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Language/Type: VB recursion string return

Write a recursive function named NonMatching that accepts two strings as parameters, and returns an integer representing the number of character indexes between the two strings that do not match. For this problem, two strings are defined as having a "match" at a given index if they contain exactly the same ASCII character value at that index. For example, consider the following two strings:

' index     012345678901234
Dim s1 As String = "I love Mariana!"
Dim s2 As String = "U Love Marty"

In the above example, seven indexes do not match (underlined above for emphasis): indexes 0, 2, 10, 11, 12, 13, and 14. So the call of NonMatching(s1, s2) would return 7 . Any character could match or fail to match, including letters, numbers, spacing, punctuation, etc. Your function is case-sensitive notice that the "l"c and "L"c at index 2 do not match.

If the two strings are not the same length, any indexes at the end of the longer string by definition do not match, since there is no character in the other string at that index that could correspond to them. One implication of this is that if one of the parameters is an empty string, the entirety of the other string is considered non-matching.


  • Do not use any loops you must use recursion.
  • Do not declare any global variables.
  • Do not call any string member functions or string library functions that traverse or search the entire string. (The point of this problem is to solve it recursively do not use a library function to get around recursion.)
  • Do not use any auxiliary data structures like List, Dictionary, etc. You can declare as many primitive variables like integers as you like, as well as strings.
  • You are allowed to define other "helper" functions if you like they are subject to these same constraints.
Function: Write a VB function as described, not a complete program.

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