Convert Microsoft Curly Quotes to Straight Quotes in PHP

Question

I am having a really hard time trying to fix a Clients Database records. I need to Find and Replace all Curly Quotes which look like this “ with Straight Quotes "

Attempt 1
I have tried to run this on my MySQL database with no luck.

update wp_posts set post_content = replace(post_content,'“','"');

Attempt 2
I have also tried search and replace in PHP with the below, with no luck as well

<?php
$str = ' “evil curly quotes“ no "good straight quotes"';
str_replace ('“', '"', $str);

echo $str;

// Prints:
// “evil curly quotes“ no "good straight quotes"
?>

Please help me anyone, there has to be an easy way to do this besides manually editing thousands of records?

Answer 1

You are not actually replacing any value. You forgot to assign the return value of the str_replace call to the $str variable. This will do the trick:

<?php
$str = ' “evil curly quotes“ no "good straight quotes"';
$str = str_replace ('“', '"', $str);

echo $str;

// Prints:
// “evil curly quotes“ no "good straight quotes"
?>

edit: Tom D also provided the correct answer in his comment (and did it earlier than me to be fair).

Answer 2

// Replace smart or curly quotes, dashes and ellipses
// Replace UTF-8 characters.
$string = str_replace(
array("\xe2\x80\x98", "\xe2\x80\x99", "\xe2\x80\x9c", "\xe2\x80\x9d", "\xe2\x80\x93", "\xe2\x80\x94", "\xe2\x80\xa6"),
array("'", "'", '"', '"', '-', '--', '...'),
$string);
// Replace Windows-1252 equivalents.
$string = str_replace(
array(chr(145), chr(146), chr(147), chr(148), chr(150), chr(151), chr(133)),
array("'", "'", '"', '"', '-', '--', '...'),
$string);