Intersection of php arrays

Php array intersection

I can't quite understand these methods in the manual. Which of the following experts can explain?

Array_intersect (array1, array2) // Obtain the intersection of the comparison values.
Array_intersect_assoc () // The intersection of the comparison key name and value
Array_intersect_key (array1, array2) // The intersection of comparison key names

The two below are not very clear
Array_intersect_uassoc (array1, array2, array3., function)
Array_intersect_ukey (array1, array2, array3., function)

What is the function return value?

It is better to give an example in practice.

Reply to discussion (solution)

The function parameter indicates that the value or key value in an array, such as array1, array2, and array3, will execute this function.

function  key_compare_func ( $key1 ,  $key2 ){    if ( $key1  ==  $key2 )        return  0 ;    else if ( $key1  >  $key2 )        return  1 ;    else        return - 1 ;} $array1  = array( 'blue'   =>  1 ,  'red'   =>  2 ,  'green'   =>  3 ,  'purple'  =>  4 ); $array2  = array( 'green'  =>  5 ,  'blue'  =>  6 ,  'yellow'  =>  7 ,  'cyan'    =>  8 ); var_dump ( array_intersect_ukey ( $array1 ,  $array2 ,  'key_compare_func' ));

Output result:
Array (2 ){
["Blue"] =>
Int (1)
["Green"] =>
Int (3)
}
These examples are available in the php Manual.

To solve the intersection problem of two arrays, use array_intersect (), array_inersect_assoc, and array_intersect_key. the array_intersect () function is used to calculate the intersection of two numbers.

 "Red","green"=>"red4","Red15"=>"Red",7=>"Level","Width"=>"Red","azzzz1"=>"art","peak"=>158); $array1 = array("red"=>"Red2","greena"=>"red","Red15"=>"Red",7=>"Level","Width"=>"Red","azzzz"=>"art","peak"=>158); $num = array_intersect($array,$array1); print_r ($num); echo ""; $num = array_intersect_assoc($array,$array1); print_r($num); echo ""; $num = array_intersect_key($array,$array1); print_r ($num); ?>

See http://web10000.cn/thread-126-1-1.html for details
Hope to help you

Take the code of #1 as an example.

function  key_compare_func ( $key1 ,  $key2 ) {    if ( $key1  ==  $key2 )        return  0 ;    else if ( $key1  >  $key2 )        return  1 ;    else        return - 1 ;} $array1  = array( 'blue'   =>  1 ,  'red'   =>  2 ,  'green'   =>  3 ,  'purple'  =>  4 );$array2  = array( 'green'  =>  5 ,  'blue'  =>  6 ,  'yellow'  =>  7 ,  'cyan'    =>  8 );print_r( array_intersect_key ( $array1 ,  $array2 ));print_r( array_intersect_ukey ( $array1 ,  $array2 ,  'key_compare_func' ));

Get

Array(    [blue] => 1    [green] => 3)Array(    [blue] => 1    [green] => 3)

We can see that array_intersect_key uses functions equivalent to key_compare_func internally.
Array_intersect_ukey can change the default behavior through the callback function.

function  key_compare_func ( $key1 ,  $key2 ) {    if ( strtolower($key1)  ==  strtolower($key2) )        return  0 ;    else if ( $key1 > $key2 )        return  1 ;    else        return - 1 ;} $array1  = array( 'Blue'   =>  1 ,  'red'   =>  2 ,  'green'   =>  3 ,  'purple'  =>  4 );$array2  = array( 'green'  =>  5 ,  'blue'  =>  6 ,  'yellow'  =>  7 ,  'cyan'    =>  8 );print_r( array_intersect_key ( $array1 ,  $array2 ));print_r( array_intersect_ukey ( $array1 ,  $array2 ,  'key_compare_func' ));

Array(    [green] => 3)Array(    [Blue] => 1    [green] => 3

We can see that the comparison is no longer case sensitive.

