Summary of examples of using array processing functions in PHP-PHP Tutorial-php.cn

Summary of examples of using array processing functions in PHP

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Release： 2016-07-25 08:43:17

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#Change the case of array keys
$arr1=array("a"=>"Lamp","db"=>"database","LANGUAGE"=> "PHP");
print_r(array_change_key_case($arr1,CASE_UPPER));
echo "
";
print_r(array_change_key_case($arr1,CASE_LOWER));
echo "

";
#Split an array into multiple third parameters to set whether to retain keys
$arr2=array('a','b','c','d','e', 'f','g');
print_r(array_chunk($arr2,2,true));
echo "
";
print_r(array_chunk($arr2,2,false));
echo "

";
#array array_diff_assoc ( array $array1 , array $array2 [, array $ ... ] ) returns an array,
#This array includes all the items in array1 but Values not in any other parameter array
#Different keys count
$arr3=array('a'=>'green','b'=>'brown','c'=>'red' );
$arr4=array('a'=>'green','yellow','red');
print_r(array_diff_assoc($arr3,$arr4));
echo "

";
#array_diff ( array $array1 , array $array2 [, array $ ... ] )
#Returns an array that includes everything in array1 but not in any
#Other parameter arrays Different values and keys are not counted
print_r(array_diff($arr3,$arr4));
echo "

";
#array_fill ( int $start_index , int $num , mixed $value )
#Fill an array with num entries using the value of the value parameter,
#The key name starts with the start_index parameter.
print_r(array_fill(-5,8,"banana"));
echo "

";
#array_flip ( array $trans )
#Return a reversed array , for example, the key name in trans becomes the value,
#And the value in trans becomes the key name.
$arr5=array('a'=>'1',"b"=>"2","c","d","e");
print_r(array_flip($arr5));
echo "

";
#array_map ( callback $callback , array $arr1 [, array $... ] )
#Return an array that contains all cells in arr1 The unit after the callback has been applied to
#. The number of parameters accepted by callback should be consistent with the number of arrays passed to array_map()
#function.
function cube($n){
return $n*$n;
}
$arr6=array(1,2,3,4,5);
print_r(array_map("cube",$arr6));
echo "

";
#array_merge_recursive ( array $array1 [, array $... ] )
#Merge the cells of one or more arrays, and append the values in one array After the previous array
#. Returns the resulting array. If the input arrays have the same string key name,
# then the values will be merged into an array, which will go on recursively, so if a value itself
# is an array, this function will follow the corresponding entry Merge it into another array. However, if
#if the arrays have the same array key name, the latter value will not overwrite the original value, but will be appended to
#.
$arr7=array("color"=>array("favorite"=>"red"),5);
$arr8=array(10,array("favorite"=>"yellow","blue "));
print_r(array_merge_recursive($arr7,$arr8));
echo "

";
#array_reduce ( array $input , callback $function [, int $initial ]
#Apply the callback function iteratively to each unit in the input array, thereby simplifying the array
# into a single value. If the optional parameter initial is specified, the parameter will be treated as the
#th element in the array. A value to process, or as the final return value if the array is empty. If the array is empty and no initial parameter is passed, array_reduce() returns NULL
function rsum($v,$w){
$v+. =$w;
return $v;
}
function rmul($v,$w){
$v*=$w;
return $v;
}
$a=array(1,2,3,4 ,5);
$x=array();
$b=array_reduce($a,"rsum");
$c=array_reduce($a,"rmul",10);
$d=array_reduce($x ,"rsum",1);
echo $b."tt".$c."tt".$d."n";
echo "

";
#array_replace ( array &$array , array &$array1 [, array &$array2 [, array &$... ]] )
#Function replaces the value of the first array array with the value of the subsequent array element if a key exists. The first
# array also exists in the second array, and its value will be replaced by the value in the second array. If a
# key exists in the second array, but not in the first array, This
# element will be created in the first array.If a key only exists in the first array, it will remain unchanged. If multiple replacement number
#groups are passed, they will be processed in order, and subsequent arrays will overwrite the previous values.
$base=array("orange","banana","apple","raspberry");
$replacements=array(0=>"pineapple",4=>"cherry");
$replacements2 =array(0=>"grape");
#print_r(array_replace($base,$replacements,$replacements2));
#echo "

";
#array_splice ( array &$input , int $offset [, int $length [, array $ replacement ]] )
#Remove the units specified by offset and length in the input array. If the replacement
# parameter is provided, use the replacement array Unit replacement. Returns an array containing the removed cells
# . Note that numeric key names in input are not preserved. If length is omitted, all parts of the array from
# offset to the end are removed. If length is specified and is positive, this many cells are removed
# . If length is specified and is a negative value, all elements from offset to length
# inverse of the end of the array are removed. Tip: When replacement is given and you want to remove all cells from offset to
# the end of the array, use count($input) as length.
$input=array("red","green","blue","yellow");
array_splice($input,1,-1);
print_r($input);
echo "

";
#key ( array &$array )
#Return the key name of the current unit in the array.
$fruit=array("fruit1"=>"apple","fruit2"=>"orange","fruit3"=>"grape",
"fruit4"=>"apple","fruit5" =>"apple");
while($fruit_name=current($fruit)){
if($fruit_name=='apple'){
echo key($fruit)."
";
}
next($fruit);
}
echo "

";
?>

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