Exception hadling in c++

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Hi
NOTE:: Sorry it is very basic question if you reply would be very nice

what i am trying to do is while reading text from file. splitting the text with ( : ). But if some line in the file has no : than want to throw error. and in the catch section display msg wrong text format.
sample text in file is
Text part 1 : Text Part 2 //line 1
text part 1 : text part 2 //line 2
text part 1 : text part 2 //line 3
sample text without colon //line 4 line without :

  try{
    QStringList Textfields = TextLine.split(":");
    TextFirstPart = Textfields [0];
    TextSecPart = Textfields [1];
throw;
}
catch(...)
{
cout <<"Unidntified Input data format"<<endl;
}

trying to throw error msg only for line 4. How to do this??

What I have tried:

i tried what i mentioned above but it is not working....

Posted 6-Mar-16 21:37pm

KhalBuz

Updated 6-Mar-16 22:19pm

v2

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2 solutions

Solution 1

In order to make it working, you should remove the throw; statement. In any case you might avoid using exceptions, in such a simple scenario: using the QStringList's size method, you are able to detect the 'unidentified inpup data format' line.

Posted 6-Mar-16 21:52pm

CPallini

Comments

KhalBuz 7-Mar-16 3:55am

I am using exception. because there is one more scenario in which i need to handle
e.g
string text : string text // line 1
some digit : string text //both should be strings if its digit than also throw error
I want to throw error if any unexpected text line will come. there are many different possibilities so rather than going for complex if else if else i am trying to throw error msg of "unexpected data input". this is my understanding your suggestions are welcome

Philippe Mori 7-Mar-16 13:17pm

Usually, you don't want to do that... It is a misuse of exceptions to used them as a replacement of conditionà statements. Exception should only be used for exceptionnal error condition.

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Jochen Arndt · Accepted Answer · 2016-03-06T22:19:00

Just check if splitting was possible. If there was no ':' character, the string is not splitted and the list contains only one element (the original string):

C++

if (TextFields.count() == 1)
    throw;

But in your case there is no need to use exceptions because you are detecting and handling the error inside your function. Instead you might use an error indicator and return that from your function:

C++

int error = 0;
while (!error && !EndOfFile())
{
    QString TextLine = ReadLine();
    QStringList Textfields = TextLine.split(":");
    if (TextFields.count() == 1)
    {
        // No ':' character
        error = 1;
    }
    else if (TextFields.count() > 1)
    {
        // Multiple ':' characters
        error = 2;
    }
    // Check for other errors here
    else
    {
        // Process line
    }
}
if (error)
{
    // Show error message
}
// Return false when an error occured
return 0 == error;