正则表达式替换双引号保持嵌套引号不变

Question

我希望将csv记录的每个双引号替换为其他字符，比如@#@，保持内部双引号不变。

例如，考虑以下记录

123453,"The NFL is promoting the importance of annual mammogram screenings for women over 40 in the prevention of breast cancer through their "A Crucial Catch" campaign.","Pittsburgh Steelers","NFL"

在这条记录中，我想用@#@替换每个字段开始和结束的双引号，这样它就变成了

123453,@#@The NFL is promoting the importance of annual mammogram screenings for women over 40 in the prevention of breast cancer through their "A Crucial Catch" campaign.@#@,@#@Pittsburgh Steelers@#@,@#@NFL@#@

请注意，"A Crucial“没有变化，因为它位于已经开始的双引号中

Answer 1

你可以搜索

"(?=,|$)|(?<=^|,)"

并用@#@替换它。此正则表达式查找逗号(或字符串的开头/结尾)前后的引号。

因此，在PHP中：

$result = preg_replace('/"(?=,|$)|(?<=^|,)"/', '@#@', $subject);

变化

123453,"The NFL is promoting "A Crucial Catch".","Pittsburgh Steelers","NFL"

转到

123453,@#@The NFL is promoting "A Crucial Catch".@#@,@#@Pittsburgh Steelers@#@,@#@NFL@#@

Answer 2

我增加了评论，因为你应该接受对你的问题有好答案的答案(我在那里看到了几个)……但这里有一个可能的解决方案：

<?php

$orig = '123453,"The NFL is promoting the importance of annual mammogram screenings for women over 40 in the prevention of breast cancer through their "A Crucial Catch" campaign.","Pittsburgh Steelers","NFL"';

$cols = explode(',', $orig);

function replace_end_quotes($val) {
    return preg_replace('#(^"|"$)#', "@#@", $val);
}

echo implode(",", array_map("replace_end_quotes", $cols));

正如@socha23在评论中提到的，如果其中一个字段中有逗号，我的解决方案将不起作用。但是，如果上面的代码行实际上被格式化为有效的CSV数据，那么使用诸如str_getcsv之类的代码代替explode就可以了。

Answer 3

为什么不遍历文件并创建一个字符串来重建this。

虽然效率不是很高，但你可以尝试……

$out = "";

if (($handle = fopen("test.csv", "r")) !== FALSE) {
    while (($data = fgetcsv($handle, 1000, ",")) !== FALSE) {
        $arr = array();
        for ($i = 0; $i < count($data); $i++) {
            if (!ctype_digit($data[$i])) {
                $data[$i] = '@#@' . $data[$i] . '@#@';
            }
            $arr[] = $data[$i];
        }
        $out .= implode("", $arr) . "\n";
    }
    fclose($handle);
}

// Write $out to file or whatever