Sum of numbers problem..

[JoeyX64]

I got the last part correct and part of the beginning too but i can't get it completely correctly. The question asks "Write a program that asks the user for a positive integer value. The program should use a loop to get the sum of all the integers from 1 up to the number entered. For example, if the user enters 50, the loop will find the sum of 1,2,3,4.......50. input validation: Do not accept and input that is less than 1."

This is what I have so far, I've been trying to get it right on my own but i can't figure it out.

#include <iostream>
using namespace std;
int main ()
{
	int sum = 0, input;
	
	cout << "Enter any positive integer.\n";
	cin >> input;

	for (int num = 1; sum += num; num++)
		
		if (input > 1)
		{
			sum += num;
			num++;
		
			cout << "The sum of numbers 1 - " << input 
			<< " " << "is " << sum << endl;
			break;
		}
		
		else
		{
			cout << "\n" << input << " is negative number.";
			cout << " The program will now terminate.\n";
			break;
		}
	
	return 0;
	}

[Stewbond]

It's the middle argument in the for loop:

#include <iostream>
using namespace std;
int main ()
{
	int sum = 0, input;
	
	cout << "Enter any positive integer.\n";
	cin >> input;

	for (int num = 1; num <= input; num++)
		
		if (input > 1)
		{
			sum += num;
			num++;
		
			cout << "The sum of numbers 1 - " << input 
			<< " " << "is " << sum << endl;
			break;
		}
		
		else
		{
			cout << "\n" << input << " is negative number.";
			cout << " The program will now terminate.\n";
			break;
		}
	
	return 0;
	}

[JoeyX64]

I figured out the problem, but now i can't figure out how to validate input. Any help will be much appreciated.

#include <iostream>
using namespace std;
int main ()
{
	int sum = 0;
	int num;

	
	cout << "Enter a number greater than 0.\n";
		cin >> num;

		
	for (int counter = 0; counter <= num; counter++)
	
	{	
		sum = sum + num;
		
		counter++;
	}
	
	cout << "The sum of numbers 1 - " << num
			 << " " << "is " << sum << endl;
		
	if (num < 1) //Here is where i am messing up. (I think)
		{
			cout << "\n" << num << " is an invalid input.";
			cout << " The program will now terminate.\n";
		
		}
	
	return 0;
	}

[JoeyX64]

Nevermind somehow i made it work... Was there an easier way to do this?

#include <iostream>
using namespace std;
int main ()
{
	int sum = 0;
	int num;

	
	cout << "Enter a number greater than 0.\n";
		cin >> num;
	
		
	for (int counter = 0; counter <= num; counter++)
	
	{	
		
		sum = sum + num;
		
		counter++;
	}
	

	if (num < 1)
		
	{
			cout << "\n" << num << " is an invalid input.";
			cout << " The program will now terminate.\n";
		
	}
	
	else

	
	cout << "\nThe sum of numbers 1 - " << num
			 << " " << "is " << sum << endl;
		
	
	return 0;
	}