Occurence of characters in common in two strings

Question

I want to use a for loop to calculate the number of times a character in one string occurs in another string.

e.g. if string1 = \'python\' and string2 = \'b

Answer 1

Use dict comprehension {ch:string2.count(ch) for ch in string1 if ch in string2}

I forgot you need a for loop and sum over all letters.

count = 0 
for ch in string1:
    if ch in string2:
        count += string2.count(ch)

Answer 2

Pretty straightforward:

count = 0

for letter in set(string1):
  count += string2.count(letter)

print(count)