How to clear non-numeric elements in an array in php

In PHP development, array is a very important data type. We may need to clear all non-numeric elements in the array in order to perform more complex calculations or other operations.

This article will introduce how to use PHP to clear non-numeric elements in an array, and provide some practical examples to help readers better understand this process.

1. Use the PHP built-in function array_filter()

The array_filter() function can traverse the array and delete elements that do not meet the conditions. We can use this function to filter an array through a custom function, retaining only numeric elements. The following is a code example:

$array = array("string", 1234, "5", "67.8", 90);

function only_num($var)
{
    return is_numeric($var);
}

$result = array_filter($array, "only_num");

print_r($result);  //输出：Array ( [1] => 1234 [2] => 5 [3] => 67.8 [4] => 90 )

In the above example, we use the is_numeric() function, which determines whether the given variable is a number or a numeric string. We then pass this function as a callback function to the array_filter() function to process the array.

2. Using regular expressions

Regular expressions are a very useful text processing tool that can be used to match and replace text with a certain pattern. In this case, we can use regular expressions to match all numbers and remove non-number elements.

The following is an example of a regular expression for cleaning an array:

$array = array("string", 1234, "5", "67.8", 90);

foreach ($array as $key => $value) {
    if (preg_match('/^\d+$/',$value) !== 1) {
        unset($array[$key]);
    }
}

print_r($array);  //输出：Array ( [1] => 1234 [2] => 5 [4] => 90 )

In the above example, we use the preg_match() function and the regular expression "/^\d $/" to match all numeric string. If the match is successful (1 is returned), the element is a number. Otherwise, we will call the unset() function to delete the element. Finally, we output the remaining numeric elements to the screen.

3. Using the array_walk() function

The array_walk() function is another PHP built-in function that can be used to traverse an array and perform a custom function on each element. We can use this function to clear non-numeric elements from an array.

The following is an example of using the array_walk() function to clean an array:

$array = array("string", 1234, "5", "67.8", 90);

function only_num(&$value, $key)
{
    if (!is_numeric($value)) {
        unset($value);
    }
}

array_walk($array, "only_num");

print_r($array);  //输出：Array ( [1] => 1234 [2] => 5 [3] => 67.8 [4] => 90 )

In the above example, we pass the callback function to the array_walk() function to clear the non-numeric elements. When the element is not a number, we remove it so that only numeric elements remain.

Conclusion

In PHP development, the use of arrays is very common. Sometimes, we need to remove all non-numeric elements from an array in order to perform complex calculations or other operations. This article describes three different ways to achieve this goal: using the PHP built-in function array_filter(), using regular expressions, and using the array_walk() function. You can choose different methods according to your own needs, and modify and adjust them according to the actual situation. In actual development, this technique should be very useful.

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