C program to find sum of odd numbers from 1 to n

Write a C program to find sum of all odd numbers from 1 to n using for loop. How to find sum of all odd numbers in a given range in C programming. Logic to find sum of odd numbers in a given range using loop in C programming.

Input upper limit: 10

Sum of odd numbers from 1-10: 25

Required knowledge

Basic C programming, Relational operators, For loop

Learn more – Program to check odd numbers.

Logic to find sum of odd numbers from 1 to n

Step by step descriptive logic to find sum of odd numbers between 1 to n.

1. Input upper limit to find sum of odd numbers from user. Store it in some variable say N.
2. Initialize other variable to store sum say sum = 0.
3. To find sum of odd numbers we must iterate through all odd numbers between 1 to n. Run a loop from 1 to N, increment 1 in each iteration. The loop structure must look similar to for(i=1; i<=N; i++).
4. Inside the loop add sum to the current value of i i.e. sum = sum + i.
5. Print the final value of sum.

Program to find sum of odd numbers from 1 to n

/**
 * C program to print the sum of all odd numbers from 1 to n
 */

#include <stdio.h>

int main()
{
    int i, n, sum=0;

    /* Input range to find sum of odd numbers */
    printf("Enter upper limit: ");
    scanf("%d", &n);

    /* Find the sum of all odd number */
    for(i=1; i<=n; i+=2)
    {
        sum += i;
    }

    printf("Sum of odd numbers = %d", sum);

    return 0;
}

Note: Do not confuse with the shorthand assignment operator sum += i. It is equivalent to sum = sum + i.

Program to find sum of odd numbers in given range

/**
 * C program to print the sum of all odd numbers in given range
 */

#include <stdio.h>

int main()
{
    int i, start, end, sum=0;

    /* Input range to find sum of odd numbers */
    printf("Enter lower limit: ");
    scanf("%d", &start);
    printf("Enter upper limit: ");
    scanf("%d", &end);

    /* If lower limit is even then make it odd */
    if(start % 2 == 0)
    {
        start++;
    }
    
    /* Iterate from start to end and find sum */
    for(i=start; i<=end; i+=2)
    {
        sum += i;
    }

    printf("Sum of odd numbers between %d to %d = %d", start, end, sum);

    return 0;
}

Enter lower limit: 4
Enter upper limit: 11
Sum of odd numbers between 4 to 11 = 32

Happy coding 😉