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Pattern Matching of Regular Expressions

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I’m studing this topic and I met problem to understand this example…
 
rexCompile("\\([a-z]+\\)\\.\\1")        => t
rexExecute("abc.bc")                    => t
rexExecute("abc.ab")                    => nil
 
It is not clear why the second case is nil and if I type:
 
rexCompile("\\([a-z]+\\)\\.\\1")        => t
rexExecute("abc.bc")                    => t
 
rexSubstitute( “debug: \\0" ) => debug: bc.bc
 
Why the result is bc.bc?
 
 \1 register should not point to abc?
 
Please, could you clarify me how it works? Where could I find accurate information as the cdsdoc is not clear on how registers work.
 
Giuseppe

 


Originally posted in cdnusers.org by Giuseppe Greco
Parents

  • Ok, perhaps I do not understand how it works...

    rexCompile("\\([a-z]+\\)\\.\\1") ; => t
    ok,

    If I do rexExecute("abc.bc")

    \1 should contain the value matched by \([a-z]+)\, ok? In our case it should be "abc". It is correct?
    I would expect our rexCompile should be equivalent to

    rexCompile("[a-z]+\\.abc")

    so

    rexExecute("abc.bc") => nil

    and

    rexExecute("abc.ab") => nil

    Why the first is true??

    >>stand for :" search any pattern that match 'blablablaXXXX.XXXX'

    Could you explain hot to interpret rexCompile("\\([a-z]+\\)\\.\\1") ?

    Thank you,

    Giuseppe


    Originally posted in cdnusers.org by Giuseppe Greco
Reply

  • Ok, perhaps I do not understand how it works...

    rexCompile("\\([a-z]+\\)\\.\\1") ; => t
    ok,

    If I do rexExecute("abc.bc")

    \1 should contain the value matched by \([a-z]+)\, ok? In our case it should be "abc". It is correct?
    I would expect our rexCompile should be equivalent to

    rexCompile("[a-z]+\\.abc")

    so

    rexExecute("abc.bc") => nil

    and

    rexExecute("abc.ab") => nil

    Why the first is true??

    >>stand for :" search any pattern that match 'blablablaXXXX.XXXX'

    Could you explain hot to interpret rexCompile("\\([a-z]+\\)\\.\\1") ?

    Thank you,

    Giuseppe


    Originally posted in cdnusers.org by Giuseppe Greco
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