当两个字符序列之间出现时，替换/删除特定字符的最佳方法

Question

我有一个PHP函数，该功能从2个不同字符序列之间的字符串中选择文本。

function get_string_between($string, $start, $end){
    $string = ' ' . $string;
    $ini = strpos($string, $start);
    if ($ini == 0) return '';
    $ini += strlen($start);
    $len = strpos($string, $end, $ini) - $ini;
    return substr($string, $ini, $len);
}

$fullstring = ',""Word1, Word2""';
$parsed = get_string_between($fullstring, ',""', '""');

echo $parsed; //Result = Word1, Word2

但是，我想进一步扩展此内容，以选择字符串中有多个出现时的所有匹配项（这很可能，因为字符串将由具有数百行和数百个匹配的CSV文件生成。

$fullstring = ',""Word1, Word2"" and another thing ,""Word3, Word4""';

）在每个子弦中，我需要删除某些字符。在此示例中，我需要删除逗号。

预期的输出将是：

//Result2 = ',""Word1 Word2"" and another thing ,""Word3 Word4""'

任何人都可以提出实现这一目标的最直接方法吗？谢谢。

Answer 1

因此，我要求输出这是一件好事，因为最初我还有其他东西。许多人会在这里使用正则表达式，但是我经常发现很难使用，所以我采用了一种更基本的方法：

function extractWantedStuff($input)
{
    $output = [];
    $sections = explode('""', $input);
    $changeThisSection = false;
    foreach ($sections as $section) {
        if ($changeThisSection) {
            $section = str_replace(',', '', $section);
        }
        $output[] = $section;
        $changeThisSection = !$changeThisSection;
    }
    return implode('""', $output);
}

$fullstring = ',""Word1, Word2"" and another thing ,""Word3, Word4""';

echo extractWantedStuff($fullstring);

输出将是：

,""Word1 Word2"" and another thing ,""Word3 Word4""

示例代码

通过删除$ changethissection布尔值：

function extractWantedStuff($input)
{
    $output = [];
    $sections = explode('""', $input);
    foreach ($sections as $key => $section) {
        if ($key % 2 != 0) { // is $key uneven?
            $section = str_replace(',', '', $section);
        }
        $output[] = $section;
    }
    return implode('""', $output);
}

$fullstring = ',""Word1, Word2"" and another thing ,""Word3, Word4""';

echo extractWantedStuff($fullstring);

示例代码

并通过删除$ output数组：

function extractWantedStuff($string)
{
    $sections = explode('""', $string);
    foreach ($sections as $key => $section) {
        if ($key % 2 != 0) {
            $sections[$key] = str_replace(',', '', $section);
        }
    }
    return implode('""', $sections);
}

$fullstring = ',""Word1, Word2"" and another thing ,""Word3, Word4""';

echo extractWantedStuff($fullstring);

示例代码

Answer 2

实际上，您可以以start和end substrings以非贪婪的方式执行匹配所有字符，并使用 preg_match_all 捕获如下所示的所有这些中间字符串：

<?php

$fullstring = ',""Word1, Word2"" and another thing ,""Word3, Word4"",""Word5, Word6""';
$start = ',""';
$end = '""';
preg_match_all('/'. preg_quote($start) . '(.+?)' . preg_quote($end) . '/', $fullstring, $matches);
print_r($matches[1]);

在线演示

更新：

如果您希望执行整个单词匹配，您可以简单地进行贪婪的匹配，以？使用 preg_match 喜欢下面：

<?php

$fullstring = ',""Word1, Word2"" and another thing ,""Word3, Word4"",""Word5, Word6""';
$start = ',""';
$end = '""';
preg_match('/'. preg_quote($start) . '(.*)' . preg_quote($end) . '/', $fullstring, $matches);
print_r($matches[0] ?? []);

Answer 3

您可以简单地使用字符串替换函数，如果您要删除特定的字符串，我只是将这些功能传递给数组中并用Blanck空间代替。

function removeExtraCharacters($fullstring, $characters = array()){
    foreach($characters as $char){
        $fullstring = str_replace($char,"", $fullstring);
    }
    return $fullstring;
}
$fullstring = ',""Word1, Word2"" and another thing ,""Word3, Word4""';
echo removeExtraCharacters($fullstring, array(',"', '"'));
//output: Word1, Word2 and another thing Word3, Word4