# TCS Coding Practice Question | Checking Prime Number

Given a number N, the task is to check if N is a Prime Number or not using Command Line Arguments.
Examples:

`Input: N = 7Output: YesInput: N = 15Output: No`

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/2+1, using a variable say i.
In each iteration,
• Check if i divide N completely (i.e. if it is a factor of N).
• If yes, then N is not a prime number.
• If no, then N is a prime number.
• After the loop has ended, it is found out that N is prime or not.

Note: Please note that 1 is not checked in this scenarios because 1 is neither 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;` `}`   `// 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[1]);`   `        ``// Check if n is prime` `        ``if` `(isPrime(n) == 1)` `            ``printf``(``"Yes\n"``);` `        ``else` `            ``printf``(``"No\n"``);` `    ``}`   `    ``return` `0;` `}`

## Java

 `// Java program to reverse a string` `// 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``;` `    ``}`   `    ``// 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``]);`   `            ``// Check if n is prime` `            ``if` `(isPrime(n) == ``1``)` `                ``System.out.println(``"Yes"``);` `            ``else` `                ``System.out.println(``"No"``);` `        ``}` `        ``else` `            ``System.out.println(``"No command line "` `                               ``+ ``"arguments found."``);` `    ``}` `}`

## Python3

 `import` `sys`   `# checking prime or not` `def` `is_prime(number):` `    ``if` `number <``=` `1``:` `        ``return` `False`   `    ``sqrt_number ``=` `int``(number ``*``*` `0.5``)`   `    ``# Loop to check if number has any factor` `    ``# other than 1 and number itself`   `    ``for` `i ``in` `range``(``2``, sqrt_number ``+` `1``):` `        ``# Since i is a factor of number` `        ``# number is not prime` `        ``if` `number ``%` `i ``=``=` `0``:` `            ``return` `False`   `    ``return` `True`   `if` `__name__ ``=``=` `"__main__"``:`   `    ``# Check if length of argv is not equal to 2` `    ``if` `len``(sys.argv) !``=` `2``:` `        ``print``(``"Usage: python prime_check.py "``)` `        ``sys.exit(``1``)`   `    ``# Get the command line argument and` `    ``# Convert it from string type to integer type` `    ``# using function "int(sys.argv[1])"` `    ``number ``=` `int``(sys.argv[``1``])`   `    ``if` `is_prime(number):` `        ``print``(number, ``"is prime."``)` `    ``else``:` `        ``print``(number, ``"is not prime."``)`   `#puligokulakishorereddy`

Output:

• In C:

• In Java:

• In Python

Time Complexity: O(N)
Auxiliary Space: O(1)

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