Write a C program to find if the given number is a prime number or not - Online Rockers

 Good Morning viewers,

                            I am starting my day with this post. Seeing the title above , you may think weird such that how can we feed the logic to a computer to know if the entered number is a prime number or not. But the fact is that it is so simple.

How will you find if a number is a prime number or not?

                            Generally speaking , numbers above 1 can only be a prime number or a composite number . Any number which has its factors 1 and itself is called prime number. For example , 7 has its factors 1 and 7 . Hence, it is a prime number.If a number has factors other than 1 and itself then it is called Composite number.


                           Logically , we know to find a prime number , by checking if the number is divisible by any other number . Now , a doubt may arise in my mind thinking , how can a computer check this,  Don't worry , I am gonna show you how to do this.

Note:In order to compile a C program , you must have a C compiler. You can download it here for absolutely  free,

Source code:

#include<stdio.h>
int main()
{
int num,i=2;
printf("Enter the number");
scanf("%d",&num);                                             //accept number from user
while(i<=(num-1))                                               //loop to check prime number
{
if(num%i==0)
{
printf("\n It is not a prime number");
break;                                                   //printing the result
}
else
{
i++;
}
}
if(i==num)
{
printf("\n It is a prime number");                   //printing the result
}
return 0;
}

Output:

Sample output 1:

Sample output 2:

Check out other C programs:

• To check if the given number is an Armstrong number
• To find the sum of digits
• To find the sum of square series

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