Finding a character in a string?
조회 수: 77 (최근 30일)
이전 댓글 표시
so I have the following line of code:
hashtag=lower(input('Which hashtag would you like information on?','s'));
This prompts the user to input a hashtag, like say '#helloworld'. However, the program runs even without the user putting the hashtag. So it runs even if they only input "helloworld", which presents problems for me later on. How can I get the code to stop reading and present an error message if there is no hashtag symbol in the user's input? Apparently the # character means something in matlab as well which is causing me problems.
I have this so far but it seems not to work:
if k=(strfind(hashtag,'#')))
error('Please include the hashtag')
end
댓글 수: 0
채택된 답변
The Matlab Spot
2013년 12월 3일
using start anchor with regexp will ensure that you '#' as the first character of you input string.
hashtag=lower(input('Which hashtag would you like information on?','s'));
if(isempty(regexp(hashtag,'^#','once')))
error('Please include the hashtag')
end
댓글 수: 2
Jos (10584)
2013년 12월 3일
using regexp for this problem is like killing a mosquito with a nuclear missile ...
추가 답변 (2개)
sixwwwwww
2013년 12월 3일
Dear Johny, try this:
hashtag=lower(input('Which hashtag would you like information on?','s'));
if isempty(strfind(hashtag, '#'))
error('Please include the hashtag')
end
댓글 수: 0
Jos (10584)
2013년 12월 3일
Per definition a hashtag starts with a # sign followed by one or more letters or numbers
So, quite simply, check all these three requirements:
str = lower(input('Which hashtag would you like information on?','s'));
if numel(str)<2 || str(1) ~= '#' || ~all(ismember(str(2:end),['a':z' '_' '0':'9']))
error('Input is not a valid hashtag') ;
end
댓글 수: 0
참고 항목
카테고리
Help Center 및 File Exchange에서 Characters and Strings에 대해 자세히 알아보기
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!