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I cannot get the command cmp() to work.
Here is the code:
a = [1,2,3] b = [1,2,3] c = cmp(a,b) print (c) I am getting the error:
Traceback (most recent call last): File "G:\Dropbox\Code\a = [1,2,3]", line 3, in <module> c = cmp(a,b) NameError: name 'cmp' is not defined [Finished in 0.1s] 
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cmp() does not work in python 3. You might want to see list comparison in Python. Practical Application: Program to check if a number is even or odd using cmp function. Approach: Compare 0 and n%2, if it returns 0, then it is even, else its odd.
The __cmp__() special method is no longer honored in Python 3. In Python 2, __cmp__(self, other) implemented comparison between two objects, returning a negative value if self < other , positive if self > other , and zero if they were equal.
The cmp() function The cmp(x,y) function compares the values of two arguments x and y − cmp(x, y) The return value is − A negative number if x is less than y. Zero if x is equal to y.
cmp was removed because the key attribute to . sort() and sorted() is superior in most cases. It was a hold-over from C more than anything, and was confusing to boot. Having to implement a separate __cmp__ method next to the rich comparison operators ( __lt__ , __gt__ , etc.)
As mentioned in the comments, cmp doesn't exist in Python 3. If you really want it, you could define it yourself:
def cmp(a, b): return (a > b) - (a < b) which is taken from the original What's New In Python 3.0. It's pretty rare -- though not unheard of -- that it's really needed, though, so you might want to think about whether it's actually the best way to do whatever it is you're up to.
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