Example of php implementing array processing method

1. Split the string into an array:

$array=explode(separator,$string)：

separator: separator,

$string: split string;

2. Combine the array into String:

$string=implode(glue,$array)：

glue: glue character,

$array: array;

3. The length of statistical array: count():

count The function has two parameters:
0 (or COUNT_NORMAL) is the default, which does not detect multi-dimensional arrays (arrays within arrays);
1 (or COUNT_RECURSIVE), which detects multi-dimensional arrays

<?php$arr=array(                 
0=>array(&#39;title&#39; => &#39;苹果&#39;, &#39;viewnum&#39; => 青的, &#39;content&#39; => &#39;pingguo&#39;),                 
1=>array(&#39;title&#39; => &#39;柚子&#39;, &#39;viewnum&#39; => 红心, &#39;content&#39; => &#39;youzi&#39;)               
);
 
echo &#39;不统计多维数组：&#39;.count($arr,0);//count($arr,COUNT_NORMAL)echo "<br/>";echo &#39;统计多维数组：&#39;.count($arr,1);//count($arr,COUNT_RECURSIVE)?>

4, merge Two arrays: array_merge():

$a[];
$b[];
$c[] = array_merge( $a , $b );

5. Array sorting:

• sort() - Sort the array in ascending order

• rsort() - Sort an array in descending order

• asort() - Sort an associative array in ascending order based on value

• ksort() - Sorts an associative array in ascending order by key

• arsort() - Sorts an associative array in descending order by value

• krsort() - Sorts an associative array in descending order based on key

The array_multisort() function sorts multiple arrays or multidimensional arrays.

<?php
$a1=array(1,30,15,7,25);
$a2=array(4,30,20,41,66);
$num=array_merge($a1,$a2);
array_multisort($num,SORT_DESC,SORT_NUMERIC);
print_r($num);
?>

6. Conversion between array and json format:
json_encode(): Convert the array into json object format, add parameters: JSON_UNESCAPED_UNICODE to encode Chinese;

json_decode(): Convert json object to php object format;

##json_decode( $obj , true ): Convert the json object into an array;

$bad_json = "{ 'bar': 'baz' }";
$bad_json = '{ bar: "baz" }';
$bad_json = '{ "bar": "baz", }'

Executing json_decode() on these three strings will return null and report an error.

The first mistake is that the json delimiter only allows the use of double quotes, not single quotes. The second mistake is that the "name" of the json name-value pair (the part to the left of the colon) must be used in double quotes under any circumstances. The third error is that you cannot add a trailing comma after the last value.

In addition, json can only be used to represent objects and arrays. If json_decode() is used on a string or value, null will be returned.

7. Intersection, difference, and union of arrays

$inter_arr = array_intersect($m_arr,$m_card)：数组的交集；
             $diff_arr = array_diff($m_card,$m_arr)：数组的差集；

The difference set of arrays can only obtain the differences in the first array that are not in other arrays. If you want to obtain the differences of all arrays Set combination array_merge();

$diff_arr = array_diff($m_card,$m_arr);
$diff_arr2 = array_diff($m_arr,$m_card);
$arr = array_merge($diff_arr,$diff_arr2);
 
$merge = array_merge()：数组的并集；

8. Replace the value of the array:

array_replace();

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