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write a program to find out whether a given number is prime...

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Question by urvi
Submitted on 1/1/2004
Related FAQ: comp.lang.c Answers to Frequently Asked Questions (FAQ List)
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write a program to find out whether a given number is prime or not.


Answer by golla.satyanarayana
Submitted on 3/17/2004
Rating:  Rate this answer: Vote
main()
{
int a,c=0,i,n;
printf("enter the number to be checked");
scanf("%d",&n);
for(i=1;i<=n;i++)
   {
     a=n%i;
     if(a=0)
        {
           c=c+1;
        }
    }
if (c=2)
  { printf("the given number is prime"); }
else
    printf("the given number is not prime");
}

 

Answer by Abhilash
Submitted on 1/28/2005
Rating:  Rate this answer: Vote
#include<stdio.h>
#include<conio.h>
void main()
{
int no,i;
clrscr();
printf(" Enter the Number U want to check:");
scanf("%d",&no);
i=2;
while(i<=no-1)
{
if(no%i==0)
  {
    printf(" %d is not Prime number",no );
    break;
  }
i=i+1;
}
if(no==i)
  printf("%d is a prime Number",no);
getch();
}

 

Answer by james
Submitted on 2/9/2005
Rating: Not yet rated Rate this answer: Vote
main()
{
int n,i,a;
printf("enter the number");
scanf("%d",&n);
if(n==1)
printf("it is neither prime nor composite");
for(i=2;i<=n;i++)
{
a=n%i;
if(a==0)
{
printf("the number is not a prime number");
}
else
{
printf("the number is prime");
}
}
}

 

Answer by naveen
Submitted on 5/19/2005
Rating: Not yet rated Rate this answer: Vote
void main()
{
int i,n;
printf("enter the number to be checked");
scanf("%d",&n);
for(i=2;i<=n;i++)
   {
     if(n%i==0)
     printf("The number is prime number")
}
       else
   printf("the given number is not a prime number");
getch();
}

 

Answer by goli
Submitted on 2/16/2006
Rating: Not yet rated Rate this answer: Vote
main()
{
int n, i;
printf ("Enter any number \n");
scanf("%d", &n);
for (i=2 ; i <=n/2 ; i++)
   {
     if(n % i ==0)
     {
        printf(" Its not a prime number\n");  
        break;
     }

   }
   printf("Its a prime number\n ");
}

 

Answer by romeo
Submitted on 2/20/2006
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#include<stdio.h>
#include<conio.h>
#define TRUE 1
#define FALSE 0

int prime(int number)
{
   int i=2,flg=TRUE,c;
   while(i<number)
   {
      c = number %i;
      if(c==0)
         flg=FALSE;
      i++;
   }
   return flg;
}

void main()
{
   int num,c;
   int is_prime;
   clrscr();
   printf("Enter a number: ");
   scanf("%d",&num);

   is_prime = prime(num);

   if(is_prime==1)
      puts("Prime Number");
   else
      puts("Not a Prime Number");
   getch();
}



 

Answer by supriya
Submitted on 3/29/2006
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main()
{
int a,c=0,i,n;
printf("enter the number to be checked");
scanf("%d",&n);
for(i=1;i<=sqrt(n);i++)
   {
     a=n%i;
     if(a=0)
        {
           c=c+1;
        }
    }
if (c=2)
  { printf("the given number is prime"); }
else
    printf("the given number is not prime");
}

 

Answer by raihana66
Submitted on 5/16/2006
Rating: Not yet rated Rate this answer: Vote
int n,n1;
print("enter number");
scanf("%i",&n);
if(n%2=0&&n1=2)
printf("prime number");
else
printf("not primenumber);

 

Answer by raihana66
Submitted on 5/16/2006
Rating: Not yet rated Rate this answer: Vote
int n,n1;
printf("enter number");
scanf("%i",&n);
if(n%2=1&&n1=2)
printf("prime number");
else
printf("not prime number);

 

Answer by raihana66
Submitted on 5/16/2006
Rating: Not yet rated Rate this answer: Vote
int n,c);
printf("enter number");
scanf("%i",&n);
if(n%2=0&&n>=1&&c=2)
printf("prime number");
else
printf("not prime number);

 

Answer by raihana
Submitted on 5/16/2006
Rating: Not yet rated Rate this answer: Vote
main()
{
int a,c,i,n;
printf("enter the number to be checked");
scanf("%d",&n);
if(i=1&&i<=n&&i++)
    
     a=n%i;
     if(a=0)
        {
           c=c+1;
        }
    }
if (c=2)
   printf("the given number is prime");  
else
  printf("the given number is not prime");
}





