## Friday, March 11, 2022

### Display Prime Numbers in Java

This post shows how you can generate and display prime numbers in Java in the given range.

A number is a prime number if can be divided either by 1 or by the number itself. So every number with in the given range has to be divided starting from 2 till number/2 in the loop. You only need to run your loop from 2 to N/2 (where N is the passed number), reason being no number is completely divisible by a number more than its half.

### Java code to display prime numbers within the given range

```import java.util.Scanner;

public class DisplayPrime {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter start number for displaying prime numbers- ");
int start = sc.nextInt();
// Since 1 and 0 are not considered prime
if(start == 0 || start == 1){
start = 2;
}
System.out.println("Enter end number for displaying prime numbers- ");
int end = sc.nextInt();
for(int i = start; i <= end; i++){
System.out.print(i + " ");
}
}
}

boolean flag = true;
for(int i = 2; i <= num/2; i++){
// No remainder means completely divides
if(num % i == 0){
flag = false;
break;
}
}
return flag;
}
}
```
Output
```Enter start number for displaying prime numbers-
1
Enter end number for displaying prime numbers-
20
2 3 5 7 11 13 17 19

Enter start number for displaying prime numbers-
20
Enter end number for displaying prime numbers-
100
23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97
```

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