How to delete certain strings in php

In PHP programming, string operation is one of the very important and common operations. Sometimes, we need to delete certain characters or strings in a string. In this case, PHP provides various built-in functions and methods to help us easily implement this operation.

Below, we will introduce several common ways to delete strings in PHP:

1. Use the str_replace() function

The str_replace() function is the most commonly used in PHP One of the string manipulation functions that can replace certain substrings in one string with another string. Of course, we can use an empty string ('') to replace the string that needs to be deleted to achieve the deletion operation.

For example, to remove all spaces from a string:

$str = 'This is a test string.';
$str = str_replace(' ', '', $str);
echo $str; //输出：Thisisateststring.

2. Use the preg_replace() function

The preg_replace() function is a powerful string manipulation function , which can use regular expressions to perform string replacement operations. Because regular expressions are very flexible, the preg_replace() function can adapt to various types of string matching and replacement needs.

For example, to remove some non-numeric characters from a string (only keep numbers):

$str = 'abc34de5fg_6789';
$str = preg_replace('/[^0-9]+/', '', $str);
echo $str; //输出：346789

In the above code, the regular expression "/¹ /" Means to match any non-numeric character (^ means negation, means match one or more times). Therefore, the preg_replace() function replaces all non-numeric characters with empty strings, thus achieving string deletion.

3. Use the substr() function

The substr() function can intercept a part of a string, and can also be used to delete a part of the string. We only need to specify the starting position and length that need to be deleted.

For example, to delete the first three characters from a string:

$str = 'This is a test string.';
$str = substr($str, 3);
echo $str; //输出：s is a test string.

4. Use the explode() and implode() functions

explode() function to The string is split into an array according to the specified delimiter, and the implode() function concatenates an array into a string according to the specified delimiter. Therefore, if we need to delete some strings, we can first split the string into an array, then delete the elements that need to be deleted from the array, and finally concatenate the array into a string.

For example, to remove all commas from a string:

$str = 'This, is, a, test, string.';
$arr = explode(',', $str);
$arr = array_filter($arr, function($v) { return $v != ','; });
$str = implode('', $arr);
echo $str; //输出：This is a test string.

In the above code, we first split the string into an array by commas, and then use the array_filter() function to filter out the commas elements, and finally concatenate the remaining array elements into a string.

Summary

The above are several ways to delete strings in PHP. Different methods are suitable for different situations and needs. In actual programming, we can choose the appropriate method to delete strings according to specific requirements.

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