Question

Using python, create a program using nested loops to write a function called substring(s,b) that returns True or False depending on whether or not b is a substring of s.

For example:

String: "Diamond"

Substring: "mond"

The code will then state that this is true and "mond" is a substring of "Diamond".

Example of what the program should output:

Enter string: Tree

Enter substring: Tre

Yes, 'Tre' is a substring of 'Tree'

Limitation: This program cannot use "find()" and "in" functions or generally anything from the string library. This program has to be a nested loop.

Answer 1

def substring(s, b):
    for i in range(len(s) - len(b) + 1):
        found = True
        for j in range(len(b)):
            if s[i+j] != b[j]:
                found = False
        if found:
            return True
    return False


s = input("Enter string: ")
b = input("Enter substring: ")

if substring(s, b):
    print("Yes, '{}' is a substring of '{}'".format(b, s))
else:
    print("No, '{}' is not a substring of '{}'".format(b, s))