Python simply traverses the dictionary and removes elements

This example shows how Python can simply traverse a dictionary and delete elements. I will share it with you for your reference as follows:

There must be something wrong with this approach:

d = {'a':1, 'b':2, 'c':3}
for key in d:
  d.pop(key)

This error will be reported: RuntimeError: dictionary changed size during iteration

Python2 works this way, but Python3 still reports the above error.

d = {'a':1, 'b':2, 'c':3}
for key in d.keys():
  d.pop(key)

The reason Python3 is reporting an error is that the keys() function returns dict_keys instead of list. Possible ways of Python3 are as follows:

d = {'a':1, 'b':2, 'c':3}
for key in list(d):
  d.pop(key)

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I hope this article is helpful to you Python programming.