Odd numbers using a for loop help

[Crcullen3916]

Hi, I have this assignment that I have almost finished except I have one problem. I'm having trouble making my for loop find the sum of the first n odd numbers ( n being the variable in which a value is read in)
oddnum and oddsum are the variables i came up with
This is what I have so far :

int sumodd (int n)
{
    int oddnum, oddsum = 0;
 
    for (oddnum = 1; oddnum <= n; oddnum++)
        oddsum += oddnum * oddnum;
    return oddsum;
}

Can anyone help me fix this??? My professor says it's right and that I just have to fix the limit. I don't know what she means. I asked this other guy for help and he came up with this:

int sumodd (int n)
{
    int oddnum, oddsum = 0;
 
    for ( oddnum = 0; oddnum < n; oddnum++)
        if( (oddnum % 2) != 0 )
            oddsum += oddnum;
 
    return oddsum;
}

But that doesn't work either!

[Ganon11]

The second method you have should be working - what input are you using, and what output are you getting?

[lqdeffx]

Typically, in a situation like this, I would create a quick print function that allows me to iterate through the loop and see how the values are changed. You might be having a problem elsewhere in the code!

[Crcullen3916]

The second method you have should be working - what input are you using, and what output are you getting?

This is my output:

Cassandra Cullen                Assignment 3
 
Enter a value, 0 to stop > 1
 
the sum of the first 1 cubes is 1
the check is 1  CORRECT
 
the sum of the first 1 odd numbers is 0
the check is incorrect
 
Enter a value, 0 to stop > 2
the sum of the first 2 cubes is 9
the check is 9  CORRECT
 
the sum of the first 2 odd numbers is 1
the check is incorrect
 
Enter a value, 0 to stop > 3
the sum of the first 3 cubes is 36
the check is 36 CORRECT
 
the sum of the first 3 odd numbers is 1
the check is incorrect
 
Enter a value, 0 to stop > 4
the sum of the first 4 cubes is 100
the check is 100        CORRECT
 
the sum of the first 4 odd numbers is 4
the check is incorrect
 
Enter a value, 0 to stop > 5
the sum of the first 5 cubes is 225
the check is 225        CORRECT
 
the sum of the first 5 odd numbers is 4
the check is incorrect
 
Enter a value, 0 to stop >

I'll put the whole program up because maybe it's something else:

// reads in a series of numbers to be stored in the variable n
// sumcubes function finds the sum of first n cubes
// sumodd function finds the sum of the first n odd numbers
// labelit function prints a heading on the output with name and program number
#include <iostream>
using namespace std;
void labelit (void);
int sumcubes (int n);
int sumodd (int n);
int main () {
    int n, valuecube, valueodd, check1, check2;
 
    labelit ();
    cout << "Enter a value, 0 to stop > ";
    cin >> n;
    cout << endl;
    while (n!= 0) {
          valuecube = sumcubes(n); 
 
          cout << "the sum of the first " << n << " cubes is " << valuecube
                   << endl;
 
          check1 = (n * (n + 1) / 2) * (n * (n +1) /2);
 
          if (check1 == valuecube)
             cout << "the check is " << check1 << "\t" << "CORRECT" << endl 
                      << endl;
          else
              cout << "the check is incorrect" << endl << endl;
 
          valueodd = sumodd (n);
 
          cout << "the sum of the first " << n << " odd numbers is " 
                   << valueodd << endl;
 
          check2 = n * n;
          if (check2 == valueodd)
             cout << "the check is " << valueodd << "\t" << "CORRECT" 
                      << endl << endl;
          else
              cout << "the check is incorrect" << endl << endl;
          cout << "Enter a value, 0 to stop > ";
          cin >> n;
    }
    system ("pause");
    return 0;
}
 
void labelit (void) 
{
     cout << "Cassandra Cullen " << "\t\t" << "Assignment 3" << endl 
              << endl;
}
 
int sumcubes (int n)
{
    int item, sum = 0;
 
    for (item = 1; item <= n; item++)
        sum += item * item * item;
    return sum;
}
 
int sumodd (int n)
{
    int oddnum, oddsum = 0;
 
    for ( oddnum = 0; oddnum < n; oddnum++)
        if( (oddnum % 2) != 0 )
            oddsum += oddnum;
 
    return oddsum;
}
 
 

[Ganon11]

Your sumodd loops from 0 to n - 1 - change the header to

for (oddnum = 0; oddnum <= n; oddnum++)

to count the last value of n.

[soumya2home]

#include<stdio.h>
#include<conio.h>
main()
{
int a,n;
printf("\nEnter the no : ");
scanf("%d",&n);
for(a=1;a<=n;a++)
if(a%2!=0)
printf("\n%d",a);
getch();
}

[green381]

it looks funky in variables but it works .i have tried it .
i an a learner if it is wrong sorry for the time u wasted .

#include<stdio.h>
#include<math.h>
main()
{
int n,b,c,totalsum;
printf("Entre the value of n");
scanf("%d",&n);
for (b=1;b<n;b++)
c=n/2;
totalsum=c*c;
printf("The sum of odd numbers up to %d is %d",n,totalsum);
getch();
}