n00b string replace

[theistian]

Hi I'm triying to substitute any ocurrences of ' in a string by \'

Here's a bit of testing I made in irb which wtf's me:

irb(main):002:0> st = "un ' monton ' de ' apostrofes '"
=> "un ' monton ' de ' apostrofes '"
irb(main):003:0> sst = st.gsub(/'/,"\'")
=> "un ' monton ' de ' apostrofes '"

ok substitute ' by ' I don't know why interpeter interpret \' as
' when in a double-quoted string contex but I'm a newbie so sure I'm
wrong

irb(main):004:0> sst = st.gsub(/'/,"\\'")
=> "un monton ' de ' apostrofes ' monton de ' apostrofes ' de
apostrofes ' apostrofes "
irb(main):005:0> sst = st.gsub(/'/,"\\\'")
=> "un monton ' de ' apostrofes ' monton de ' apostrofes ' de
apostrofes ' apostrofes "

This seems to be substitute ' by "rest of string from ocurrence"
regardless of scape chars

Totally dazzed and desperate I tried with another backslash.... who
cares ... and get this

irb(main):006:0> sst = st.gsub(/'/,"\\\\'")
=> "un \\' monton \\' de \\' apostrofes \\'"

How do I get "un \' monton \' de \' apostrofes \'" from "un ' monton '
de ' apostrofes '"? using regex?

Thanks

 

[Jon Evans]

Hi,

How do I get "un \' monton \' de \' apostrofes \'" from "un ' monton '
de ' apostrofes '"? using regex?

Like this:
=> "un \\' monton \\' de \\' apostrofes \\'"

It just displays with \\ in there because it needs to escape the \
itself when displaying it. Any manipulations you need to do on the
actual string object will only see a single '\' character rather than
a double.

s = "'" => "'"
s.gsub!(/'/, "\\\\'") => "\\'"
s.length => 2
s[0].chr => "\\"
s[1].chr

=> "'"

Jon