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Thread: QByteArray.split() returning QList with empty first element

  1. #1
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    Default QByteArray.split() returning QList with empty first element

    Hey Guys,

    I got a QByteArray containing some data. I distinguish different kinds of data via key characters which I prepend with a '&' character. Currently the data QByteArray only contians something like this: data = "&t02.04.2014".

    Qt Code:
    1. void foo(QByteArray data){
    2.  
    3. QList<QByteArray> cmdList = data.split('&');
    4.  
    5. if(cmdList.size() != data.count('&')) dispError("Command List size != number of '&'");
    6. //At this point the cmdList contains 2 elments where the first one is empty (presuming the data array is like noted above.
    7.  
    8. //do fancy stuff with the data
    9. }
    To copy to clipboard, switch view to plain text mode 

    I don't quite understand why there are two elments in the QList as I am only expecting one.

  2. #2
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    Default Re: QByteArray.split() returning QList with empty first element

    As a special character is treated as a marker for the end of the element. String "&&&aaa" gives You 4 elements.

  3. The following user says thank you to Lesiok for this useful post:

    FreddyKay (4th February 2015)

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    Default Re: QByteArray.split() returning QList with empty first element

    In other words "&" separates items. Therefore by definition the number of items in the array equals to number of separators + 1. Since you have one occurence of the separator, you have two items (no separators would yield one item -- the whole input string).
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

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  5. The following user says thank you to wysota for this useful post:

    FreddyKay (4th February 2015)

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    Default Re: QByteArray.split() returning QList with empty first element

    right. Gotcha. Thank you!

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    Default Re: QByteArray.split() returning QList with empty first element

    Take a look at the other split() arguments if you want to suppress empty sections.

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    Default Re: QByteArray.split() returning QList with empty first element

    Quote Originally Posted by ChrisW67 View Post
    Take a look at the other split() arguments if you want to suppress empty sections.
    QByteArray::split don't have other arguments, QString::split has them.

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    Default Re: QByteArray.split() returning QList with empty first element

    Having read the thread again I think the OP should use regular expressions rather than split.
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    Default Re: QByteArray.split() returning QList with empty first element

    Quote Originally Posted by wysota View Post
    Having read the thread again I think the OP should use regular expressions rather than split.
    And why is that?

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    Default Re: QByteArray.split() returning QList with empty first element

    Because you want to "distinguish" things rather than split columns. At least that's what I understood.
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    Default Re: QByteArray.split() returning QList with empty first element

    Quote Originally Posted by wysota View Post
    Because you want to "distinguish" things rather than split columns. At least that's what I understood.
    What I ultimatelly will have will be Array like this: [&t25.01.2015&satFancy Name//6000//Blablubb//something//42&antRunning//0//Illuminati&gs6300//2655].

    Each of the & indicates that the following stuff represents some values for objects that are specified by th name that follows '&'. The '//' seperate different values. Would it still be possible to use Regular Expressions? From first glance I figured split was what I wanted but you can teach me better

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    Default Re: QByteArray.split() returning QList with empty first element

    Yes, you can still use regular expressions.
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