# Java: Get the position of a given prime number

## Java Basic: Exercise-198 with Solution

Write a Java program to calculate the position of a given prime number.

Visual Presentation:

Sample Solution:

Java Code:

``````// Import Scanner class from java.util package for user input
import java.util.*;

// Main class for the solution
public class Solution {
// Main method to execute the solution
public static void main(String[] args) {
// Create a Scanner object for user input
Scanner in = new Scanner(System.in);

// Prompt the user to input a prime number
System.out.print("Input a prime number: ");

// Read the user input as an integer
int n = in.nextInt();

// Display the position of the given prime number using the kth_Prime function
System.out.print("Position of the said Prime number: " + kth_Prime(n));
}

// Function to find the position of a given prime number in the sequence of primes
public static int kth_Prime(int n) {
// Array to store prime numbers, initialized with the first prime number (2)
int[] prime_num = new int[10000];
int num = 3;  // Starting from the next number after 2
int i = 0, index = 0;  // Variables for iteration and index tracking
prime_num[0] = 2;  // Initialize the first prime number in the array

// Continue finding primes until reaching the input number
while (num <= n) {
// Iterate through the existing primes to check if num is divisible
for (i = 0; i <= index; i++) {
if (num % prime_num[i] == 0) {
break;
}
}

// If num is not divisible by any existing primes, add it to the array
if (i > index) {
prime_num[++index] = num;
}

// Move on to the next number
num++;
}

// Return the position of the input prime number in the sequence
return index + 1;
}
}
```
```

Sample Output:

```Input a prime number:  13
Position of the said Prime number: 6
```

Flowchart:

Java Code Editor:

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