 

Answer by SATINDRA MOHAN
Submitted on 7/19/2006
Rating: Not yet rated Rate this answer: Vote
main()
{
int a,c=1,i,n;
printf(" NUMBER = ");
scanf("%d",&n);
for(i=1;i<=n;i++)
   {
     a=n%i;
     if(a==0)
        {
           c=c+1;
        }
    }
   if (c==3)
    printf(" PRIME NUMBER");  
    else
    printf(" NOT PRIME NUMBER");

getch();
}

 

Answer by priya
Submitted on 7/23/2006
Rating: Not yet rated Rate this answer: Vote
4 IS NOT A PRIME

 

Answer by Sudhakar Desaboina
Submitted on 8/23/2006
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main()
{
int a,c=0,i,n;
printf("enter the number to be checked");
scanf("%d",&n);
for(i=1;i<=n;i++)
   {
     a=n%i;
     if(a==0)
        {
           c=c+1;
        }
    }
if (c==2)
    printf("the given number is prime");
else
    printf("the given number is not prime");
}

 

Answer by Santosh
Submitted on 8/31/2006
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// program for finding prime number

#include<stdio.h>

int isPrime(int n)
{
   int i,j;
   i=1;
   j=0;
   while(i<=n)
   {
      if(n%i==0)   
         j++;
      i++;
   }
   if(j==2)   
   {
      printf("Prime");
      return 1;
   }
   else
   {
      printf("Not Prime");
      return 1;
   }
}
int main()
{
   int num;
   printf("Enter Number : ");
   scanf("%d",&num);
   isPrime(num);
   return 1;
}

 

Answer by sumanth
Submitted on 11/10/2006
Rating: Not yet rated Rate this answer: Vote
main()
{
int a,c=0,i,n;
printf("enter the number to be checked");
scanf("%d",&n);
for(i=1;i<=n;i++)
   {
     a=n%i;
     if(a==0)
        {
           c=c+1;
        }
    }
if (c==2)
  { printf("the given number is prime"); }
else
    printf("the given number is not prime");
}





 

Answer by neeraj
Submitted on 11/11/2006
Rating: Not yet rated Rate this answer: Vote
main()
{
int a,c=0,i,n;
printf("enter the number to be checked");
scanf("%d",&n);
for(i=1;i<=n;i++)
   {
     a=n%i;
     if(a==0)
        {
           c=c+1;
        }
    }
if (c==2)
  { printf("the given number is prime"); }
else
    printf("the given number is not prime");
}

 

Answer by sundar
Submitted on 12/29/2006
Rating: Not yet rated Rate this answer: Vote
#include <stdio.h>
main ()
{
  int i, j, prime = 0;
  for (i = 1; i < 1000; i++)
    {
      prime = 0;
      for (j = 2; j < (i / 2) + 1; j++)
        {
          if (i % j == 0)
            {
              prime = 1;
              break;
            }
        }
      if (prime == 0)
        {
          printf ("%d is a prime number\n", i);
        }
    }
}                

 

Answer by Shiwani
Submitted on 1/14/2007
Rating: Not yet rated Rate this answer: Vote
main()
{
  int i,n,rem,sq;
  
  printf("enter the number to be checked");
  scanf("%d"&n);
  sq=sqrt(n);
  for(i=2,i<=sq,i++)do
  {
     rem=n%i;
     if(rem==0)
     {
       printf("given number is not prime");
       exit;
     }
  }
  printf("given number is prime");
}
        
  

 

Answer by Arjun
Submitted on 1/23/2007
Rating: Not yet rated Rate this answer: Vote
int main ()
{
int r,n;
printf("Enter a number to be checked : ");
scanf("%d",&n);
for(r=2;r<=n;r++)
{
if(n%r==0)
{
if(r < n)
{
printf("It is not a prime number\n");
break;
}
else
printf("It is a prime number\n");
}
}
}

 

Answer by fearfact_53
Submitted on 2/9/2007
Rating: Not yet rated Rate this answer: Vote
This program runs, if you enter a add number that is not prime it will tell you that it is a prime number. Any way nice try. Email me if you want 1 that works. ( fearfact_53@yahoo.com)

 

Answer by KDW
Submitted on 2/19/2007
Rating: Not yet rated Rate this answer: Vote
// This program determines the nearest prime numbers
// Written in C++
// By: KDW
// Febuary 1, 2007
// Several revisions are included in this edition
/*
        1. As soon as a remainder of 0 is encountered the
        program moves on to the next incremented value above
        or below the seed.
        2. When testing whether a particular seed is a prime
        the program only test up to 1/2 of the seed value.
        3. Displays how many iterations were needed to produce
        the result.
*/

