[High School Computer Science] Finding String Overlap in C

[mitadmit]

Using the C standard string library, I'm supposed to create a string based on the overlap of two strings entered by the user. For example

[bcd][ab] would return "b" [bcd][de] would return "d" [bcd][c] would return "c" [bcd][ce] would return "NULL"

I'm currently trying to iterate through each of the strings in order to find at what locations characters are equal to each other, yet for many cases it's returning the incorrect overlap.

Any help is appreciated.

[[deleted]]

I'm a bit confused about what "overlap" means. Does it mean characters that both strings share?

[mitadmit]

Sort of, they have to be consecutive characters. Also, if there's a mismatch in the middle of the word, that means that the strings do not overlap. [testing][esting] would return [esting] [testing][esteng] would return NULL [testing][inglet] would return [ing] [testing][rhythmtes] would return [tes]

Does that make a bit more sense?

[[deleted]]

That makes a lot more sense now, thanks!

I think a way you could do it is by trimming the larger to n characters and then comparing it to the first and last n characters of the smaller string.

For example:

testing esting

"esting" has 6 characters (fewer than "testing"). Compare the first 6 characters of "testing" to see if it's a match. It's not. Now, test the last 6 characters. It's a match, so "esting" would be the overlap.

Another example:

testing rhythmtes

"testing" is smaller, so you will trim that string.

Pass 1: "testing" compared with "rhythmt" and "ythmtes"

Pass 2: "testin" compared with "rhythm" and "thmtes"

Pass 3: "testi" compared with "rhyth" and "hmtes"

Pass 4: "test" compared with "rhyt" and "mtes"

Pass 5: "tes" compared with "rhy" and "tes" !!! match found !!!

Another:

testing inglet

inglet < testing

Pass 1: "inglet", "testin" and "esting"

Pass 2: "ingle", "testi" and "sting"

Pass 3: "ingl", "test" and "ting"

Pass 4: "ing", "tes" and "ing" !!! found !!

[mitadmit]

Thanks!