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Introduction to commonly used array functions in PHP_PHP tutorial
- WBOYOriginal
- 2016-07-13 10:21:42764browse
Introduction to commonly used array functions in PHP
How can you program without arrays? The following are the array processing functions commonly used when learning PHP. One principle to follow in programming is the DRY (Don`t Repeat Yourself) principle. There are a large number of functions in PHP. It is not practical to remember these functions, but commonly used functions still need to be used skillfully. The use of most functions Methods can be used by consulting the PHP manual.
It is indispensable to consult manuals in programming, so you must learn to use existing things. For example, the array processing function in PHP already has a sorting function. Why bother to write something that is fake? Soak or stack or quick queue.
Programming is an indirect process and a process of reuse. To write good code, design patterns are indispensable for support. It may be difficult for beginners to learn design patterns (just like when I first looked at design patterns, It’s a bit laborious), but when you have accumulated a certain amount of code, when you study design patterns, you feel that design patterns are really useful and can help you write beautiful code. Having said that, I got a little off track, so let’s summarize the commonly used functions for array operations in PHP.
Some readers may feel that the commonly used functions for arrays summarized below are a bit lacking. Will the flames be high if everyone adds firewood? If you feel that there are other commonly used array processing functions, please leave a comment. Don’t be stingy with your knowledge. , isn’t it a very happy thing to share things with others? Also, the code below is from my own hand, but it was written two years ago. Everyone is welcome to criticize and correct me.
array_splice() deletes the specified element in the array
Array_splice (array name, number of items to delete from front to back, new size of an array); without the third parameter, there is no returned array. When there is no third parameter, the meaning of the second parameter is from front to back. Keep a few
exp:
$my_array=array( //Create an array
"hehe"=>"haha",
"A"=>"lu",
"lu"=>"ge"
);
$new=array_splice($my_array,1,3); //Use array_splice (array name, number of items to delete from front to back, new size of an array);
var_dump($new);
?>
Result: array(2) { ["A"]=> string(2) "lu" ["lu"]=> string(2) "ge" }
2. Traversal of foreach() array
Usage: foreach (array as key name => key value) or foreach (array as key value)
exp:
$my_array=array( //Create an array
"hehe"=>"haha",
"A"=>"lu",
"lu"=>"ge"
);
foreach($my_array as $key=>$value)
{
echo $key."=>".$value."
";
}
?>
Output result:
hehe=>haha
A=>lu
lu=>ge
3. Sorting of arrays
(1)sort() and rsort() sort by key value sort() from small to large, rsort() from large to small
sort () exp :
$my_array=array(1,2,3,6,7,8,9,4,5);//Create an array
sort($my_array);
foreach($my_array as $keys=>$value)
{
echo $keys."=>".$value."
";
}
?>
Output result:
0=>1
1=>2
2=>3
3=>4
4=>5
5=>6
6=>7
7=>8
8=>9
rsort() exp:
$my_array=array(1,2,3,6,7,8,9,4,5);//Create an array
rsort($my_array);
foreach($my_array as $keys=>$value)
{
echo $keys."=>".$value."
";
}
?>
Output result:
0=>9
1=>8
2=>7
3=>6
4=>5
5=>4
6=>3
7=>2
8=>1
(2).asort() and arsort() have the same principle as above, but do not change the corresponding relationship between key names and key values
exp:
$my_array=array(1,2,3,6,7,8,9,4,5);//Create an array
asort($my_array);
foreach($my_array as $keys=>$value)
{
echo $keys."=>".$value."
";
}
?>
Output result:
0=>1
1=>2
2=>3
7=>4
8=>5
3=>6
4=>7
5=>8
6=>9
(3)ksort() and krsort() are sorting by key name
4. Mathematical functions of arrays
array_sum() calculates the sum of all key values in the array count() calculates the number of elements
exp:
$my_array=array(1,2,3,6,7,8,9,4,5);//Create an array
echo array_sum($my_array);
?>
Output result: 45
5. Other functions
array_unique() removes the same elements in the array
in_array() checks whether a value is in the array (returns true and false)
Array_search() returns the key or value, and returns the key name corresponding to the key value
shuffle() disrupts the original array
$my_array=array(1,2,3,6,7,8,9,4,5,5,5,5);//Create an array
array_unique($my_array);//Remove the same elements in the array
var_dump($my_array);
echo "
";
echo in_array(5,$my_array);
echo "
";
$new=array_search(6,$my_array);//Returns the key name corresponding to the key value
echo $new;
?>
Output result:
array(12) { [0]=> int(1) [1]=> int(2) [2]=> int(3) [3]=> int(6) [4 ]=> int(7) [5]=> int(8) [6]=> int(9) [7]=> int(4) [8]=> int(5) [9 ]=> int(5) [10]=> int(5) [11]=> int(5) }
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