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Asked: 2026-05-13T18:12:03+00:00

In the following code, if the string s is appended to be something like

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In the following code, if the string s is appended to be something like 10 or 20 thousand characters, the Mathematica kernel seg faults.

s = "This is the first line.
MAGIC_STRING
Everything after this line should get removed.
12345678901234567890123456789012345678901234567890123456789012345678901234567890
12345678901234567890123456789012345678901234567890123456789012345678901234567890
12345678901234567890123456789012345678901234567890123456789012345678901234567890
12345678901234567890123456789012345678901234567890123456789012345678901234567890
12345678901234567890123456789012345678901234567890123456789012345678901234567890
...";

s = StringReplace[s, RegularExpression@"(^|\\n)[^\\n]*MAGIC_STRING(.|\\n)*"->""]

I think this is primarily Mathematica’s fault and I’ve submitted a bug report and will follow up here if I get a response. But I’m also wondering if I’m doing this in a stupid/inefficient way. And even if not, ideas for working around Mathematica’s bug would be appreciated.

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1 Answer

  1. Editorial Team

    Mathematica uses PCRE syntax, so it does have the /s aka DOTALL aka Singleline modifier, you just prepend the (?s) modifier before the part of the expression in which you want it to apply.

    See the RegularExpression documentation here: (expand the section labeled “More Information”)
    http://reference.wolfram.com/mathematica/ref/RegularExpression.html

    The following set options for all regular expression elements that follow them:
    (?i) treat uppercase and lowercase as equivalent (ignore case)
    (?m) make ^ and $ match start and end of lines (multiline mode)
    (?s) allow . to match newline
    (?-c) unset options

    This modified input doesn’t crash Mathematica 7.0.1 for me (the original did), using a string that is 15,000 characters long, producing the same output as your expression:

    s = StringReplace[s,RegularExpression@".*MAGIC_STRING(?s).*"->""]

    It should also be a bit faster for the reasons @AlanMoore explained

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