Perl：不替换字符串

Question

如果我使用类似这样的简单方法替换另一个字符串

my $pet = "I have a dog.";
my $search = "dog";
my $replace = "cat";
$pet =~ s/$search/$replace/;

它工作正常，我得到“我有一只猫。”正如预期的那样。

但是当我使用更复杂的东西时，它不会被替换：

my $image_correction_hash = {};

$device = "my_device";
$correction_hash->{$device}->{'to_be_replaced'} = "174_4492_232313_7078721ec0.jpg";

# my json string
my $json = '[{"credits":[],"issue":174,"layout":"special_cover","text":[],"hide_overline":"","category":"Kunst","id":"174_4492","media_data":[{"thumbnail":"","data_is_cover":1,"subheadline":"","value":"174_4492.jpg","type":"image","headline":""},{"data_position":"left","thumbnail":"","subheadline":"","value":"174_4492_232302_3980b3da34.jpg","data_effect":"smear","type":"image","headline":""},{"data_position":"right","thumbnail":"","subheadline":"","value":"174_4492_232313_7078721ec0.jpg","data_effect":"smear","type":"image","headline":""}],"links":[],"textmarker":"","teaser":"","hide_headline":"","article_thumbnail":"174_4492_article_thumbnail.jpg","subheadline":"","gallery":[],"overline":"","headline":"Covertitel\n"}]';


print STDERR "JSON string before:" . $json . "\n";

foreach my $search ( keys %{$correction_hash->{$device}})
{
    print STDERR "to be replaced:".$correction_hash->{$device}->{$search}.".\n";

    # the replacement
    $json =~ s/$search/XXXXX/g;
}
print STDERR "JSON string after:" . $json . "\n"; # no replacement occured - GRRR

这里的错误在哪里？

Answer 1

你混淆了变量。

试试这个：

print STDERR "to be replaced:".$search.".\n";

它会打印这个：to be replaced:to_be_replaced.

所以你可以使用这个代码：

my $pattern = $correction_hash->{$device}->{$search};
$json =~ s/$pattern/XXXXX/g;

附带说明，如果您的 $pattern 不是正则表达式，您应该使用以下代码对其进行转义：

$json =~ s/\Q$pattern\E/XXXXX/g;

Answer 2

您尝试在模式替换中使用$search，而不是您要替换的实际模式。所以你试图用XXXXXXXX 替换to_be_replaced。不是174_4492_232313_7078721ec0.jpg。

您可能想要添加：

  $replace_pattern = $correction_hash->{$device}->{$search};
  $json =~ s/$replace_pattern/XXXXX/g;