qstring.mid() questions

Ok, I can't figure out why this is not working:

Code:

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QString temp_vol_id = temp_string;
int first_dot = temp_string.indexOf(".");
int last_dot = temp_string.lastIndexOf(".");
QString temp_name = temp_string.mid((first_dot+1),((last_dot-first_dot)-1))

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where temp_vol_id = a valid 82 char qstring
first_dot = 47
last_dot = 61

the debugger states temp_name is <invalid>
I attempted changing qstring.mid second parameter to -1 (it should extract from
first_dot to end of string, but that also returns <invalid>

I am using similar statements in other sections of the code successfully.
Can anyone see anything incorrect in this snippet of code?

thanks

John

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Added after 5 minutes:

I should have included the complete function for clarity:

Code:

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QString Widget::get_Vol_ID(QString temp_string)
{
    QString temp_vol_id = temp_string;
    int first_dot = temp_vol_id.indexOf(".");
    int last_dot = temp_vol_id.lastIndexOf(".");
    QString temp_name1 = temp_vol_id.mid((first_dot+1),((last_dot-first_dot)-1));
  //  QString temp_name = temp_vol_id.mid(first_dot,-1);
 //   QString temp_name = temp_vol_id.mid((first_dot+1),((last_dot-first_dot)-1));
    QString temp_noise = "";
    return(temp_name1);
 
}

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you can see the commented out lines that were attempted (without success)

thanks

John

Hm, there is no error in the code. It works well on my side. Please add

Code:

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qWarning() << Q_FUNC_INFO << temp_vol_id << first_dot << last_dot;

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before the return of your function and post the output in the cases where it do not work like expected.