I am writing a program in python, it's very simple I just want to know how to make make the input from a user true if it only contains m, u or i in it but absolutely nothing else. my code runs but if the input is 'miud' it will return true because m i and u are in it. the code below is what I have so far, how can I change it to make it allow only the letters m u and i?
x=input("Enter your string")
if 'm' in x and 'i' in x and 'u' in x:
print("true")
else:
print("false")
You can use a set for that,
if set(x).issubset({'m', 'u', 'i'}):
print("true")
else:
print("false")
This code makes use of sets and the issubset method. Since a string is an iterable so it can be used as an argument to set(). The set will contain unique items (in this case each unique character from the input string).
That value can be tested against the known valid characters (also in a set) with the issubset method.
{'m', 'u', 'i'} is one way of creating a set, but this would work too:
if set(x).issubset(set('mui')):
Use all built-in.
string = input("Enter your string")
print(all(char in ['m', 'i', 'u'] for char in string))
Basically,
(char in ['m', 'i', 'u'] for char in string)
builds an iterable that yields booleans. For each char in the string (starting from the first), this iterator yields True if the char is m, i or u, False otherwise.
Then you feed all() this iterator:
all(iterable)Return True if all elements of the iterable are true (or if the iterable is empty). Equivalent to:
def all(iterable): for element in iterable: if not element: return False return True
all iterates over the newly created iterator and returns False as soon as it gets a False, or True if it gets only True values.
The beauty of iterators is that no True / False list is ever computed: the tests are done on the fly and all stops as soon as a char is found that is not neither of m, i, or u. Not relevant here, but this can have a performance impact in some applications.
