How do I detect a "tab" character in a line of text read by fgetl?

I am using fgetl to read lines in a text file. Is there a way to detect whether one of the whitespace characters is a "tab" ?

Thanks in advance for your help.

Answer 1

[dpb]

l=fgetl(fid);
istab=(l==9);                    % the fast way...
% 
istab=strfind(l,char(9));        % the char() string string functions way

[Clay Fulcher]

Thanks!! Greatly appreciated.

Answer 2

[Walter Roberson]

S = sprintf('abc\tdef');     %text with a tab in it

S == 9                       %fast, simple, and tab character unlikely to change any year soon

strfind(S, sprintf('\t'))    %just in case tab someday changes to a multi-character sequence

%unicode defines three additional tab-related functions
ismember(S, [0x09 0x0b 0x88 0x89 0x8a])   %HT VT CTS CTJ LTS

%unicode defines several tab symbols
ismemember(S, [0x09 0x0b 0x88 0x89 0x8a 0x2409 0x240b 0x21b9 0x21c6 0x21E4 0x21E5])   %HT VT CTS CTJ LTS various tab symbols

[Clay Fulcher]

Thanks Walter! Great help.

Answer 3

[Clay Fulcher]

Thanks to Walter Roberson and dpb for the help above. Here is the new "tab detector!"

function [x, tabpositions] = istab(line)

%

% This function detects any "tab" characters in a character string and

% returns logical TRUE if tabs are present, or logical FALSE if tabs are

% not present. Optionally returns the positions of the tab(s) in the line.

%

% USAGE

% [x,tabpositions]=istab(line)

%

% INPUT

% line - [1 x n] character string with or without tabs

%

% OUTPUT

% x - logical TRUE or FALSE indicating presence of tab(s) in line.

% tabpositions - [1 x ntabs] vector showing positions of tabs in line.

%

% line must be a character string or empty

if ~ischar(line) & ~isempty(line)

disp(' ')

disp(' Input must be a character string.')

return

end

% line must contain only one line

if size(line,1)>1

disp(' ')

error(' Character string must be no more than one line.' )

return

end

% Put logical 1 where tab exists, logical 0 where it does not in string.

% Could use x=(line==9), but the following eliminates the case where this

% designator for the tab character is changed in the future.

x=(line==sprintf('\t'));

% Find the positions in line where tabs exist.

tabpositions=find(x);

if isempty(tabpositions), tabpositions=[]; end

% Return only logical 1 or 0, however many tabs there are in line.

x=x(find(x));

if ~isempty(x), x=x(1); end

if isempty(x), x=logical(0); end

% Display the logical result for tab existence.

if x, 1==1, end

if ~x, 1==2, end

return