Array Parameter Changed Into Vector Parameter (Passed by Reference)

[syeare]

Hello, I am trying to convert a double array parameter into a vector. I don't have a very full understanding of vectors and I couldn't comprehend the documentation ( http://www.cplusplus.com/reference/vector/vector/ ). I *DID* reference this earlier post:

http://www.cplusplus.com/forum/beginner/21957/

but I am still unsure. So FROM the 2nd code block, I should change it TO something like this 1st code block?

double calcStdDev(vector<double> data, int size)

double calcStdDev(double data[], int size)
{
	int i;
	double sum = 0.0, avg, stdDev = 0.0;
 
	// calculate sum of data
	for (i = 0; i < size; ++i)
	{ sum += data[i]; } 
 
	// calculate average
	avg = sum / size;
 
	// calculate and return the standard deviation
	for (i = 0; i < size; ++i)
	{ stdDev+= pow(data[i] - avg, 2); }
 
	 return sqrt(stdDev/ size);
}

[dutch]

Vectors keep track of their size, so you don't need to pass that separately. And you should pass it as a const reference instead of as a copy.

double calcStdDev(const vector<double>& data)
{
    // calculate sum of data
    double sum = 0.0;
    for (size_t i = 0; i < data.size(); ++i)
        sum += data[i]; 

    // calculate average
    double avg = sum / data.size();
 
    // calculate and return the standard deviation
    double stdDev = 0.0;
    for (size_t i = 0; i < data.size(); ++i)
        stdDev += (data[i] - avg) * (data[i] - avg);
    return sqrt(stdDev / data.size());
}

Vectors also have begin() and end() iterators and therefore can be used in a range-based for loop:

    double sum{};
    for (auto d: data) sum += d; 

    double avg = sum / data.size();

    double stdDev{};
    for (auto d: data) stdDev += (d - avg) * (d - avg);