What may be the cause of following error?

[pratik041]

@ASSERT failure in QList<T>::at: "index out of range"@

[A Former User]

I believe you are passing an index position that doesn't exist. I mean for example that your QList has only five elements and you are trying to access the sixth.

const T & QList::at ( int i ) const

Returns the item at index position i in the list. i must be a valid index position in the list (i.e., 0 <= i < size())

[pratik041]

[quote author="Josué V. Herrera" date="1324275775"]I believe you are passing an index position that doesn't exist. I mean for example that your QList has only five elements and you are trying to access the sixth.

const T & QList::at ( int i ) const

Returns the item at index position i in the list. i must be a valid index position in the list (i.e., 0 <= i < size())[/quote]
ok thanks i will check it.

[lgeyer]

Worth mentioning that you'll see mainly two behaviours with Qt containers (as for example QList):

• at() and operator[] asserts on invalid indices,
• value() does not assert on invalid indices, it returns a default-constructed value instead.

If you use both your code may or may not assert, depending on which method you use, even though your code causes acccess to an invalid index.

[dangelog]

Watch out, operator[] does assert!

[Chris H]

Right: the difference isn't the lack of assertions (both methods have them) -- the difference is the copy functionality. From the documentation: "at() can be faster than operator, because it never causes a deep copy to occur."