Calculator (with functions)

function s = nsum(a,b)
    %MatLab have a function called sum
    s = str2num(cell2mat(a))+str2num(cell2mat(b));
end

function s = sub(a,b)
    s = str2num(cell2mat(a))-str2num(cell2mat(b));
end

function m = multi(a,b)
    m = str2num(cell2mat(a))*str2num(cell2mat(b));
end
function d = div(a,b)
    d = str2num(cell2mat(a))/str2num(cell2mat(b));
end

calc = input('Insert some values and the type of calculation (Ex: 53+35): ','s');
not_digit = isstrprop(calc,'digit');

for e = 1:1:length(calc)
    if not_digit(1,e) == 0
        numbers = strsplit(calc, calc(1,e));
        result = 0;
        switch calc(1,e)
            case '+'
                result = nsum(numbers(1,1),numbers(1,2));
            case '-'
                result = sub(numbers(1,1),numbers(1,2));
            case '*'
                result = multi(numbers(1,1),numbers(1,2));
            case '/'
                result = div(numbers(1,1),numbers(1,2));
        end
        fprintf('The result of %s = %d\n',calc,result)
    end
end