Take the code of #1 as an example.

function  key_compare_func ( $key1 ,  $key2 ) {    if ( $key1  ==  $key2 )        return  0 ;    else if ( $key1  >  $key2 )        return  1 ;    else        return - 1 ;} $array1  = array( 'blue'   =>  1 ,  'red'   =>  2 ,  'green'   =>  3 ,  'purple'  =>  4 );$array2  = array( 'green'  =>  5 ,  'blue'  =>  6 ,  'yellow'  =>  7 ,  'cyan'    =>  8 );print_r( array_intersect_key ( $array1 ,  $array2 ));print_r( array_intersect_ukey ( $array1 ,  $array2 ,  'key_compare_func' ));

Get

Array(    [blue] => 1    [green] => 3)Array(    [blue] => 1    [green] => 3)

We can see that array_intersect_key uses functions equivalent to key_compare_func internally.
Array_intersect_ukey can change the default behavior through the callback function.

function  key_compare_func ( $key1 ,  $key2 ) {    if ( strtolower($key1)  ==  strtolower($key2) )        return  0 ;    else if ( $key1 > $key2 )        return  1 ;    else        return - 1 ;} $array1  = array( 'Blue'   =>  1 ,  'red'   =>  2 ,  'green'   =>  3 ,  'purple'  =>  4 );$array2  = array( 'green'  =>  5 ,  'blue'  =>  6 ,  'yellow'  =>  7 ,  'cyan'    =>  8 );print_r( array_intersect_key ( $array1 ,  $array2 ));print_r( array_intersect_ukey ( $array1 ,  $array2 ,  'key_compare_func' ));

Array(    [green] => 3)Array(    [Blue] => 1    [green] => 3

We can see that the comparison is no longer case sensitive.

Array_intersect_ukey.
The array_intersect_uassoc function, in the manual, says: "Note: What is different from array_intersect_assoc () is the comparison of key values and key names, function only compares values. The comparison of keys is not mentioned.

function  key_compare_func ( $key1 ,  $key2 ) {    if ( strtolower($key1)  ==  strtolower($key2) )        return  0 ;    else if ( $key1 > $key2 )        return  1 ;    else        return - 1 ;} $array1  = array( 'Blue'   =>  1 ,  'red'   =>  2 ,  'green'   =>  3 ,  'purple'  =>  4 );$array2  = array( 'blue'  =>  1 ,  'green'  =>  5 ,  'yellow'  =>  7 ,  'cyan'    =>  8 );print_r( array_intersect_assoc ( $array1 ,  $array2 ));print_r( array_intersect_uassoc ( $array1 ,  $array2 ,  'key_compare_func' ));

Array()Array(    [Blue] => 1)

See it?

function  key_compare_func ( $key1 ,  $key2 ) {    if ( strtolower($key1)  ==  strtolower($key2) )        return  0 ;    else if ( $key1 > $key2 )        return  1 ;    else        return - 1 ;} $array1  = array( 'Blue'   =>  1 ,  'red'   =>  2 ,  'green'   =>  3 ,  'purple'  =>  4 );$array2  = array( 'blue'  =>  1 ,  'green'  =>  5 ,  'yellow'  =>  7 ,  'cyan'    =>  8 );print_r( array_intersect_assoc ( $array1 ,  $array2 ));print_r( array_intersect_uassoc ( $array1 ,  $array2 ,  'key_compare_func' ));

Array()Array(    [Blue] => 1)

See it?
How can we differentiate whether the function parameter is a 'key' or a 'value '?

No need to differentiate
Array_intersect_uassoc uses the callback function to identify the key.

To determine the value and key, use the array_uintersect_uassoc function.
And pass two callback functions

No need to differentiate
Array_intersect_uassoc uses the callback function to identify the key.

To determine the value and key, use the array_uintersect_uassoc function.
And pass two callback functions

Austria understands. Thank you!