Question

How to write a Cprogram to print all the prime numbers between 1and n where n is the value supplied by the users.

Answer 1

Answer:

#include <stdio.h>

int main()

{

   int i, j, n, prime;

   printf("Enter till where we want to find prime number: ");

   scanf("%d", &n);

   for(i=2; i<=n; i++)

   {

       prime = 1;  

       for(j=2; j<=i/2; j++)

       {

         

           if(i%j==0)

           {

               prime = 0;

               break;

           }

       }

       if(prime==1)

       {

           printf("%d, ", i);

       }

   }

   return 0;

Explanation:

A number  which is divisible by 1 and itself is called prime number. Here in the program we start by taking number from 1 to n , where n is the last number till which we are required to find prime numbers. Then we start the loop by taking two for loops one for running the numbers from 1 to n and the inner for loop to check whether the number is divisible other than 1 and itself. We take the current number as prime =1. If the number is still not divisible by number other than 1 and itself we consider that number to be prime and print it.