


A brief discussion of PHP source code 18: About array_diff_key, array_diff_assoc, array_udiff_assoc functions
This article mainly introduces the eighteenth chapter of PHP source code: About array_diff_key, array_diff_assoc, array_udiff_assoc functions, which have certain reference value. Now I share them with you. Friends in need can refer to them
Talking about PHP source code 18: About array_diff_key, array_diff_assoc, array_udiff_assoc function
[array_diff_key]
(PHP 5 >= 5.1.0RC1)
array_diff_key — Use key name comparison to calculate the array Difference set
Description
array array_diff_key (array array1, array array2 [, array ...])
array_diff_key() returns an array that includes all occurrences in array1 But the value of the key does not appear in any other parameter array. Note that the relationship remains unchanged.
【array_diff_assoc】
(PHP 4 >= 4.3.0, PHP 5)
array_diff_assoc — Calculates the difference of an array with index checking
Description
array array_diff_assoc ( array array1, array array2 [, array ...] )
array_diff_assoc() Returns an array that includes all values in array1 but not in any other parameter array. Note that unlike array_diff(), key names are also used for comparison.
The reason why these three functions are put together is because the last function they call is one function: php_array_diff_key
[array_diff_uassoc]
(PHP 5)
array_diff_uassoc — Use user The provided callback function does index checking to calculate the difference set of the array
Description
array array_diff_uassoc (array array1, array array2 [, array ..., callback key_compare_func] )
array_diff_uassoc( ) returns an array containing all values in array1 that are not in any other parameter array.
The way these three functions call php-array_diff_key is as follows:
1 |
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The macro definition of the parameters is as follows:
1 |
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The php_array_diff_key function first needs to be based on the incoming data_compare_type (i.e. The three macros defined above), determine the comparison function to be used, then traverse the first array, compare each element with other arrays to see if other numbers exist
If they exist, delete them
For An explanatory note on the source code of this function:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 |
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About the comparison function:
DIFF_COMP_DATA_NONE parameter corresponds to NULL, that is, there is no comparison, just use the index search
DIFF_COMP_DATA_INTERNAL The parameter corresponds to zval_compare, that is, both the index and the value will be compared.
DIFF_COMP_DATA_USER The parameter corresponds to zval_user_compare, which is a user-defined function.
The above is the entire content of this article. I hope it will be useful for everyone's learning. For help, please pay attention to the PHP Chinese website for more related content!
Related recommendations:
A brief discussion on PHP source code 16: About the array_count_values function
A brief discussion on PHP source code 15: About the array_walk function
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