• Lets discuss a program on how to print prime numbers from 1 to 100.
• Here by default we need to print all prime numbers from 1 to 100.
• No need to ask user to enter a number because we need to end loop at 100.
• Using for loop iterate from 1 to 100
• Take one more loop and check each number is divisible by 1 and itself or not.
• Program to print prime number between 1 to 100 in c

#1.C program to print prime numbers from 1 to 100

•  Check here for printing an integer in c 
• We have 4 basic data types in c programming language
• int, char, float and double
• For storing numbers or integers we will use int data type.
• Lets see an example program sum of two integers in c programming language.
• To add two integers we need two int type variables and third variable to store result of sum of two integers.
• Its a basic level example program for beginners to understand integer data types

• Please check this below program which prints even numbers from 1 to n.

• Print even numbers in c 
• To print sum of even numbers from 1 to n first we need to get all the even numbers and add them.
• Using for or while loop iterate from 1 to n number and get all even numbers
• sum=sum+evenNumber
• C program to find sum of even numbers using while loop

C program to find sum of even numbers using while loop

• Lets see how to write a c program to print even numbers using c programming.\
• Its a basic example to print only even numbers 
• Use for loop and iterate from 1 to n.
• In each iteration check if number if divisible by 2 (n%2 == 0). if yes then its a even number otherwise it is a odd number.
• C program to print even numbers from 1 to n. 

#2 print even numbers in c using while loop

• Now we will try to print even numbers using while loop
• Only difference is replace for with while loop
• Variable initialization will be done before loop
• condition will be inside while(condition)
• increment or decrement will be last line of while block 
• Lets print even numbers using while loop from 1 to n.

• To find sum of digits of a number in c , we need to get individual numbers and add those numbers.
• First of all read a number from user using scanf.
• Using while loop get individual number 
• Divide the number with 10 so we will get last digit of that number as remainder , once we get that last digit then add it to one variable and divide that number with 10 so it will become one digit less.
• like this we can get all digits and add all those numbers to get sum of digits 
• Sum of individual digits in c program
• c program to find sum of digits of a 3 digit number

correction: here n =number .

# program to find sum of digits of a number in c

1. #include<stdio.h> // include stdio.h
2. //c program to find sum of digits of a number using while loop
3. //write a program to find sum of digits of a number
4. //www.instanceofjava.com
5. int main()
6. {
7.     // declare variables 
8.     int number, remainder, sum = 0;
9.     //read input from user 
10.     printf("Enter a number: ");
11.     scanf("%d", &number);
12. 
    
13.    //iterate until number not equal to zero
14.    // get individual digits and add all those digits to get sum
15.     while(number != 0)
16.     {
17.         remainder = number % 10;
18.         sum += remainder;
19.         number = number / 10;
20.     }
21.   //print sum of digits in c
22.     printf("sum = %d", sum);
23. 
    
24.     getch();
25. }