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PHP array learning: change the uppercase or lowercase of keys/values

Aug 12, 2021 pm 06:38 PM
php Case array key value Key name

In the previous article, we introduced the method of deleting any element in the array. If you are interested, you can click on the link to view → "php Array Learning: How to Remove Any Element". This time we will learn how to change the case of array key names or key values ​​in PHP associative arrays. Interested friends can learn about it~

First of all, let’s take a look atHow to change the case of array key names or key values ​​in PHP associative arrays Change the key value to uppercase or lowercase , we have an array like this:

$fruits = array('A' => 'Apple', 'B' => 'Banana', 'c' => 'Cherry', 'o' => 'Orange');
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We convert all the array element values ​​​​in it to uppercase:

 $value){
	$fruits[$key]=strtoupper($value);
}
echo "转换为大写后:";
var_dump($fruits);
?>
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Use the foreach statement to traverse $fruits array, use the strtoupper($value) function in the loop to convert the array element $value to uppercase, so the output result is:

PHP array learning: change the uppercase or lowercase of keys/values

Conversion Converting to lowercase is similar to converting to uppercase. You only need to replace the strtoupper() function with the strtolower() function. The strtolower() function can convert a string to lowercase.

 $value){
	$fruits[$key]=strtolower($value);
}
echo "转换为小写后:";
var_dump($fruits);
?>
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The output result is:

PHP array learning: change the uppercase or lowercase of keys/values

To sum up, encapsulate it into a function that converts upper and lower case:

 $value){
			//如果$case值为CASE_UPPER则,
			if($case==CASE_LOWER){
				$array[$key]=strtolower($value);
			}else if($case==CASE_UPPER){
				$array[$key]=strtoupper($value);
			}
		}
    }
	return $array;
}
$fruits = array('A' => 'Apple', 'B' => 'Banana', 'c' => 'Cherry', 'o' => 'Orange');
$lower=array_change_value_case($fruits,CASE_LOWER);
var_dump($lower);
$upper=array_change_value_case($fruits,CASE_UPPER);
var_dump($upper);
?>
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Designarray_change_value_case ($array,$case)The function supports two required parameters $array and $case, where the $case parameter has two values: CASE_LOWER (convert to lowercase letters) and CASE_UPPER (convert to uppercase letters).

Let’s take a look at the above output:

PHP array learning: change the uppercase or lowercase of keys/values

Okay, we already know the key-value conversion method, let’s take a look at the key How to convert a name to uppercase or lowercase ?

Manipulating the case of array key names in PHP is not as complicated as controlling the case of key values ​​above. PHP directly provides a function that converts array key names to uppercase letters or lowercase letters-array_change_key_case(). Let’s take a look at how to use it:

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Analysis: array_change_key_case($array ,$case) function supports 1 required parameter $array and 1 omitted parameter $case (control case, default value is CASE_LOWER). $case has two values ​​:

  • CASE_LOWER - Default value. Convert an array's keys to lowercase letters.

  • CASE_UPPER - Converts an array's keys to uppercase letters.

So the output result is:

PHP array learning: change the uppercase or lowercase of keys/values

Okay, that’s all. If you want to know anything else, you can click this . → →php video tutorial

Finally, I would like to recommend a free video tutorial on PHP arrays: PHP function array array function video explanation, come and learn!

The above is the detailed content of PHP array learning: change the uppercase or lowercase of keys/values. For more information, please follow other related articles on the PHP Chinese website!

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