CODEWITHSUNDEEP
stringstack-overflowrebolred-lang
rnso
rnso

Reputation: 24535

Replacing multiple occurrences of substring in Red language

I am trying to have a function that replaces multiple occurrences of oripart to newpart in the sent string: 

strReplace: func [str [string!] oripart [string!] newpart [string!]][
        if find str oripart [   
            change find str oripart newpart
            strReplace str oripart newpart ]  ; recursion to change more occurrences; 
        str ]

print strReplace "this is a short line" "short" "small"
print strReplace "this is a short line" "this" "THIS"
print strReplace "this is a short line" "line" "LINE"
print strReplace "this is a long line" "short" "small"
print strReplace "this is a short short line" "short" "small"

I am using recursion to remove multiple occurrences. It works all right for a single test line. However, it is producing stack overflow if I am testing above code. Where is the problem?

Upvotes: 0

Views: 77

Answers (1)

sqlab
sqlab

Reputation: 6436

Why you do not use just replace or replace/all

replace/all oristr oripart newpart

Your trial blows up because you change e.g. "this" to "THIS" and Red same as Rebol is mostly case insensitive, if you do not demand explicitly strict or case. So it recurses and recurses.

>> "this" = "THIS"
== true
>>  "this" == "THIS" 
== false
>> find "this"  "THIS"
== "this"

If you really want to use your own strReplace you should use find/case

>> find/case "this"  "THIS"
== none

There is one more solution to your problem; recurse at a position after the change as in

    strReplace: func [
        str [string!] oripart [string!] newpart [string!]
    ][
        if find str oripart [   
            str: change find str oripart newpart
            strReplace str oripart newpart   ; recursion to change more occurrences; 
        ]
        head str 
    ]

Upvotes: 3

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