MATLAB: If the file is not found or the character is not a valid char, the function should return a value -1.

MATLAB

I am creating a function that counts the given character present in the text file. Problem I am facing is if the text file is not found the function should return value -1 and also if the given character is not a valid one it should return -1.
function [charnum]=char_counter(fname,character)
fid=fopen(fname,'rt')
if fid<0 || ischar(character)==0
    charnum=-1;
else
str=fileread(fname);
if strncmpi(character,str,inf)==0
    charnum=-1;
end
charnum=count(str,character);
end

Best Answer

How are you defining a valid character? You can use try,catch.
function [charnum]=char_counter(fname,character)
try fid=fopen(fname,'rt'); 
catch 
    charnum=-1;
    return;
end
if fid<0 || ischar(character)==0
    charnum=-1;
else
str=fileread(fname);
if strncmpi(character,str,inf)==0
    charnum=-1;
end
charnum=count(str,character);
end
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