Match sub-string within a string with tolerance of 1 character mismatch - Stack Overflow

Match sub-string within a string with tolerance of 1 character mismatch - Stack Overflow

Question - Amazon Interview Quesion

Write a function in C that can find if a string is a sub-string of another. Note that a mismatch of one character should be ignored.

A mismatch can be an extra character: ’dog’ matches ‘xxxdoogyyyy’ 
A mismatch can be a missing character: ’dog’ matches ‘xxxdgyyyy’
A mismatch can be a different character: ’dog’ matches ‘xxxdigyyyy’

The return value wasn't mentioned in the question, so I assume the signature of the function can be something like this:

char * MatchWithTolerance(const char * str, const char * substr);

If there is a match with the given rules, return the pointer to the beginning of matched substring within the string. Else return null.

A more generic way of making the tolerance to n instead of 1, then that would be just brilliant. In that case the signature would be:

char * MatchWithTolerance(const char * str, const char * substr, unsigned int tolerance = 1);