What do these lines of code mean

I am working on a homework assignment where I have to code a linear search algorithm, and looked up a video to see other solutions. I am confused what the code on lines 2 and 6 mean practically. Is it first initializing an empty array than storing the found user value into that array?

See code below:

1) x = input('Enter the array:');

2) Y = [];

3) y = input('Enter the number you want to seach:');

4) for i=1:length(x)

5) if (x(i)==y)

6) Y = [Y i];

7) end

8) end

Answer 1

[Walter Roberson]

Yes. That code starts with an empty output, and then each time it finds a match, it appends the index of the match at the end of the list.

[Camden Nelson]

Ah I see. Thank you!

Answer 2

[Voss]

"Is it first initializing an empty array"

Yes.

"[then] storing the found user value into that array?"

Storing the index (i) at which the user's value was found. Specifically, line 6 is storing all the indices at which the user's value was found, and doing so by concatenating them one-by-one with the array Y, and storing the result as the new Y each time.

Consider the following code. Each time, Y = [Y i]; appends a new value to the end of Y by concatenating the existing Y with the new value i.

Y = [];

i = 2;
Y = [Y i]

Y = 2

i = 5;
Y = [Y i]

Y = 1×2

2 5

i = 10;
Y = [Y i]

Y = 1×3

2 5 10

[Camden Nelson]

Okay gotcha. That makes a lot more sense seeing it step by step. Thanks!

[Steven Lord]

FYI for future reference, you can step through code line by line using the debugging tools if that helps you more easily understand what the code is doing.