values in an array. | 5 |
array_push() | Push one or more units (elements) to the end of the array (push). | 4 |
array_rand() | Randomly select one or more elements from the array and return it. | 4 |
array_reduce() | Use the callback function to iteratively reduce the array to a single value. | 4 |
array_reverse() | Reverse the order of elements in the original array, create a new array and return it. | 4 |
array_search() | Search for the given value in the array and return the corresponding key name if successful. | 4 |
array_shift() | Deletes the first element in the array and returns the value of the deleted element. | 4 |
array_slice() | Remove a segment of value from the array based on conditions and return it. | 4 |
array_splice() | Remove part of the array and replace it with other values. | 4 |
array_sum() | Calculate the sum of all values in an array. | 4 |
array_udiff() | Use the callback function to compare data to calculate the difference of the array. | 5 |
array_udiff_assoc() | Calculate the difference set of the array with index check, and use the callback function to compare the data. | 5 |
array_udiff_uassoc() | With index check, calculate the difference set of the array, and use the callback function to compare the data and index. | 5 |
array_uintersect() | Calculate the intersection of arrays and use callback functions to compare data. | 5 |
array_uintersect_assoc() | Calculate the intersection of arrays with index checking, and use callback functions to compare data. | 5 |
array_uintersect_uassoc() | Calculate the intersection of arrays with index checking, and use the callback function to compare the data and index. | 5 |
array_unique() | Remove duplicate values from the array. | 4 |
array_unshift() | Insert one or more elements at the beginning of the array. | 4 |
array_values() | Returns all the values in the array. | 4 |
array_walk() | Apply a user function to each member of the array. | 3 |
array_walk_recursive() | Applies a user function recursively to each member of an array. | 5 |
arsort() | Reverse sort the array and maintain the index relationship. | 3 |
asort() | Sort the array and maintain the index relationship. | 3 |
compact() | Create an array, including variable names and their values. | 4 |
count() | Calculate the number of elements in the array or the number of attributes in the object. | 3 |
current() | Returns the current element in the array. | 3 |
each() | Returns the current key/value pair in the array and moves the array pointer forward one step. | 3 |
end() | Point the internal pointer of the array to the last element. | 3 |
extract() | Import variables from the array into the current symbol table. | 3 |
in_array() | Checks whether the specified value exists in the array. | 4 |
key() | Get the key name from the associative array. | 3 |
krsort() | Sort the array in reverse order by key name. | 3 |
ksort() | Sort the array by key name. | 3 |
list() | Assign the values in the array to some variables. | 3 |
natcasesort() | Use the "natural sorting" algorithm to sort the array in a case-insensitive manner. | 4 |
natsort() | Sorts the array using the "natural sorting" algorithm. | 4 |
next() | Move the internal pointer in the array forward one position. | 3 |
pos() | An alias for current(). | 3 |
prev() | Rewind the internal pointer of the array by one bit. | 3 |
range() | Create an array containing elements in the specified range. | 3 |
reset() | Point the internal pointer of the array to the first element. | 3 |
rsort() | Sort the array in reverse order. | 3 |
shuffle() | Rearrange the elements in the array in random order. | 3 |
Alias for sizeof() | count(). | 3 |
sort() | Sort the array. | 3 |
uasort() | Use a user-defined comparison function to sort the values in an array and maintain index association. | 3 |
uksort() | Use a user-defined comparison function to sort the key names in the array. | 3 |
usort() | Use a user-defined comparison function to sort the values in the array. | 3 |
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