N00b string replace

ruby-talk
1

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 ' :stuck_out_tongue: 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

2

Hi,

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

Like this:

st = "un ' monton ' de ' apostrofes '"

=> "un ' monton ' de ' apostrofes '"

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

=> "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

路路路

On Apr 30, 12:22 pm, theist...@gmail.com wrote:

3

You can really confuse the heck out of yourself this way. There are two
problems:

(1) Backslashes must be escaped in a double-quoted string.

(2) gsub has special behavior unlike anything else in Ruby: backslashes
are unescaped in the second parameter, regardless of the quoting.

So, if you want one backslash to be substituted, and if you insist on
double-quoting, you have to type *four* backslashes:

irb(main):003:0> puts "hello".gsub("e","\\\\")
h\llo

For the workaround, check this recent thread:

<http://groups.google.com/group/comp.lang.ruby/browse_thread/thread/d8f4
74e7f2959585/9cadabc099a27925?lnk=st&q=#9cadabc099a27925>

m.

路路路

<theistian@gmail.com> wrote:

irb(main):003:0> sst = st.gsub(/'/,"\'")

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