Write a program that checks whether given number is perfect or not?

Answer 1

#include<stdio.h>

#include<conio.h>

void main()

{

int n,i,r,count=0;

clrscr();

printf("Enter a number");

scanf("%d",&n);

for(i=2;i<n;i++)

{

r=n%i;

if(r==0)

{

count++;

break;

}

}

if(count==0 && n!=1)

{

printf("It is a Prime number");

}

else

{

printf("It is not a prime number");

}

getch();

}

Answer 2

#include<stdio.h>

#include<conio.h>

void main()

{

int num,i;

clrscr();

printf("\nEnter any number:");

scanf("%d",&num);

i=2;

while(i<=num-1)

{

if(num%i==0)

{

printf("\nNumber is not prime.");

break;

}

i++;

}

if((i==num)(num==1))

printf("\nNumber is prime.");

getch();

}

Answer 3

#include
#include
void main()
{
int j,n;
clrscr();
printf("Enter the number:");
scanf("%d",&n);
j=2;
while(j<=n)
{
if(n%j==0)
break;
j++;
}
if(j==n)
printf("%d is Prime",n);
else
printf("%d is Not Prime",n);
getch();
}

Answer 4

#include<stdio.h>

// returns true if num is non-zero and is equal to

// the sum of all its proper positive divisors.

bool is_perfect (unsigned num)

{

unsigned div=0, sum=0;

while(++div<num)

if(num%div==0)

sum+=div;

return num && num==sum;

}

void main()

{

unsigned n;

printf("Enter a number: ");

scanf("%d",&n);

if(is_perfect(n))

printf("The number %d is perfect\n", n);

else

printf("The number %d is not perfect\n", n);

}

Answer 5

#include<stdio.h>

bool is_prime (const unsigned int num) {

if (num<2) return false;

if (!(num%2)) return num==2;

unsigned int max_factor = sqrt (num) + 1;

unsigned int factor;

for (factor=3; factor<max_factor; factor+=2)

if (!(num%factor)) return false;

return true;

}

int main (void) {

printf ("Input a number: ");

unsigned int num;

scanf("%d", num);

if (num<0) num*=-1; /* ensure num is positive */

if (is_prime (num))

printf ("The number is prime\n");

else

printf ("The number is composite\n");

return 0;

}