douyazi1129
douyazi1129
2014-11-08 21:10

php简单的正则表达式搜索和替换和随机子串

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i have a string to be used for latex later the string is... roughly

$string  = "\\sin\\left(x\ight)^{2}";

where the sin could also be cos, tan, sec, log, etc.. the exponent could also be any integer, float or variable, the argument could be anything..

I would like a regex function that turns it into

$string  = "\\sin^{2}\\left(x\ight)";

or more generally

generalstring = "f(t)^{n}";

to be turned into "f^{n}(t)"; my apologies in advance, i have a feeling this should be extremely easy to do, I'm just learning this.

oh also i would like to restric this to only strings with trig functions logs and some other ones where my functions are not printing correctly.

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2条回答

  • douxie9471 douxie9471 7年前

    Please try the following code:

    $string = preg_replace('/\\\\(\w+)\\\\left\\((.+?)\\\ight\\)\\^\\{([^}]+)\\}/','\\\\$1^{$3}\left($2ight)',$string);
    

    For me, the output is:

    print "$string
    ";
    
    \sin^{2}\left(xight)
    

    Another test:

    $string  = "\\cos\\left(3x\ight)^{2.6}";
    

    Output:

    \cos^{2.6}\left(3xight)
    

    It also works for multiple functions, since preg_replace is global per default.

    $string = "\\sin\\left(x\ight)^{3}\\cos\\left(y\ight)^{2}";
    
    \sin^{3}\left(xight)\cos^{2}\left(yight)
    

    Edit: Please note the corrected expression.

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  • dtujfmfs06058 dtujfmfs06058 7年前

    A regex like

    (\\{2}sin|cos|tan|sec|log)([^^]*)(\^\{[^}]*\})
    

    see how the regex matches http://regex101.com/r/iW4pZ3/1

    The replacement string is \\1\\3\\2

    preg_replace("/(\\\\{2}sin|cos|tan|sec|log)([^^]*)(\\^\\{[^}]*\\})/","\\1\\3\\2","\\\\sin\\\\left(x\\\ight)^{2}");
    

    would produce an output as

    \\sin^{2}\\left(x\ight)
    
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