fopen() in R2008 does not use variables?

I am trying to open a series of text files and I am getting the 'Invalid filename' error. This is the code:

[FName,PathName,FilterIndex] = uigetfile('C:\temp\matlab\data','MultiSelect','on');

% read in input file
% the input data is one col of floats in text
for f = 1:length(FName)
    filename = strcat('C:\temp\matlab\data\', FName(f))
    fid = fopen(filename,'rt');
    data = fscanf(fid, '%f', 90000 );
    fclose(fid);
....

This is what I get for filename:

filename = 

    'C:\temp\matlab\data\sample0.txt'

I did some debugging and I can open the files one by one if I put the string literal as the first argument to fopen().

Questions:

Does this function only take string literals in R2008?

If so, is there a workaround?

Using MATLAB Version 7.6.0.324 (R2008a)

Thanks,

Ed

Answer 1

[Steven Lord]

The FName output in your uigetfile call is a cell array. When you use parentheses to index into a cell array the result is also a cell array. Calling strcat on a cell array and a char array results in a cell array. fopen does not accept a cell array as its first input.

Instead use curly braces to extract the contents of the cell in FName, which will be a char array. Calling strcat on a char array and a char array results in a char array that fopen can accept.

sample = {'abc'; 'def'; 'ghi'}
xCell = sample(1)
xChar = sample{1}
yCell = strcat(xCell, '123')
yChar = strcat(xChar, '123')

whos

Answer 2

[Roshan Chavan]

FName(f) is a cell. Convert it to a character array by using char(Fname(f)).

[FName,PathName,FilterIndex] = uigetfile('C:\temp\matlab\data\','MultiSelect','on');
% read in input file
% the input data is one col of floats in text
for f = 1:length(FName)
    fid = fopen(strcat(PathName,char(FName(f))),'rt');
    data = fscanf(fid, '%f', 90000 );
    fclose(fid);
....

Answer 3

[Ed Seger]

Thanks for the responses, these solved the problem. This focuses on a complaint that I have had about matlab documentation for years, they dont show the type of the arguments in the built-in functions in the help.

Ed