Compare 2 strings without using ismember or strcmp

Hi, I've got a code that gives me different outputs and I want to compare the messages inside them and the ones that are not in one string(X) and are in the other(Y) write them into another output. Lets see:

K is the number of messages that has an string.

If K from X is not in Y = L

And I do not want to use ismember or srcmp because the proces would be very long.

I guess I have explained myself.

Thank youuu for the answer!!!

[Stephen23]

@vicente Noguer: please give actual examples of X and Y that we can use, and the expected output.

[DGM]

It's not really clear what your variables are or how they are arranged. This is how I read the problem statement:

"[I have] [two?] outputs and I want to compare the messages inside them ... [and I want to extract the ones that are unique to Y]"

Are these actual string arrays, or are they cell arrays of character vectors? Are they something else? Are there actually only two?

What about them would make the built-in tools exceptionally slow?

In some certain restricted cases, there are some faster alternatives to ismember(), but I don't know if any of that even applies, because I don't know what your variables are.

[flashpode]

a = [qwert34776;
    dnfien/8863;
    feihfidi234;
    939405'cncieni;
    300oppdf;
    din2004ms;]
b = [qpwn3feini;
    300oppdf;;
    hfgt4568;
    qwert34776;
    dnfien/8863]

This could be an example of imputs and the output woulf be the ones that are in a that they are not in b.

And using ismember or strcmp slows the proces because the inputs I got have a lot of data to be comparing one by one

[flashpode]

I made an example of two imputs if you want the original inputs I can give you but they are this way mixing some letters with numbers and comas, etc

Answer 1

[Stephen23]

Presuming that your examples with invalid syntax are actually supposed to be string arrays:

a = ["qwert34776";"dnfien/8863";"feihfidi234";"939405'cncieni";"300oppdf";"din2004ms"];
b = ["qpwn3feini";"300oppdf";"hfgt4568";"qwert34776";"dnfien/8863"];
c = setdiff(a,b)

c = 3×1 string array
    "939405'cncieni"
    "din2004ms"
    "feihfidi234"

Most likely using SETDIFF will be faster than writing your own function (including time to write, time to test, time to debug, time to maintain, and runtime).

[flashpode]

Yeah that really help!! Thank you!!