Help with c++!! Urgent! (1 Viewer)

[MuffinMan]

I have no idea why this program hangs when i type a positive integer greater than 1

The idea of the code is to add all the numbers from 1 to the number the user has inputted except when num mod 3 == 0, num < 10 && num mod 2 == 0;
HELP!!!!


code:

#include <iostream>
using namespace std;

int main()
{	 
	int sum, endingInteger, startingInteger = 1;
	
	cout <<"Enter an integer" << endl;
	cin >> endingInteger;
	
	while (endingInteger < 1)
		{
		cout <<"Error! you have entered an invalid value" << endl;
		cin >> endingInteger;
		}
	
	while (endingInteger > startingInteger)
		{
		while (endingInteger >= 1)
	
		
		
		{
			while (startingInteger <= 10)
				{
					switch (startingInteger % 2)
					{
					case 0: sum == sum;
							startingInteger++;
							break;
					case 1: sum = sum + startingInteger;
							startingInteger++; 
					}
				
				}
			}	 
					
			
			while (startingInteger > 10)
				if (startingInteger % 3 != 0)
				{
				sum = sum + startingInteger;
				startingInteger++;
				}
				
			else
				{
				sum == sum;
				startingInteger ++;
				}
			}
		
		cout <<" START\t" <<"      END\t" << "SUM" << endl;
		cout << "     1\t" << " \t"  <<  endingInteger << " \t " << sum  <<  endl;
				
	return 0;
}

 

[MuffinMan]

Damn vbulletin wouldnt accept indentation
Heres it in .cpp
open with wordpad

 

[MuffinMan]

i did initialise them

int main()
{
int sum, endingInteger, startingInteger = 1;

 

[MuffinMan]

to add all numbers from 1 to the number inputted, except when num < 10 and num mod 2 == 0 and except when num mod 3 == 0

 

[AntiHyper]

Why don't you just use scanf("%i", &<var_name>);
That way the compiler would know definitely what type of variable would be used as the input. Rather than cin.

Other than that, a quick trace led me to believe that the while loop on line 19 would always be infinitely true ie. endingInteger>=1 at all times, maybe your cpu would be able to detect this infinite loop and close down the program.

 

[sunny]

to add all numbers from 1 to the number inputted, except when num < 10 and num mod 2 == 0 and except when num mod 3 == 0

read endnumber
validate endnumber, use scanf as suggested
sum = 0
for num from startnumber to endnumber
  if num < 10 or num mod 2 == 0 or num mod 3 == 0 then
    do nothing
  else
    sum += num
  end if
end for
print sum

This should do the job according to your description, not sure why you need these nested loops.

 

[MuffinMan]

haha i gave up on it already
damn computers, why doesnt it work like you want it to?

 

[Lazarus]

Just so you know, I think the problem was this line:

		while (endingInteger >= 1)

'endingInteger' never changes, so if it enters the loop, it's always going to be greater than or equal to 1.

You do have a 'break' statement at one point, but it's nested in yet another loop, so it will only break out of the inner loop and not the outer loop.

 

[Jameswilmot2000]

Instead of using the loops why don't you add it up using the sum of a series formula

3 + 7 + 11 + 15 + ··· + 99 has a1 = 3 and d = 4. To find n, use the explicit formula for an arithmetic sequence.

We solve 3 + (n – 1)·4 = 99 to get n = 25.

Sn = 25/2[2 X 3 + (25 -1) X 4] = 1275

 

[MuffinMan]

cause we had to use repetition