# Prime numbers upto 100

What is a prime number ?
Integer Greater than 1
Its only factor is 1 and itself.

It should not be divisible ( with reminder equal to 0 ) by any number less than it and greater than 1.
We will be using fmod() or % operator to get reminder of any division.

First we will use while loop to display all the number between 2 and our given number ( 100 ).
``````while (i<=my_num){
// statements
}``````
We will use one flag and set the value to 0 at the beginning of each loop.
``````while (i<=my_num){
flag=0;
}``````
By using a for loop we will divide each number by all number starting from 2 and ending one less than the number.
`````` for(j=2;j<=i-1;j++){
if(i % j == 0 ){
flag=1;
break;
}
}``````
At any point inside the for loop if the reminder of division became 0 then we will exit the for loop and set the flag to 1 . That will indicate that the number is not a prime number.
Before starting the next loop we will reset the flag to 0 again as shown above. We used one if condition to check the flag value and display the message if it is equal to 0;
Here is the complete code
``````#include<stdio.h>
#include<string.h>
int main()
{
int my_num=100;
int i=2,j;
int flag=0;
while (i<=my_num){
flag=0;

for(j=2;j<=i-1;j++){
if(i % j == 0 ){
flag=1;
break;
}
} // end of for loop
if(flag==0){
printf( " %d is a prime number  \n",i);
}
i++;
} // end of while loop
return 0;
}``````
Numbers other than Prime numbers will have factors , we can list the factors of a given number.

## Subscribe

* indicates required
Subscribe to plus2net plus2net.com