Summary of basic knowledge of PHP arrays_PHP tutorial

/*
#Array None Limit size: $arr[0]=1;$arr[1]=2; $arr=array("0","1");$list($num1,$num2)=$arr;
array range(int low,int high[,int step])
low minimum number, high maximum number, step step size
int array_unshift(array array, mixed vari) Insert in front of array
array_push Add to end of array
array_shift Array head deletion
array_pop Array tail deletion
#Locate array
boolean in_array(mixed needle,array haystack,[,boolean strict])
boolean array_key_exists(mixed key,array array) Search key keys
array_search() Search associative array values
array_keys() returns an array containing all the keys searched
array_values() returns all values ​​of the array.
#Traverse the array
mixed key(array array)
current(array array) Get the current array value
array each(array array) Return the current key, value pair
next(array array) Point to the next
prev(array array) Move to the previous
reset(array array) Move to the first
end(array array) Move to the last
# Pass the array value to the function
boolean array_walk(array &array,callback function,[,mixed userdata])
#Determine the size and uniqueness of the array
integer count(array array[,int mode]) similar to sizeof()
array array_count_values(array array) Group and count the number of occurrences of each value
array_unique() Delete duplicate values ​​and maintain uniqueness
#Sort
array_reverse() Reverse the order
array_flip() Swap keys with Value
void sort(array array[,int sort_flags])
sort_flgs{[SORT_NUMBERIC numerical sort],[SORT_REGULAR sort by ASCII],[SORT_STRING]}
asort() ascending order
rsort() Reverse order
arsort() Reverse order
natsort() Natural sort
natcasesort() Case-insensitive natural sort
ksort() Key-value sort
krsort() Reverse key-value sort
void usort(array array, callback function name) User-defined sorting
#Merge, split, combine, decompose arrays
array_merge_recursive() merge
array_merge_combine() append
array_merge() connect to new Array
array_slice(array array,int offset[,int length]) split
array_intersect(), array_intersect_assoc() array intersection
array_diff(), array_diff_assoc() difference
array_rand(), shuffle()random array
array_sum()summation
array_chunk is divided into multi-dimensional arrays
*/
//Create an even array of 0-20, 2 is the step size
$even=range( 0,20,2);
//Print array
print_r($even);
//Judge whether it is an array
printf("this number is an array:%s
echo "
";
//Add sub-items to the head of the array and print
array_unshift( $even,522,54);
print_r($even);
//Define a variable and then search in the array. If the variable exists, it will be displayed.
$sa=522;
if(in_array($sa,$even)){
echo "find it $sa";
};
echo "
";
//Search array key
if(array_key_exists(4,$even)){
echo $even[4]." exists.";
}
echo "< ;br/>";
print_r(array_values($even));
//Traverse the print array
while($key=key($even)){
echo "
".$key;
next($even);
}
//Statistical array size
echo "
";
echo count($even );
//Sort
echo "
";
sort($even);
print_r($even);
?>