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search pattern without using built -in function

Asked by Elysi Cochin on 5 Apr 2013

how to search pattern without using regexp or strcmp function.... that is if i have a word "mississippi" the string "issi" "ssi" "ss"..... occurs two times.... how to write it in code without using built-in function..... how to search whether a particular pattern is in the word and its occurance without using built-in function...... please do reply.....

  1 Comment

What have you tried so far?



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2 Answers

Answer by Sean de Wolski
on 5 Apr 2013
 Accepted answer

doc regexp

  1 Comment

sir but regexp is a built-in function..... is it possible to do without any built-in function?? please do reply.....

Answer by Jan Simon
on 5 Apr 2013

Sorry, without built-in functions you cannot perform any useful operations in Matlab. Even the assignment using the "=" operator is a built-in function.

See Answers: What can be programmed without built-in functions


sir neednt look to my code.... i know its wrong.... please can you post the correct coding sir??.... please do reply....

The way you are using REGEXP makes it return an array of starting positions of the pattern in the array of characters that you are passing as a first argument.

You seem to have defined BWM as a rectangular array of characters, why? As Jan mention, should we understand that you have to find vertical occurrences or should we read BWM horizontally as if it were one long string? If such case, you could redefine it as

 BWM = BWM(:).' ;

in order to make it easier for us to understand that it is just one long string and to simplify further processing

Now let's admit that it is just one long string, could you exploit a FOR loop like the following for searching the pattern?

 for k = 1 : length(BWM)-length(expression)+1
    % do something

If you have to "highlight" matches by framing them with stars, you could for example build a second BWM while you read the first, which would include the stars (might be easier than try to insert stars in the current version).

thank u all

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