You need to use "strrep" function which will replace newline character (newline) in the captured text with HTML line break tags (<br>), preserving the line breaks in the web display. After that while concatenating the string use the <pre> tag which will preserves both spaces and line breaks. Please refer to the following code:
% Evaluate and capture the contents of 'readbmp'
test = evalc('type readbmp');
% Replace newline characters with HTML line breaks
test_html = strrep(test, newline, '<br>');
% Concatenate the HTML formatted string
str = strcat('text://<html><body><pre>', test_html, '</pre></body></html>');
% Open the formatted string in a web browser
web(str);
For more information regarding the "strrep" function, kindly refer to the below MATLAB documentation:
