PyPro # 13 Prime Number or Not

Prime Number or Not in Python: A Python program to check whether the provided number is prime or not.

Prime Number or Not in Python

# PRIME NUMBER OR NOT
# The program should contain two functions: one for concluding whether a number is prime or not; the other a main program that reads a number and displays the conclusion.

# A prime number is an integer greater than 1 that is only divisible by one and itself e.g. 2, 3, 5, 7, 11, 3, 17, 19 etc.

# INPUT: any number
# OUTPUT: conclusion if the given number is prime or not
# Also, ensure that your file when imported into another file doesn't trigger your program automatically

# THOUGHT PROCESS: Construct a function that takes an argument, and returns True or False based on logic -> 
# Declare a main function(call it anything you want) and have the user input a number -> 
# Pass the number to the declared function -> 
# Based on the value returned by the function, display the conclusion -> 
# include the bit to run the main function if the file has not been imported i.e. it has been run directly.

# function to determine whether the supplied number is prime or not.
def isPrime(num):
	if num <= 1:
		return False
	for factor in range(2, num):	# if there exists any number greater than 2 that 
		if num % factor == 0:		# divides the given number evenly(with remainder 0, that is),  
			return False			# then the given number is not prime
	return True
	
# the main function
def mainProgram():
	number = int(input("Enter the number to be tested: "))
	if isPrime(number):
		print(number, "is prime.")
	else:
		print(number, "is not prime.")

# if the file has been run directly AND not been imported, call the main function		
if __name__ == "__main__":
	mainProgram()

See also:

• Python 101
• Object Oriented Python
• Design Patterns in Python
• 50+ Handy Standard Library Modules
• 60+ Handy Third Library Modules
• 50+ Tips & Tricks for Python Developers
• 50+ Know-How(s) Every Pythonista Must Know