如何去掉多余的双引号？

在格式错误的 .csv 文件中，有一行数据带有额外的双引号，例如最后一行：

Name,Comment
"Peter","Nice singer"
"Paul","Love "folk" songs"

如何删除周围的双引号folk并将字符串替换为：

Name,Comment
"Peter","Nice singer"
"Paul","Love _folk_ songs"

在 Ruby 1.9 中，可以执行以下操作：

result = subject.gsub(/(?<!^|,)"(?!,|$)/, '_')

以前的版本没有lookbehind断言。

解释：

(?<!^|,)  # Assert that we're not at the start of the line or right after a comma
"         # Match a quote
(?!,|$)   # Assert that we're not at the end of the line or right before a comma

当然，这是假设我们不会遇到像这样的病理情况

"Mary",""Oh," she said"