A program that PHP merges the values of 2 numeric key arrays

Source: Internet
Author: User
Tags arrays numeric

First you need to understand a basic knowledge point

Two arrays in PHP can be combined with + or array_merge, but there is a difference, and if you don't know the difference, it's going to kill you!
The main difference is that if the same key name appears in two or more arrays, the key name is divided into strings or numbers, which requires attention
1 when the key name is a number, the value following the Array_merge () will not overwrite the original value, but append to the back, but the + merge array will return the first occurrence of the value as the final result, and those values that have the same key name in the following array "Discard" (not overwrite)
2 when the key name is a string, Array_merge () overrides the value of the same key name in front of it, but the + still returns the first occurrence of the value as the final result, and those values that have the same key name in the following array are "discarded" (not overwritten).

The code is as follows Copy Code

$a = Array (' A ', ' B ');
$b = Array (' C ', ' d ');
$c = $a + $b;
Var_dump ($a);
Var_dump (Array_merge ($a, $b));

Output:

Array
0 => string ' a ' (length=1)
1 => string ' B ' (length=1)

Array
0 => string ' a ' (length=1)
1 => string ' B ' (length=1)
2 => string ' C ' (length=1)
3 => string ' d ' (length=1)

++++++++++++++++++++++++++++++++++++++++++

$a = Array (
0 => ' a ',
1 => ' B '
);
$b = Array (
0 => ' C ',
1 => ' B '
);
$c = $a + $b;
Var_dump ($c);
Var_dump (Array_merge ($a, $b));

Output:

Array
0 => string ' a ' (length=1)
1 => string ' B ' (length=1)

Array
0 => string ' a ' (length=1)
1 => string ' B ' (length=1)
2 => string ' C ' (length=1)
3 => string ' B ' (length=1)

++++++++++++++++++++++++++++++++++++++++++

$a = Array (' A ', ' B ');
$b = Array (
' 0 ' => ' C ',
1 => ' B '
);
$c = $a + $b;
Var_dump ($c);
Var_dump (Array_merge ($a, $b));

Output:
Array
0 => string ' a ' (length=1)
1 => string ' B ' (length=1)

Array
0 => string ' a ' (length=1)
1 => string ' B ' (length=1)
2 => string ' C ' (length=1)
3 => string ' B ' (length=1)

++++++++++++++++++++++++++++++++++++++++++

$a = Array (
0 => ' a ',
1 => ' B '
);
$b = Array (
' 0 ' => ' C ',
' 1 ' => ' B '
);
$c = $a + $b;
Var_dump ($c);
Var_dump (Array_merge ($a, $b));

Output:

Array
0 => string ' a ' (length=1)
1 => string ' B ' (length=1)

Array
0 => string ' a ' (length=1)
1 => string ' B ' (length=1)
2 => string ' C ' (length=1)
3 => string ' B ' (length=1)

All right, so much for you. Let's take a look at the value of merging 2 numeric key arrays

The code is as follows Copy Code

<?php
/**
* PHP merges the values of 2 numeric key arrays
*
* @param array $arr 1
* @param array $arr 2
* @return Array
* @author www.111cn.net
*/
function New_array_merge ($arr 1, $arr 2)
{
$arr = Array_flip ($arr 1) + Array_flip ($arr 2);
Return Array_keys ($arr);
}

$arr 1 = array (' AA ', ' BB ', ' cc ');
$arr 2 = Array (' Aa2 ', ' BB ', ' cc2 ');

$arr = New_array_merge ($arr 1, $arr 2);
Print_r ($arr);

Output:

Array
(
[0] => AA
[1] => BB
[2] => cc
[3] => Aa2
[4] => CC2
)

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.