operator = doesn't inherited from CTimeSpan class

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Hello all
After inheriting CTimeSpan class to my class CVoipTimeSpan the operater '=' is not inherited then i write the code to inheriting '=' operator as

C++

const CVoipTimeSpan& CVoipTimeSpan::operator=(const CVoipTimeSpan& entry)
{
    if (entry != *this)
    {
        (CTimeSpan)*this = (CTimeSpan) entry;
    }

    return *this;
}

i tested this code in following statements

C++

CTime curr_time;
CVoipTimeSpan time_span;
int time_diff_in_secs; 
curr_time = CTime::GetCurrentTime();
time_span = curr_time - database_cache_lookup_time;
time_diff_in_secs = time_span.GetTotalSeconds();

the operator '-' done correct and in time_deff_in_secs i got '0' why the operator = gives zero any modifications in my code please reply me .

Posted 5-May-11 3:09am

vallikelam

Updated 5-May-11 3:13am

Richard MacCutchan

v2

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Richard MacCutchan · Answer 1 · 2011-05-05T03:21:00

Solution 1

CTimeSpan::GetTotalSeconds() returns a LONG LONG value, but you are storing it to an int, this could be the problem. Try running your code through the debugger to see what value is being generated.

Posted 5-May-11 3:21am

Richard MacCutchan

Comments

vallikelam 5-May-11 9:28am

in my class CVoipTimeSpan i inherited all the members of CTimeSpan class and i typecasting all the functions to int when returning the functoions

Stefan_Lang 5-May-11 11:58am

Casting is almost always a very very bad idea. If you don't cast, errors like the one Richard pointed out will at least cause the compiler to throw a warning. By inserting a cast, all you do is tell the compiler that it shouldn't care - but you're still trying to measure a pool of water by pouring its contents into a small cup.

Richard MacCutchan 5-May-11 12:13pm

Well pointed out; I do find that far too many 'programmers' (and I use the word advisedly) think that casting actually offers some form of conversion.

fjdiewornncalwe 5-May-11 9:29am

Great catch. Like most devs I know, I got caught looking for subtleties instead of the "Is it plugged in" approach. +5

Sergey Alexandrovich Kryukov 5-May-11 18:45pm

Good catch, my 5. I also answered about operator, please see.
--SA

vallikelam 6-May-11 1:14am

I solved the negative values and defined the all constructors in my class that is not the problem only operator = doesn't inherited u said use argument (const CTimeSpan& entry) i also tried it but that doesn't taken it shows some ambiguous occurs i think some assignments are there i tried my best if u know please tell me

vallikelam 6-May-11 2:01am

Thank u sir for advising me i got the solution no need to define operator = in derived class it inherits = operator, why it didn't work long back when i tested i don't know, now i got the time_diff_in_secs.

Sergey Alexandrovich Kryukov · Answer 2 · 2011-05-05T12:44:00

Solution 2

You're trying to define operator for assigning CVoipTimeSpan to CVoipTimeSpan.
You need an operator to assign CVoipTimeSpan to CTimeSpan.

—SA

Posted 5-May-11 12:44pm

Sergey Alexandrovich Kryukov

Comments

Niklas L 6-May-11 2:46am

This is a very likely cause for trouble.