How to use PHP regular expressions to convert matched characters or strings into an array

In PHP programming, regular expressions are a very powerful tool that can be used to process strings, match patterns and other operations. When processing strings, we often need to extract characters or strings that match a certain pattern and then combine them into an array or string. This article will introduce how to use PHP regular expressions to convert matched characters or strings into arrays and output them.

1. Use the preg_match_all function to match strings

preg_match_all is a function in PHP used to match multiple strings. It can match all qualified characters or strings in a string according to the specified regular expression, and save them in an array and return them. The syntax of the preg_match_all function is as follows:

int preg_match_all ( string $pattern , string $subject , array &$matches [, int $flags = PREG_PATTERN_ORDER [, int $offset = 0 ]] )

Among them, $pattern represents the regular expression to be matched, and $subject represents the string to be matched. $matches is an incoming array parameter used to store the matched string, that is, the output array. $flags is an optional parameter used to set the matching mode. $offset indicates where in the string to start matching.

The following is an example of the preg_match_all function:

$str = "my name is Jack, Jack is my name";
$pattern = "/Jack/";
preg_match_all($pattern, $str, $matches);
print_r($matches);

The output result is as follows:

Array
(
    [0] => Array
        (
            [0] => Jack
            [1] => Jack
        )

)

It can be seen from the results that the preg_match_all function has matched the regular expression in the string $str The strings of the formula "/Jack/" are matched and stored in the $matches array.

2. Convert array output

Next, the obtained array needs to be converted and output. It is recommended to use the foreach statement to traverse the array and output values ​​that meet the conditions.

$str = "my name is Jack, Jack is my name";
$pattern = "/Jack/";
preg_match_all($pattern, $str, $matches);
foreach ($matches[0] as $val) {
    echo $val."\n";
}

The above code will output the following results:

Jack
Jack

By looping through the obtained array and outputting it, the final result is to convert the matched characters or strings into an array for output.

3. Implement the complete code

The following is a complete sample code, which will find all the numbers in the string and store them in an array and return them.

$str = "1 apple, 2 oranges and 3 bananas";
preg_match_all('/\d+/', $str, $matches);
foreach ($matches[0] as $num) {
    $arr[] = $num;
}
print_r($arr);

The output result of this sample code is:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
)

IV. Summary

This article mainly introduces how to use PHP regular expressions to convert matched characters or strings into an array and output. The specific implementation method is to use the preg_match_all function to match the string and store it in an array, and then loop through the obtained array and output it. The final result is to convert the matched characters or strings into an array for output. When using regular expressions, it is recommended to learn more about their usage and common syntax, so that you can use regular expressions to process strings and text more flexibly and efficiently.

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