Question

I need to write a function whose input argument should be file name, and the function will perform certain operation on the opened file. Here is the sample function I wrote,

 function readFile = loadOneColumnFile(fileName)
 fid1 = fopen(fileName);
 readFile = 0;
 fclose(fid1);

But when I invoke this function in the command console as follows,

>> testValue = loadOneColumnCSV('/usr1/test.csv');

The Matlab returns the following error message

??? Undefined function or method ‘loadOneColumnFile’ for input arguments of type ‘char’.

Looks like that the definition of function is not correct. How to fix it? Thanks.

Answer 1

MATLAB treats a string as an array of characters (like C++, except the strings are not null-terminated in MATLAB).

Despite the error message, I don’t think there is any problem with the string passing. The problem is MATLAB cannot find your function. So:

1. The file containing the function must have same name as the function (in your case save the function in a file named loadOneColumnFile.m)
2. The loadOneColumnFile.m must be placed in the working (current) directory so MATLAB could find it.
3. The name of the function is not consistent in your question. Make sure you have used only one of the loadOneColumnFile or loadOneColumnCSV for naming the function and filename.