From: Chris Rebert on 10 May 2010 19:31 On Mon, May 10, 2010 at 4:25 PM, AON LAZIO <aonlazio(a)gmail.com> wrote: > As subject says, what is the differences of 'is not' and '!='. Confusing.. != checks value inequality, `is not` checks object identity / "pointer" inequality Unless you're doing `foo is not None`, you almost always want !=. By way of demonstration (using the non-negated versions to be less confusing): >>> x = [1, 2] >>> y = [1, 2] >>> x == y True >>> x is y False >>> z = x >>> x is z True >>> z is y False >>> x.append(3) >>> x [1, 2, 3] >>> y [1, 2] >>> z [1, 2, 3] >>> x is z True Cheers, Chris -- http://blog.rebertia.com
From: Christian Heimes on 10 May 2010 19:32 AON LAZIO wrote: > As subject says, what is the differences of 'is not' and '!='. Confusing.. "is not" checks if two objects are not identical. "!=" checks if two objects are not equal. Example: Two apples may be equal in size, form and color but they can never be identical because they are made up from different atoms. Christian
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