Program not behaving as expected.

[pabs8]

Hi guys,

I am working on an exercise whereby after reading in sequence of values, I need to print the total sum, the greatest and the smallest values. The code below seems to do the trick, although for the min value, it always churns out 0 for some reason. Am I missing anything?

  int main()
try
{
	vector<double> dist;

	double sum = 0;	
	double min = 0;	
	double max = 0;

	cout << "please enter a whitespace-separated sequence of doubles: " << flush;
	double val = 0;
	while (cin >> val) {	
		
		if (val <= 0) {
			if (dist.size() == 0) error("no distances");
			cout << "total distance " << sum << '\n';
			cout << " smallest distance " << min << '\n';
			cout << "greatest distance " << max << '\n';
			cout << "mean distance " << sum / dist.size() << '\n';
			
			return 0;	
		}
		dist.push_back(val);	

		sum += val;
		if (val<min) min = val;
		if (max<val) max = val;
	}
	if (dist.size() == 0) error("no distances");
	cout << "total distance " << sum << '\n';
	cout << " smallest distance " << min << '\n';
	cout << "greatest distance " << max << '\n';
	cout << "mean distance " << sum/dist.size() << '\n';
	
}
catch (runtime_error e) {	
	cout << e.what() << '\n';
	
}
catch (...) {	 
	cout << "exiting\n";
}

[Peter87]

The min variable is initialized to 0 so unless you input a negative value it will not get updated. You have the same problem with the max variable if the user only inputs negative numbers.

[pabs8]

Thanks, although I've had already thought about this issue; I need to initialize both variables with something though otherwise I get an error. My max variable gets updated anyway, but not min....

[Peter87]

A common technique in this kind of situation is to initialize the variable to a very large value, preferably the largest possible value that the type can hold. Floating point type usually has a special value for infinity that will compare greater than any finite value.

http://en.cppreference.com/w/cpp/types/numeric_limits/infinity

[pabs8]

Thanks Peter, I'll give that a try.

[pabs8]

Peter, You're a genius, it worked!! I used double inf = std::numeric_limits<double>::infinity();
Thanks for taking the time to have a look at my code.