Use variable as placeholder in a path

I am trying to use a variable as a placeholder in a path but I keep getting an error.

data = dlmread(['/Users/reubs/Documents/Data/PO1/' cell2mat(filenames(trialnumber))],'',1,0);

I want to rewrite this as

path1 = '/Users/reubenaddison/Documents/Data/PO1/';
data = dlmread([fullfile(path1) cell2mat(filenames(trialnumber))],'',1;0);

but I get

"Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters."

Answer 1

[VBBV]

path1 = '/Users/reubenaddison/Documents/Data/PO1/';
data = dlmread(fullfile(path1, num2str(cell2mat(filenames(trialnumber)))),'',1,0);
%                               ^ convert num to str in fullfile             ^^ use a , in place of ;

Matlab recommends to use readmatrix than using dlmread. Read dlmread

Answer 2

[Image Analyst]

Try this:

folder = '/Users/reubenaddison/Documents/Data/PO1/';
fullFileName = fullfile(folder, filenames{trialnumber}) % Use braces!
data = dlmread(fullFileName);

See the FAQ to learn when to use parentheses, braces, and brackets:

https://matlab.fandom.com/wiki/FAQ#What_is_a_cell_array?