C Prime Number

What Is Prime Number

A prime number is a whole number or a natural number greater than 1 that has no positive divisors other than 1 and itself. For example, 7 is prime number because it has no positive divisors other than 1 and 7. 6 is not a prime number because it has positive divisors such as 1, 2, 3, 6.

Prime Numbers From 1 to 100

Interesting Facts

• 0 and 1 are not considered as a prime numbers.
• 2 is the only even prime number.

C Program - Prime Number (Easy)

Let us work through a program to find whether the number is prime or not.

#include <stdio.h>
int main()
{
int num, temp, i, j = 0;
printf("Enter a number to check if it is prime : ");
scanf("%d",&num);
for ( i = 2; i <= num/2; i++ )
{
temp = num%i;
if(temp == 0)
j++;
}
if(num > 1)
{
if ( j < 1)
printf("%d is a prime number",num);
else
printf("%d is not a prime number",num);
}
return 0;
}

Enter a number to check if it is a prime number: 111
111 is not a prime number

C Program - Prime Number (Hard)

Let us work through a program to find whether the number is prime or not.

#include <stdio.h>
int main()
{
int num, a;
printf("Enter a number to check if it is prime : ");
scanf("%d",&num);
for ( a = 2;a <= num-1;a++ )
{
if ( num%a == 0 )
{
printf("%d is not a prime number\n", num);
break;
}
}
if ( a == num )
printf("%d is a prime number",num);
return 0;
}

Enter a number to check if it is a prime number: 7
7 is a prime number

Report Us

We may make mistakes(spelling, program bug, typing mistake and etc.), So we have this container to collect mistakes. We highly respect your findings.

Report

Error Line Corrected Line Send