I need to take a string ,and return the first recurring character.

n this homework you must take a string and return the first recurring character in that string. For example if you are given ‘ABCA’ as the input then there is only one recurring character and your programming code should return ‘A’. If you are given ‘ABCBA’ then there is two recurring character ‘A’ and ‘B’ but the first recurring character is ‘B’ thus your code should return ‘B’. If you are given ‘ABC’ then there is no recurring character and your code returns ‘there is no recurring character’. You must use only commands and functions that we learned in this class during the semester.

[Dyuman Joshi]

"homework"

What have you tried yet? If you have not written a code, then a logic on how to proceed.

"You must use only commands and functions that we learned in this class during the semester."

How are we supposed to know this?

[Stephen23]

Original question by Jose Hernandez retrieved from Google Cache:

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https://web.archive.org/web/20211201190444/https://www.mathworks.com/matlabcentral/answers/1598894-i-need-to-take-a-string-and-return-the-first-recurring-character

I need to take a string ,and return the first recurring character.

n this homework you must take a string and return the first recurring character in that string. For example if you are given ‘ABCA’ as the input then there is only one recurring character and your programming code should return ‘A’. If you are given ‘ABCBA’ then there is two recurring character ‘A’ and ‘B’ but the first recurring character is ‘B’ thus your code should return ‘B’. If you are given ‘ABC’ then there is no recurring character and your code returns ‘there is no recurring character’. You must use only commands and functions that we learned in this class during the semester.

[Rena Berman]

(Answers Dev) Restored edit

Answer 1

[Murali Manikanti]

Assuming that only A-Z characters are allowed in the input string. Scan the String from left to right and set the flag to ‘true’ for each character visited. (say visited(‘A’) = ‘true’). At any index, if visited(‘char’) is already ‘true’ then return that character.

You can make use of loops and arrays in MATLAB to convert the above logic to code.

Answer 2

[Tyler F]

Without helping you too much for a HW assignment, there are a few other commands you can use that may be included in your approved command list. As Murali said you can loop over and keep a register of which characters you have visited. You could also use a loop and the any() command to check if any of the next characters are equal to the current character without having a predefined list of characters (e.g. word = 'ABCDEBF'; any(word(3:end) == word(2));.

You could also use the unique command to quickly tell if there were no repeated characters (ill let you read the documentation on your own for this one)