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[Introduction] 1. Custom functions Custom functions are functions defined by ourselves. The format of custom functions in PHP is as follows: function funname(arg1, arg2, arg3 ){ TODOreturn values;}
# custom function is the function of our own definition. The custom function format in PHP is as follows:
# Function funname (ARG1, arg2, arg3...){
//TODO
return values;
}
Output result:
Here is another function with variable parameters
"; // 2*1*2 = 4
echo fun($p, 3)."
"; // 2*3*2 = 12
echo fun($p, 3, 3)."
"; // 2*3*3 = 18
?>
Let’s take a look at custom function reference passing
"; // 2*1*2 = 4
echo fun($p, 3)."
"; // 2*3*2 = 12
echo fun($p, 3, 3)."
"; // 2*3*3 = 18
*/
function fun(&$n){
$n=$n*$n;
}
$p=2;
fun($p);
echo $p;
?>
1. Basic writing format of array
Simple form: array(value 1, value 2, value 3, .......)
array("aa", 12, true, 2.2, "test", 50); //Get data through array subscript
Full form: array(key 1=>value 1 , key 2=>value 2, ...)
array("title"=>"aa", "age"=>20); //Only by key name Obtain data
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';
1. Modify
$arr=array(11, 22, 33, 44);
$arr[0]=55; //The array becomes $arr=array(55, 22, 33, 44);
2. Delete
$arr =array(11, 22, 33, 44);
unset($arr[0]); //The array becomes $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. Traversal
$arr=array('a'=>11, 'b'=>22, 'c'=>33, 'd'=>44);
foreach($arr as $value){ //No key name
echo $value."
";
}
foreach ($arr as $id=>$value){ //Output key and value
echo $id..$value."
";
}
$arr=array(array("1","11","111"), array("2","22","222"));
echo $arr[1 ][2];
（1）array_change_key_case(array, case)
array: required, array.
case: Optional, CASE_LOWER (default value, lowercase letters return the keys of the array), CASE_UPPER (uppercase letters return the keys of the array)
Function: Convert all KEYs of the array to Uppercase or lowercase.
"Cat","b"=>"Dog","c"=>"Horse");
print_r(array_change_key_case($a,CASE_UPPER));
?>
结果：Array ( [A] => Cat [B] => Dog [C] => Horse )
"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));
?>
结果： 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 ) )
| Function | describe | 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 blocks. | 4 |
| array_combine() | Create a new array by merging two arrays. | 5 |
| array_count_values() | Used to count the number of occurrences of all values in the array. | 4 |
| array_diff() | Return 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 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 and calculate the difference set of the array. | 5 |
| array_fill() | Fill the array with the given values. | 4 |
| array_filter() | Use the callback function to filter the elements in the array. | 4 |
| array_flip() | Exchange keys and values in the array. | 4 |
| array_intersect() | Calculate the intersection of arrays. | 4 |
| array_intersect_assoc() | Compare the key name and key value, and return the intersection array of the two arrays. | 4 |
| array_intersect_key() | Use key name comparison to calculate the intersection of arrays. | 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 key names to calculate the intersection of arrays. | 5 |
| array_key_exists() | Check whether the given key name or index exists in the array. | 4 |
| array_keys() | Return all key names in the array. | 4 |
| array_map() | Apply the callback function to the cells of the given array. | 4 |
| array_merge() | Combine 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() | Pall 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 the 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. | 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() | Delete the first element in the array and return the value of the deleted element. | 4 |
| array_slice() | Retrieve a 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 the array. | 4 |
| array_udiff() | Use callback function to compare data to calculate the difference of arrays. | 5 |
| array_udiff_assoc() | With index check, calculate the difference set of the array, 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() | With index check, calculate the intersection of arrays, and use callback function to compare data and index. | 5 |
| array_unique() | Delete duplicate values in the array. | 4 |
| array_unshift() | Insert one or more elements at the beginning of the array. | 4 |
| array_values() | Return all values in the array. | 4 |
| array_walk() | Apply the user function to each member of the array. | 3 |
| array_walk_recursive() | Apply the user function recursively to each member of the 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() | Return 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() | Check 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() | Sort the array using the "natural sorting" algorithm. | 4 |
| next() | Move the internal pointer in the array forward one bit. | 3 |
| pos() | 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 |
| sizeof() | An alias for count(). | 3 |
| sort() | Sort the array. | 3 |
| uasort() | Use a user-defined comparison function to sort the values in the array and maintain index association. | 3 |
| uksort() | Use user-defined comparison function to sort the key names in the array. | 3 |
| usort() | Use user-defined comparison function to sort the values in the array. | 3 |
1. Custom function
Custom functions are functions we define ourselves. The format of custom functions in PHP is as follows:
function funname(arg1, arg2, arg3...){
//TODO
return values;
}
Output result:
Here is another function with variable parameters
"; // 2*1*2 = 4 echo fun($p, 3)."
