This article shows *how to write a C or C++ program to show prime numbers between a Range. *Before start let us discuss about the prime numbers.

**What is Prime Number?**

In mathematics Prime Number are those number whose can be divided evenly only by 1, or itself. It must be a whole number greater than 1. For example: 5 can only be divided evenly by 1 or 5, so it is a prime number. 6 can be divided evenly by 1, 2, 3 and 6. So 6 is not a prime number. it is a composite number.

The first few prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23. There is no largest prime number. For every prime number p there exists a prime number p’ such that p’ is greater than p. This number was demonstrated in ancient times by the Greek mathematician Euclid.

**Program to Show Prime Numbers between Range**

#include

#include

#include

int main(){

clrscr();

int i,j,n,f,k=0; cout<<” ” This program will show Prime numbers between a range. “”<<endl<<endl;

xx:

cout<<“How many numbers ? Give a integer number.”<<endl;

cin>>n;

if(n<0) {

cout<<“Negative number not allow,Please give a positive number.”<<endl<<endl;

goto xx;

}

cout<<endl;

cout<<“Prime numbers between 1 to “<<n<<” are :”<<endl;

for(i=1;i<=n;i++) {

f=0;

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

if ((i%j)==0) f=1;

if (f==0) {

cout<<i<<” “;

k++;

}

}

if (k==0) {

cout<<0;

}

getch();

}

Its a good program.Thanks