MATLAB: How to determine if a function foo in file foo.m has an empty documentation string in r2017b (or later)

distance_learningdocumentation stringmatlab onlinematlab_onliner2017b

On previous versions, isempty(help('foo')) worked, but now it seems help('foo') returns a non-empty, non-constant default.

Best Answer

function tf = isemptyhelp(topic)
  %returns true if topic is not a function with a documentation string
  %including returning true for anything that is not a function or function handle
    %examples of first line of help output in R2017b:
    %  Input is a value of type double.
    %  f is a variable of type function_handle.
    %  f is a function.
    helpstr = help(topic);
    tokens = regexp(helpstr, '\s+', 'split');
    tf = isempty(tokens) || (length(tokens) >= 4 && strcmp(tokens{2}, 'is') && strcmp(tokens{3}, 'a');
  end

Related Solutions

MATLAB: How to call a C# function, foo(out byte [])? — help passing a byte pointer

Hi,

have you tried calling it like this

[bool_val, byte_array] = obj.GetLatestBuffer();

This works fine for me in 14a with the following example

            public bool GetLatestBuffer(out byte[] Buffer)
            {
                Buffer = new byte[10];
                for (int i = 0; i < 10;i++)
                {
                    Buffer[i] = (byte)i;
                }
                return true;
            }

ML:

>> a = ClassLibrary1.Class1
a = 
Class1 with no properties.
>> [bool,array] = a.GetLatestBuffer()
bool =
       1
array = 
Byte[] with properties:
            Length: 10
        LongLength: 10
              Rank: 1
          SyncRoot: [1x1 System.Byte[]]
        IsReadOnly: 0
       IsFixedSize: 1
    IsSynchronized: 0

SideNote: The out keyword forces the routine GetLatestBuffer to assign Buffer to some value. So you do NOT need to pass down a preallocated array and since you dont need to do this it appears as output in MATLAB directly.

Also in C# when using OUT you never pass down a preallocated array. So what MATLAB does is correct here and matches the .NET programming.

MATLAB: Hello. I have to write a function called occurrence that tests whether a character exists in a string. If it is present, display true and the position (index) of the character. If it is not present, return inf. it gives me an error in line 2. help?

function find_letter(L, string)
    n= length(L);
    not_found = true; 
       for k = 1:n
          if isequal(L(k), string)
             fprintf('letter %s is present! It is the %2.0d item\n', L(k), k);
             not_found = false; 
             break; % or return 
          end
       end 
     if not_found; fprintf('letter not present\n')
     end
    find_letter('Hello World!','o');

Best Answer

Related Solutions

MATLAB: How to call a C# function, foo(out byte [])? — help passing a byte pointer

MATLAB: Hello. I have to write a function called occurrence that tests whether a character exists in a string. If it is present, display true and the position (index) of the character. If it is not present, return inf. it gives me an error in line 2. help?

Related Question