"; // 2*3*2 = 12 echo fun($p, 3, 3)."
"; // 2*3*3 = 18 ?>
Let’s take a look at custom function reference passing
"; // 2*1*2 = 4 echo fun($p, 3)."
"; // 2*3*2 = 12 echo fun($p, 3, 3)."
"; // 2*3*3 = 18 */ function fun(&$n){ $n=$n*$n; } $p=2; fun($p); echo $p; ?>
2. Array definition and assignment
1. Basic writing format of array
Simple form: array(value 1, value 2, value 3, .......)
array("aa", 12, true, 2.2, "test", 50); //Get data through array subscript
Full form: array(key 1=>value 1, key 2=>value 2, ...)
array("title"=>"aa", "age"=>20); //Data can only be obtained through key names
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 operations
1. Modification
$arr=array(11, 22, 33, 44);
$arr[0]=55; //The array becomes $arr=array(55, 22, 33, 44);
2. Delete
$arr=array(11, 22, 33, 44);
unset($arr[0]); //The array becomes $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. Traversal
$arr=array('a'=>11, 'b'=>22, 'c'=>33, 'd'=>44);
foreach($arr as $value){ //No key name
echo $value."
";}
foreach($arr as $id=>$value){ //Output key and value
echo $id..$value."
";}
4. Two-dimensional array
$arr=array(array("1","11","111"), array("2","22","222"));
echo $arr[1][2];
5. Array function
（1）array_change_key_case(array, case)
array: required, array.
case: optional, CASE_LOWER (default value, lowercase letters return the key of the array), CASE_UPPER (uppercase letters return the key of the array)
Function: Convert all KEYs in the array to uppercase or lowercase.
"Cat","b"=>"Dog","c"=>"Horse"); print_r(array_change_key_case($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.
"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)); ?> 结果：
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 using them, the list is as follows (php represents the first version)
Function describe 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 blocks. 4 array_combine() Create a new array by merging two arrays. 5 array_count_values() Used to count the number of occurrences of all values in the array. 4 array_diff() Return 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 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 and calculate the difference set of the array. 5 array_fill() Fill the array with the given values. 4 array_filter() Use the callback function to filter the elements in the array. 4 array_flip() Exchange keys and values in the array. 4 array_intersect() Calculate the intersection of arrays. 4 array_intersect_assoc() Compare the key name and key value, and return the intersection array of the two arrays. 4 array_intersect_key() Use key name comparison to calculate the intersection of arrays. 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 key names to calculate the intersection of arrays. 5 array_key_exists() Check whether the given key name or index exists in the array. 4 array_keys() Return all key names in the array. 4 array_map() Apply the callback function to the cells of the given array. 4 array_merge() Combine 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() Pall 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 the 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. 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() Delete the first element in the array and return the value of the deleted element. 4 array_slice() Retrieve a 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 the array. 4 array_udiff() Use callback function to compare data to calculate the difference of arrays. 5 array_udiff_assoc() With index check, calculate the difference set of the array, 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() With index check, calculate the intersection of arrays, and use callback function to compare data and index. 5 array_unique() Delete duplicate values in the array. 4 array_unshift() Insert one or more elements at the beginning of the array. 4 array_values() Return all values in the array. 4 array_walk() Apply the user function to each member of the array. 3 array_walk_recursive() Apply the user function recursively to each member of the 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() Return 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() Check 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() Sort the array using the "natural sorting" algorithm. 4 next() Move the internal pointer in the array forward one bit. 3 pos() 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 sizeof() An alias for count(). 3 sort() Sort the array. 3 uasort() Use a user-defined comparison function to sort the values in the array and maintain index association. 3 uksort() Use user-defined comparison function to sort the key names in the array. 3 usort() Use user-defined comparison function to sort the values in the array. 3
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