CODEWITHSUNDEEP
regextcl
Puneet Mittal
Puneet Mittal

Reputation: 542

string substitution regular expression not working in tcl

i am trying to replace all the special characters including white space, hyphen, etc, to underscore, from a string variable in tcl.

Example

    input: Stack Overflow helps%me(a lot
    output: Stack_Overflow_helps_me_a_lot

I wrote the code below but it doesn't seem to be working. 

    set varname $origVar
    puts "Variable Name :>> $varname"
    if {$varname != ""} {
        regsub -all {[\s-\]\[$^?+*()|\\%&#]} $varname "_" $newVar
    }
    puts "New Variable :>> $newVar"

one issue is that, instead of replacing the string in $varname, it is deleting the data after first space encountered inside $origVar instead of $varname. Also there is no value stored in $newVar. No idea why, and also i read the example code (for proper syntax) in my tcl book and according to that it should be something like this

    regsub -all {[\s-][$^?+*()|\\%&#]} $varname "_" newVar

so i used the same syntax but it didn't work and gave the same result as modifying the $origVar instead of required $varname value.

Upvotes: 1

Views: 3958

Answers (2)

Andrew Cheong
Andrew Cheong

Reputation: 30283

The second version is closer. By putting the result in $newVar you're actually setting a variable named whatever is stored in $newVar, i.e. you would then have to access it by $$newVar, so to speak (not valid in Tcl). Anyway, the issue is probably that in your second version, you don't seem to be escaping certain characters. Try this:

regsub -all {[\s\-\]\[$^?+*()|\\%&#]} $varname "_" newVar

Another way to organize that to minimize escaping is this:

regsub -all {[][\s$^?+*()|\\%&#-]} $varname "_" newVar

And, I don't know if this is too general, but you can try this too:

regsub -all {\W} $varname "_" newVar

Upvotes: 3

Hai Vu
Hai Vu

Reputation: 40763

Another solution is to use the string map command, which is simpler: the string map command takes in a list of old/new and a string:

set varname [string map {% _ ( _ " " _} $varname]

In the above example, for the sake of brievity, I only replaced %, (, and space " " with an underscore. The disadvantage of this solution is the old/new list can be somewhat long. The advantage is easier to understand.

Upvotes: 2

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