Well i'm takign an array
IE
I'm just wondering if i am doing this correctly, i'm not at stage in my project were i can realy test it.Code:int number[4] = { 1, 0 , 2 ,3 } ; then i pass it to my function Number Number::operator= (int *theNumber) { int **localNumber = &theNumber; }
IF i am doing it right could you guys suggest a better way to do it.
Thanks
Last edited by Iamien; 01-09-2004 at 11:28 PM.
Whilst what you wrote is valid, I doubt it's what you want.
Describe in words what you want
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
since i posted this i think i got it the way i want it
What i wanted was to be able to set the value of a member of my class by overlaoding the equals operator, which would take an array of int and make the value of the member equal to it.
the problem i was having was i wans't sure how to take the passed variable, assign it to a local variable, and do it properly. this is what i ended up with
Code:void Number::operator= (const int *theNumber) { const int *localNumber = theNumber; int currentPos = 0 ; while ( localNumber[currentPos] != NULL ) { currentPos++; } Number::Size = currentPos + 1; Number::Value = new int[Number::Size]; currentPos = 0; while ( currentPos < Number::Size ) { Number::Value[currentPos] = localNumber[currentPos]; currentPos++; } Number::Value[currentPos] = NULL; }
Several errors.
1) const int *localNumber = theNumber;
No need for this.
2) while ( localNumber[currentPos] != NULL ) {
This won't work. NULL is an invalid value to compare against integers (though it unfortunatly compiles in C++), and you argument array is not guaranteed to be 0-terminated. In fact the example array from your post isn't. You would have to pass a second argument containing a size, but since that doesn't work with operator =, the function won't work out. You could pass a std::vector though.
3) Number::Value = new int[Number::Size];
Possible memory leak. What about this code?
After the first assignment, Value is a pointer to dynamic memory. In the second, this pointer gets overwritten by the next allocation, and the old memory is a leak.Code:Number n; int ar[4] = {1, 2, 3, 4}; n = ar; n = ar;
4) while ( currentPos < Number::Size ) {
A memcpy would be much faster.
5) Number::Value[currentPos] = NULL;
Assignment of NULL to int is no more valid than comparison. Besides, what if there is a 0 in the normal array? You class will think the number ends there.
All the buzzt!
CornedBee
"There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
- Flon's Law
Thanks. i had already fixxed the NULL termination problem, as my array will only be hold numbers between 0-9 i terminate it with a 10. going over what you said, and fixing what i can.
Thanks