#include <iostream>
using namespace std;

int main()
{
  long seed, seed2, seed3, pnum, dnum, rem, counter, counter2;
  bool prime, prime2;

  // Let the user test multiple values
  for (seed3 = -1; seed3 != 0; )
  {
  counter = counter2 = 1;
  if(seed3 >= 0)
        seed = seed3;
  else
  {cout << "Enter a number and I will tell\n"
       << "you it's nearest prime number.\n";
  cin >> seed;}
  // Prevent the user from entering a negative number
  while (seed <= 0)
  {
     cout << "Please enter a valid number (greater than 0)!\n";
     cin >> seed ;
  }
  // Automatically says user's value is prime if they enter 1
  if (seed == 1)
       cout << seed << " is the smallest prime number!\n"
            << "2 is the nearest larger prime number!\n";
  else if (seed == 2)
       cout << seed << " is a prime number!\n";
  else
  {
  seed2 = seed ; // Defines the seed number for the smaller primes

// Finds the nearest lager prime
        for (prime = 0 ; prime != 1 ; seed++)
        {
  // Tests whether number is a prime
                dnum = 2          ;
                rem = seed % dnum ;
                if (rem == 0)
                         prime = 0;
                else
                {
                  for (pnum = seed, dnum = 3, prime = 1 ; dnum <= (pnum  / 2) && prime != 0; dnum += 2)
                    {
                        rem = pnum % dnum ;
                        if (rem == 0)
                            prime = 0;
                        counter++;
                    }
                }
        }
  // Finds the nearest smaller prime
        for (prime2 = 0 ; prime2 != 1 ; seed2--)
        {
  // Tests whether number is a prime
                dnum = 2          ;
                rem = seed2 % dnum ;
                if (rem == 0)
                   prime2 = 0;
                else
                {
                   for (pnum = seed2, dnum = 3, prime2 = 1 ; dnum <= (pnum / 2) && prime2 != 0 ; dnum += 2)
                    {
                        rem = pnum % dnum ;
                        if (rem == 0)
                           prime2 = 0;
                        counter2++ ;
                    }
                }
        }
  cout << --seed << " is the nearest larger prime number!\n";
  cout << ++seed2 << " is the nearest smaller prime number!\n";
  cout << counter + counter2 << " calculations";
  }
  cout << "\nEnter another number (type '0' to quit)\n" ;
  cin >> seed3;
  cout << endl;
  }
   return 0;
}

 

Answer by kiran vellanki
Submitted on 3/27/2007
Rating: Not yet rated Rate this answer: Vote
int main()
{
int a,b,c,d=0;
printf("Enter the number : ");
scanf("%d",&a);
c=a/2;

for(b=2;b<=c;b++)
{
if  (a%b==0)
++d;
}

if (d==0 && a>0)
printf("\n\nThe number is prime");
else
printf("\n\nThe number is not prime");

}

 

Answer by vinaychimalgi
Submitted on 4/17/2007
Rating: Not yet rated Rate this answer: Vote
This will give u answer in minimum clock cycles......i'e at maximum speed...

#include<stdio.h>
#include<conio.h>
voice main()
{
int i=0,n,mod,count=0;
clrscr();
printf("/n Enter the number:- ");
scanf("%d",&n);
mod=n/2;
for(i=1;i<=mod;i++)
{
if(n%i==0)
count++;
};
if(count==1)
printf(" Number %d is prime ",n);
else
printf(" Number %d is not prime ",n);
getch();
}

 

Answer by Sathish.Ponnusamy
Submitted on 4/25/2007
Rating: Not yet rated Rate this answer: Vote
#include <stdio.h>
main()
{
       int n,i=1,j,c;
       clrscr();
       printf("Enter Number Of Terms
");
       printf("Prime Numbers Are Follwing
");
       scanf("%d",&n);
       while(i<=n)
       {
          c=0;
          for(j=1;j<=i;j++)
          {
              if(i%j==0)
              c++;
          }
           if(c==2)
           printf("%d   ",i)
           i++;
        }
        getch();
}

 

Answer by Waleed
Submitted on 6/24/2007
Rating: Not yet rated Rate this answer: Vote
Not really..

if(a=0)

if (c=2)

will always be true...

CORRECTION::

if (a==0)

if (c==0)

After doing the correction.. the program seems to work..

 

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