a loop-based user input prime/composite number checker

Here are the steps for the approach used in the R program to find whether a given number is prime or composite:

Define a function is_prime(n) that takes a positive integer n as input and returns TRUE if n is prime and FALSE otherwise.
To determine whether n is prime, check if it is less than or equal to 1 and return FALSE if it is.
Then, iterate over all integers i from 2 to the square root of n, and check if n is divisible by i. If n is divisible by i, return FALSE, since this means that n is composite.
If no divisors are found, return TRUE, since n is prime.
Use a loop to repeatedly prompt the user to enter a positive integer, until they enter a non-positive integer (e.g., 0).
For each input number n, call the is_prime(n) function to determine whether it is prime or composite.
Print out a message indicating whether n is prime or composite, using the cat() function.
Repeat steps 2-4 until the user enters a non-positive integer.

R

is_prime <- function(n) {
  if (n <= 1) {
    return(FALSE)
  }
  for (i in 2:(sqrt(n))) {
    if (n %% i == 0) {
      return(FALSE)
    }
  }
  return(TRUE)
}
 
while (TRUE) {
  n <- as.integer(readline("Enter a number (enter 0 to exit): "))
  if (n == 0) {
    break
  }
  if (is_prime(n)) {
    cat(n, "is prime\n")
  } else {
    cat(n, "is composite\n")
  }
}

Enter a number (enter 0 to exit): 2
2 is prime
Enter a number (enter 0 to exit): 4
4 is composite
Enter a number (enter 0 to exit): 5
5 is prime
Enter a number (enter 0 to exit): 0

Time complexity: O(q * sqrt(n))

auxiliary space: O(1)

R program to find prime and composite numbers in an interval

A natural number (1, 2, 3, 4, 5 and so on) is called a prime number if it is greater than 1 and cannot be written as the product of two smaller natural numbers. The numbers greater than 1 that are not prime are called composite numbers.

A composite number is a positive integer that can be formed by multiplying two smaller positive integers. Equivalently, it is a positive integer that has at least one divisor other than 1 and itself.

Example:

Input: 2

Output: Prime

Explanation: it is divisible by only 2 so prime.

Input: 4

Output: Composite

Explanation: it is divisible by 2 and 4 so composite.

Input: 5

Output: Prime

Explanation: it is divisible by only 5 so prime.

Algorithm:

Initialize the range till where prime and composite numbers to be displayed.
Create a separate empty lists to store prime and composite numbers.
Since 1 is neither prime nor composite,
We start checking condition for prime from 2 as i.
Starting from 2 checks each and every digit that divides i exactly
If No number divides i except that i then number gets stored in prime number list,
Else gets stored in composite number list.
It executes till n(given by us) limit reaches.
Once it exits from loop, it prints both prime and composite numbers as separate list.

Example:

R

# R code for Finding composite  and prime numbers  upto 100
# initialize number n
n=100
 
# arranging sequence
x = seq(1, n)
 
# creating an empty place to store the numbers
prime_numbers=c()
 
composite_numbers = c()
for (i in seq(2, n)) {
  if (any(x == i)) {
 
    # prime numbers gets stored in a sequence order
    prime_numbers = c(prime_numbers, i)
    x = c(x[(x %% i) != 0], i)
  }
 
  else{
 
     # composite numbers gets stored in a sequence order
     composite_numbers = c(composite_numbers, i)
  }
}
 
# printing the series
print("prime_numbers")
print(prime_numbers)
 
print("composite_numbers")
print(composite_numbers)

Output:

[1] “prime_numbers”

[1] 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

[1] “composite_numbers”

[1] 4 6 8 9 10 12 14 15 16 18 20 21 22 24 25 26 27 28 30

[20] 32 33 34 35 36 38 39 40 42 44 45 46 48 49 50 51 52 54 55

[39] 56 57 58 60 62 63 64 65 66 68 69 70 72 74 75 76 77 78 80

[58] 81 82 84 85 86 87 88 90 91 92 93 94 95 96 98 99 100

The time complexity of this code is O(n^2) since there is a nested loop in the function.

The auxiliary space used by this code is O(n)

Tags:

#Prime Number #Misc #R Language #Misc #Prime Number

Method 2

a loop-based user input prime/composite number checker

R

R program to find prime and composite numbers in an interval

R

Similar Reads

Contact Us