# TCS Coding Practice Question | Prime Numbers upto N

Given a number N, the task is to find the Prime Numbers from 1 to N using Command Line Arguments.

Examples:

```Input: N = 7
Output: 2, 3, 5, 7

Input: N = 13
Output: 2, 3, 5, 7, 11, 13
```

Approach:

• Since the number is entered as Command line Argument, there is no need for a dedicated input line
• Extract the input number from the command line argument
• This extracted number will be in String type.
• Convert this number into integer type and store it in a variable, say N
• Now loop through the numbers from 2 to N, using a variable say i, to check if they are prime or not. This is done as follows:
In each iteration,

• Check if any numbers from 2 to (i/2+1) divide i completely (i.e. if it is a factor of i).
• If yes, then i is not a prime number. Hence check for next number
• If no, then i is a prime number. Hence print the value of i and check for next number
• After the loop has ended, the prime numbers from 1 to N are printed on the screen.

Note: Please note that 1 is not checked in this scenarios because 1 is niether prime nor composite.

Program:

## C

 `// C program to find ` `// the Prime Numbers from 1 to N ` `// using command line arguments ` ` `  `#include ` ` `  `#include /* atoi */ ` ` `  `// Function to check if x is prime ` `int` `isPrime(``int` `x) ` `{ ` `    ``int` `i; ` ` `  `    ``// Loop to check if x has any factor ` `    ``// other than 1 and x itself ` `    ``for` `(i = 2; i < x / 2 + 1; i++) { ` `        ``if` `(x % i == 0) { ` `            ``// Since i is a factor of x ` `            ``// x is not prime ` `            ``return` `0; ` `        ``} ` `    ``} ` ` `  `    ``// x is prime ` `    ``return` `1; ` `} ` ` `  `// Function to find prime numbers up to n ` `void` `findPrimes(``int` `n) ` `{ ` `    ``int` `i; ` ` `  `    ``// Loop from 2 to n ` `    ``// to find all prime numbers in between ` `    ``for` `(i = 2; i <= n; i++) { ` ` `  `        ``// Check if i is prime ` `        ``// If yes then print it ` `        ``// else continue to next number ` `        ``if` `(isPrime(i) == 1) ` `            ``printf``(``"%d, "``, i); ` `    ``} ` ` `  `    ``printf``(``"\n"``); ` `} ` ` `  `// Driver code ` `int` `main(``int` `argc, ``char``* argv[]) ` `{ ` ` `  `    ``int` `n; ` ` `  `    ``// Check if the length of args array is 1 ` `    ``if` `(argc == 1) ` `        ``printf``(``"No command line arguments found.\n"``); ` `    ``else` `{ ` ` `  `        ``// Get the command line argument and ` `        ``// Convert it from string type to integer type ` `        ``// using function "atoi( argument)" ` `        ``n = ``atoi``(argv); ` ` `  `        ``// Find all prime numbers upto n ` `        ``findPrimes(n); ` `    ``} ` `    ``return` `0; ` `} `

## Java

 `// Java program to find ` `// the Prime Numbers from 1 to N ` `// using command line arguments ` ` `  `class` `GFG { ` ` `  `    ``// Function to check if x is prime ` `    ``public` `static` `int` `isPrime(``int` `x) ` `    ``{ ` `        ``int` `i; ` ` `  `        ``// Loop to check if x has any factor ` `        ``// other than 1 and x itself ` `        ``for` `(i = ``2``; i < x / ``2` `+ ``1``; i++) { ` `            ``if` `(x % i == ``0``) { ` `                ``// Since i is a factor of x ` `                ``// x is not prime ` `                ``return` `0``; ` `            ``} ` `        ``} ` ` `  `        ``// x is prime ` `        ``return` `1``; ` `    ``} ` ` `  `    ``// Function to find prime numbers up to n ` `    ``public` `static` `void` `findPrimes(``int` `n) ` `    ``{ ` `        ``int` `i; ` ` `  `        ``// Loop from 2 to n ` `        ``// to find all prime numbers in between ` `        ``for` `(i = ``2``; i <= n; i++) { ` ` `  `            ``// Check if i is prime ` `            ``// If yes then print it ` `            ``// else continue to next number ` `            ``if` `(isPrime(i) == ``1``) ` `                ``System.out.print(i + ``", "``); ` `        ``} ` ` `  `        ``System.out.println(); ` `    ``} ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `main(String[] args) ` `    ``{ ` ` `  `        ``// Check if length of args array is ` `        ``// greater than 0 ` `        ``if` `(args.length > ``0``) { ` ` `  `            ``// Get the command line argument and ` `            ``// Convert it from string type to integer type ` `            ``int` `n = Integer.parseInt(args[``0``]); ` ` `  `            ``// Find all prime numbers upto n ` `            ``findPrimes(n); ` `        ``} ` `        ``else` `            ``System.out.println(``"No command line "` `                               ``+ ``"arguments found."``); ` `    ``} ` `} `

Output:

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.

My Personal Notes arrow_drop_up Content Manager at LambdaTest

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.

Article Tags :
Practice Tags :

1

Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.