A way to find very large prime numbers?

Question

Algorythms and, if possible, code needed!

Answer 1

just change the range in the for in the main to your range of numbers.
code in Java:

package test;

public class gfhugdsau
{
public static void isprime(int num){
boolean flag = false;
for(int i = 2; i <= num/2;i++)
{
if(num==i){
continue;
}
if(num % i == 0)
{
flag = true;
break;
}
}
if (!flag){
System.out.println(num + " is a prime number.");
}
}

public static void main(String[] args)
{
for(int i=1000;i<100000;i++){
isprime(i);
}

}

}

Answer 2

Ehr.... I meant, prime numbers with thousands of digits

Answer 3

@Paolo De Nictolis
java will give you a error for this type of number..
unfortuntly, java can't handle with number with more than 10 digits.
this is the best we can do :

package test;

public class gfhugdsau
{
public static void isprime(long num){
boolean flag = false;
for(int i = 2; i <= num/2;i++)
{
if(num==i){
continue;
}
if(num % i == 0)
{
flag = true;
break;
}
}
if (!flag){
System.out.println(num + " is a prime number.");
}else{
System.out.println("efew");
}
}

public static void main(String[] args)
{
String str="1";
for(int j=0;j<9;j++){
str = str+"0";
}
long x=Integer.valueOf(str);
for(long i=x;i<x+100000;i++){
isprime(i);
}

}

}

Answer 4

Consider this, Paolo De Nictolis. The largest possible datatype for *positive* numbers is ulong and even *that* can only hold 20 digits

To get any bigger you will need a system akin to a long-adder