Calculate difference in keys contained in two Python dictionaries

Question

Suppose I have two Python dictionaries - dictA and dictB. I need to find out if there are any keys which are present in dictB but not

Answer 1

If on Python ≥ 2.7:

# update different values in dictB
# I would assume only dictA should be updated,
# but the question specifies otherwise

for k in dictA.viewkeys() & dictB.viewkeys():
    if dictA[k] != dictB[k]:
        dictB[k]= dictA[k]

# add missing keys to dictA

dictA.update( (k,dictB[k]) for k in dictB.viewkeys() - dictA.viewkeys() )