Question

In this assignment you are asked to write a Python program to determine all the prime numbers in between a range and store them in a list that will be printed when the range is searched. The user is prompted for two positive integer values as input, one is the start of the range and the other is the end of the range. If the user gives a negative value or enters a second number that is lower than the first input value, re-prompt them to enter a correct value. Both the start and the end input values should be inclusive in the range.

Hints:

1. Use a for loop to iterate through the range.

2. You can use a while or for loop to check whether a number is prime or not, but you must create a function to test whether an integer is prime or not. To do that, divide every number in the range by 2 up through half the number. If any of those divides evenly into your test number, the number is not prime and the function returns a Boolean ‘False’. Otherwise, it is prime and the function returns ‘True’.

3. If the function returns ‘True’ for a number, append it to the list.

4. After the end of the range is reached, print the list by iterating using a ‘for’ loop.

5. Start by writing code to use a range of 0 to some number (i.e. 0 to 25), then when your tests show that works add the starting range value (i.e. 20 to 100).

Please make it simple to read as possible. I'm a beginner.

Answer 1

def isPrime(n):
#deal with some starting cases
if n==1:
return False
for i in range(2,n//2+1):
if n%i==0:#if remainder is 0, that is the number is divisible
return False
return True#if we reach here, it means we did not find any divisor
  
num1=int(input('Enter starting number: '))
while num1<1:#this loop will run as long as num1 is less than 1
print('Please enter a positive number')
num1=int(input('Enter starting number: '))
num2=int(input('Enter ending number: '))
while num2<1 or num2<=num1:#this loop will run as long as num2 is less than 1 or 1
print('Please enter a positive number greater than '+str(num1))
num2=int(input('Enter starting number: '))
  

primes=[]
for i in range(num1,num2+1):
if isPrime(i):
primes.append(i)

#printing the list
for i in primes:
print(i,end=' ')

Answer 2

Program

Primes.py

"""
Python program to determine all the prime numbers in given range
"""

def isPrime(n) :

"""
Function that checks if the given number is prime
"""
  
# Corner cases
if (n <= 1) :
return False
if (n <= 3) :
return True
  
# This is checked so that we can skip
# middle five numbers in below loop
if (n % 2 == 0 or n % 3 == 0) :
return False
  
i = 5
while(i * i <= n) :
if (n % i == 0 or n % (i + 2) == 0) :
return False
i = i + 6
  
return True

# printing Introduction
print("\nThis program prints all the prime number in a given range\n")

# reading start of the range
range_start = int(input("Enter the starting value of the range : "))

# reading end of the range
range_end = int(input("Enter the ending value of the range : "))

if(range_start < 0 | range_end < 0 | range_end < range_start):
  
# reading start of the range
range_start = int(input("Enter the starting value of the range : "))

# reading end of the range
range_end = int(input("Enter the ending value of the range : "))

# empty list to store the prime numbers
primes = []

# both the values are inclusive
# looping over the values within the range
for number in range(range_start, range_end+1):

# check if the number is prime
if(isPrime(number)):

# if the number is prime append to the list
primes.append(number)

# printing the list of prime number in the given range
print("Prime Number in the given range are : ", primes)

output:

This program prints all the prime number in a given range

Enter the starting value of the range : 20
Enter the ending value of the range : 100
Prime Number in the given range are : [23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97]

Hope this helps!

Please let me know if any changes needed.

Thank you!