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Escaping backslash in pcreReplace patterns

Driss

Hello Skill Community

I am getting into trouble when trying to escape backslash characters with PCRE expressions in skill.

My goal is to replace underscore characters in a given input string with   "\_" or sometimes with  "\\\_" 

So for instance:

inputSTR="TYP,Plan.3.Insertion_Loss_Fund_ATT0_TYP"
"TYP,Plan.3.Insertion_Loss_Fund_ATT0_TYP"

comPat1 = pcreCompile( "_" 0)
pcreobj@0x2e0be120

pcreReplace(comPat1 inputSTR "\\_" 0)
"TYP,Plan.3.Insertion_Loss_Fund_ATT0_TYP"

I put 2 blackslash characters in the last statement to escape its special meaning in Skill and would expect then this return: 

"TYP,Plan.3.Insertion\_Loss\_Fund\_ATT0\_TYP"

Similarly, if I would like to get 3 backslash in the end result, I would try this statement:

pcreReplace(comPat1 inputSTR "\\\\\\_" 0)

But skill returns:

"TYP,Plan.3.Insertion\\_Loss\\_Fund\\_ATT0\\_TYP"

as I would expect:

"TYP,Plan.3.Insertion\\\_Loss\\\_Fund\\\_ATT0\\\_TYP"

Can someone explain me where is my failure?

Thank you all in advance

Cedric

  • mbracht

    Hi Cedric,

    For each literal backslash in the result you need to specify 4(!) backslashes in your pcreReplace() call.
    So that creates one backslash:

    (pcreReplace (pcreCompile "_")  "A_B" "\\\\_" 0)

    ...and that one two:

    (pcreReplace (pcreCompile "_")  "A_B" "\\\\\\\\_" 0)

    Dont't let yourself get confused by the output in the CIW, literal backslashes as a return value are always indicated with another leading backslash:

    (pcreReplace (pcreCompile "_")  "A_B" "\\\\_" 0)
    "A\\_B"

    Just write the resulting string in a file and you will see that everything is as expected.

    Max

  • Driss
    in reply to mbracht

    Indeed, thanks for your answer!

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