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, 7Input: 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 neither prime nor composite.
Program:
C
// C program to find // the Prime Numbers from 1 to N // using command line arguments #include <stdio.h> #include <stdlib.h> /* 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[1]);
// 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:
- In C:
- In Java:
Time Complexity: O(N*N)
Auxiliary Space: O(1)