➤ If-else Statement in C
➤ Programs on if-else
➤ Switch Case in C
➤ Switch case Programs
➤ Conditional Operator
➤ While loop in C
➤ Do-while loop in C
➤ While vs do-while
➤ For loop in C
➤ Break keyword in C
➤ Continue keyword in C
➤ Break vs Exit in C
➤ Goto keyword in C
☕️ Flow Control Programs
➤ Largest in 3 Numbers
➤ Find Grade of student
➤ Find the absolute value
➤ Vowel or Consonant
➤ Leap Year Program
➤ Simple calculator in C
➤ Check Odd or Even
➤ Roots of Quadratic Equation
➤ Find Reverse of Number
➤ Factors of a number in C
➤ Generate Multiplication table
➤ Find Power of a Number
➤ Find GCD and LCM
➤ Find factorial of Number
➤ Count Number of Digits
➤ Sum of digits in Number
➤ Sum of N Natural Numbers
➤ Sum of Squares of Natural No.
➤ Find Sum of Odd Numbers
➤ Find the Sum of Series
➤ Find Fibonacci series in C
➤ Sum of the Fibonacci series
➤ Sum until enters +ve numbers
➤ Sum of max 10 no. & Skip -ve
☕️ C Conversion Programs
➤ Celsius to Fahrenheit
➤ Fahrenheit to Celsius
➤ Decimal ↔ Binary
➤ Decimal ↔ Octal
➤ Octal ↔ Binary in C
☕️ Number Programs in C
➤ Prime Number in C
➤ Strong Number in C
➤ Krishnamurthy Number
➤ Neon Number in C
➤ Palindrome number
➤ Perfect Number in C
➤ Armstrong Number
☕️ Pattern Programs in C
➤ Pattern programs in C
➤ Printing pattern using loops
➤ Floyd’s triangle Program
➤ Pascal Triangle Program
➤ Pyramid Star Pattern in C
➤ Diamond Pattern Programs
➤ Half Diamond pattern in C
➤ Print Diamond Pattern
➤ Hollow Diamond Pattern
➤ Diamond Pattern of Numbers
To find the sum of odd numbers in C, first, we need to check number is odd or not.
There are many different ways to check the number is odd or not, for example:- using modulus operator (%), using division and multiplication operator, and using a bitwise operator.
Initialize a variable sum
with value 0. If the number is odd then add it with the variable sum.
Sum of First Odd Numbers in C from 1 to N
To solve this problem loop can be used. Below the program find the sum of odd numbers from 1 to N numbers using for loop.
#include<stdio.h>
int main()
{
int n, sum=0;
printf("Enter n value: ");
scanf("%d",&n);
for(int i=1; i<=n; i++)
{
if(i%2!=0) sum += i;
}
printf("Sum of odd numbers from 1 to %d is: %d", n, sum);
return 0;
}
Output for the different test-cases:-
Enter n value: 10
Sum of odd numbers from 1 to 10 is: 25
Enter n value: 20
Sum of odd numbers from 1 to 20 is: 100
In this program, we first check number is odd or not. There is a more simple way to find the sum of odd numbers from 1 to N.
The first odd number is 1, then the next odd number is 3, i.e (1+2). So, update expression should be i=i+2 for the initialization variable i. It will decrease the times of iteration of the for a loop.
#include<stdio.h>
int main()
{
nt n, sum=0;
printf("Enter n value: ");
scanf("%d",&n);
for(int i=1; i<=n; i=i+2)
{
sum += i;
}
printf("Sum of odd numbers from 1 to %d is: %d\n", n, sum);
return 0;
}
Output for different test-cases:-
Enter n value: 10
Sum of odd numbers from 1 to 10 is: 25
Sum of first N odd numbers without using a loop
We can also find the sum of odd numbers in C without using a loop. For this purpose, we need to use an odd number theorem.
Sum of first N odd numbers = N*N
The sum of the first N odd numbers is equal to the square of the number N.
For example, the first 5 odd numbers are:- 1, 3, 5, 7, and 9
Their sum is 1+3+5+7+9 = 25 we know that 25 is the square of the number 5.
Similarly,
The sum of the first 10 odd numbers is:-
1+3+5+7+9+11+13+15+17+19 = 100, and the 100 is the square of the number 10.
#include<stdio.h>
int main()
{
int n, sum;
printf("Enter n value: ");
scanf("%d",&n);
sum = n*n;
printf("The sum of first %d odd numbers is: %d\n", n, sum);
return 0;
}
Output for the different test-cases:-
Enter n value: 10
The sum of the first 10 odd numbers is: 100
Enter n value: 20
The sum of the first 20 odd numbers is: 400
Sum of odd numbers within a range
Sometimes we need to find the sum of odd numbers within a range i.e. from m to n. It is similar to the previous programs.
#include<stdio.h>
int main()
{
int minRange, maxRange, sum=0;
printf("Enter min and max value of the range: ");
scanf("%d %d",&minRange, &maxRange);
for(int i=minRange; i<=maxRange; i++)
{
if(i%2!=0) sum += i;
}
printf("Sum of odd numbers from %d to %d is: %d",
minRange, maxRange, sum);
return 0;
}
Output:-
Enter min and max value of the range: 10 20
Sum of odd numbers from 10 to 20 is: 75
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