Arrays and Vectors

[acronym]

I'm keep on getting an error saying there's an unresolved external. What I have to do for the program is take a certain amount of values and take the difference of the sum of the values and the minimum value. Can someone please help?

#include <iostream>
#include <vector>

using namespace std;

vector<double> read_inputs()
{
	vector<double> result;
	cout << "Please enter values, Q to quit: " << endl;
	bool more = true;
	while (more)
	{
		double input;
		cin >> input;
		if (cin.fail())
		{
			more = false;
		}
		else 
		{
			result.push_back(input);
		}
	}
	return result;
}

double minimum(vector<double> data)
{
	double smallest = data[0];
	for (int i=1; i < data.size(); i++)
	{
		if (data[i] < smallest)
		{
			smallest = data[i];
		}
	}
	return smallest;
}
double sum(vector<double> data)
{
	for(int i=0; i < size; i++)
	{
		total= total + data[i];
	}
	return total;
}

int main()
{
	vector<double> scores= read_inputs();
	if (scores.size() == 0)
	{
		cout<< "At least one score is required. " << endl;
	}
	else
	{
		double total = sum(scores-minimum);
		cout <<  "Final score: " << total << endl;
	}
	return 0;
}

[hamsterman]

gcc error messages:

prog.cpp: In function ‘double sum(std::vector<double, std::allocator<double> >)’:
prog.cpp:41: error: ‘size’ was not declared in this scope

This should be data.size()

prog.cpp:43: error: ‘total’ was not declared in this scope
prog.cpp:45: error: ‘total’ was not declared in this scope

You need to add "int total;" at the beginning of sum().

prog.cpp: In function ‘int main()’:
prog.cpp:57: error: no match for ‘operator-’ in ‘scores - minimum’

scores is a vector, minimum is a function. How do you expect to subtract one from another?