Issues during conversion into C++

Hi everyone,

I'm having troublesome time during the conversion of this function into C++ - readable code

function [b,a] = ComputeButterworthCoeffs(fs, order, type, fc, flow, fupp)

fn = fs/2;

oc = fc/fn;
olow = flow/fn;
oupp = fupp/fn;

if strcmp(type,'bandpass') || strcmp(type,'stop')
    
    if olow>1 || oupp>1
        error('Upper and lower frequencies must be BOTH lower than Nyquist frequency')
    end
    
    [b,a] = butter(order, [olow oupp], type);
else
    if oc>1
    error('Cut frequency must be lower than Nyquist frequency')
    end

    [b,a] = butter(order, oc, type); 
end
end

These are the errors I get, they all refer to the 'butter' function call:

What am I doing wrong?

Is there some link dealing with the same issue?

Thanks in advance.