Programming Example

Square Root of Prime Number using Command Line Argument

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The square root of a Prime number by checking first if it is a prime number?

Write a C program which will check whether a given number N is a Prime or Not. If the Number N is a Prime, then find it’s square root and print that value to the STDOUT as floating point number with exactly 2 decimal precision. If the number is not Prime, then print the value 0.00 to STDOUT. The given number will be positive non zero integer and it will be passed to the program as first command line argument. Other than floating point No other information should be printed to STDOUT.

Program Code

#include<stdio.h>
#include<stdlib.h>
#include<stdbool.h>
#include<math.h>
bool isPrime(int n)
{
    if(n<2)
    return false;
    
    int i;
    for(i=2;i*i<=n;i++)
    {
        if(n%i==0)
        return false;
    }
    return true;
}


int main(int argc, char *argv[])
{
    if(argc==1)
    {
        printf("No arguments");
        return 0;
    }
    else
    {
        int n;
        n=atoi(argv[1]);
        float sq=0;
        
        if(isPrime(n))
        {
            sq=sqrt(n);
            printf("%.2f",sq);
        }
        else
        printf("%.2f",sq);

    return 0;
    }
}

Output

13

3.16

Explanation

Nope

How to learn from this program

First read the algorithm, then study the program code line by line. After that, compare the code with the output and finally go through the explanation. This approach helps learners understand both the logic and the implementation properly.

Practice suggestion

After understanding this example, try to rewrite the same program without looking at the code. Then change some values or logic and run it again. This helps improve confidence and keeps learners engaged on the page for longer.