Thread: What's wrong with this program, and how to fix it?

Hi,

When I compile this program, there's always a message on the screen as below:

"exer3.cpp: In function ‘int main()’:
exer3.cpp:13: warning: comparison between signed and unsigned integer expressions
exer3.cpp:18: warning: comparison between signed and unsigned integer expressions
exer3.cpp:22: warning: comparison between signed and unsigned integer expressions
exer3.cpp:27: warning: comparison between signed and unsigned integer expressions
exer3.cpp:35: warning: comparison between si "

Despite this, I am able to run the program and have the expected results. However, I don't know how to fix the areas of the program which the warnings point to. Could you please help? Thanks a lot!

Code:

// Exercise 3/Chapter 3: Programming: Principles and Practice using C++

#include "std_lib_facilities.h"

int main()
{
	vector <double> myvector;
	double number = 0;
	while (cin >> number)
		myvector.push_back(number);
	
	double sum = 0;
	int i;
	for (i = 0; i < myvector.size(); ++i)
		sum += myvector[i];
	
	// compute distance
	vector <double> mydistance;
	for (i = 0; i < (myvector.size()-1); ++i)
		mydistance.push_back(myvector[i+1]- myvector[i]);
	
	cout << "Numbers: " << endl;
	for (i = 0; i < myvector.size()-1; ++i) {
		cout << " " << myvector[i];
	}
	
	cout << "\nDistance: " << endl;
	for (i = 0; i < mydistance.size(); ++i) {
		cout <<" " << mydistance[i];	
	}
	
	// find min, max
	double max, min;
	max = min = myvector[0];
	cout << '\n';
	for (i = 0; i < myvector.size(); ++i) {
		if (myvector[i] > max) {
			max = myvector[i];
			cout << "Max = " << max << "\tMin = " << min << endl;
			min = max;
		}
		else if (myvector[i] < max) {
			min = myvector[i];
			cout << "Max = " << max << "\tMin = " << min << endl;
			max = min;
		}
		
	}
	
}