Gsub导致部分字符串被替换

Question

I want to replace all occurrences of a single quote ( ' ) with backslash single quote ( \\' ). I tried doing this with gsub , but I'm getting partial string duplication:

a = "abc 'def' ghi"
a.gsub("'", "\\'")
# => "abc def' ghidef ghi ghi"

Can someone explain why this happens and what a solution to this is?

Answer 1

It happens because "\\\\'" has a special meaning when it occurs as the replacement argument of gsub , namely it means the post-match substring.

To do what you want, you can use a block:

a.gsub("'"){"\\'"}
# => "abc \\'def\\' ghi"

Notice that the backslash is escaped in the string inspection, so it appears as \\\\ .

Answer 2

Your "\\\\'" actually represents a literal \\' because of the backslash escaping the next backslash. And that literal \\' in Ruby regex is actually a special variable that interpolates to the part of the string that follows the matched portion . So here's what's happening.

abc 'def' ghi
    ^

The caret points to the first match, ' . Replace it with everything to its right, ie def' ghi .

abc def' ghidef' ghi
    ++++++++

Now find the next match:

abc def' ghidef' ghi
               ^

Once again, replace the ' with everything to its right, ie ghi .

abc def' ghidef ghi ghi
               ++++

Answer 3

It's possible you just need a higher dose of escaping:

a.gsub(/'/, "\\\\'" )

Result :

abc \\'def\\' ghi