Check if multiple strings exist in another string

Question

How can I check if any of the strings in an array exists in another string?

Like:

a = ['a', 'b', 'c']
str = "a123"
if a in str:
  print "some of the strings found in str"
else:
  print "no strings found in str"

That code doesn't work, it's just to show what I want to achieve.

Answer 1

You can use any:

if any(x in str for x in a):

Similarly to check if all the strings from the list are found, use all instead of any.

Answer 2

You need to iterate on the elements of a.

a = ['a', 'b', 'c']
str = "a123"
found_a_string = FALSE
for item in a:    
    if a in str:
        found_a_string = TRUE

if found_a_string:
    print "found a match"
else:
    print "no match found"

Answer 3

a = ['a', 'b', 'c']
str =  "a123"

a_match = [True for match in a if match in str]

if True in a_match:
  print "some of the strings found in str"
else:
  print "no strings found in str"

Answer 4

You should be careful if the strings in a or str gets longer. The straightforward solutions take O(S*(A^2)), where S is the length of str and A is the sum of the lenghts of all strings in a. For a faster solution, look at Aho-Corasick algorithm for string matching, which runs in linear time O(S+A).

Answer 5

You shouldn't use str as a name:

>>> str(7)
'7'
>>> str = 'joe'
>>> str(7)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'str' object is not callable