Write a Python program to print all prime numbers in an interval?-CodePudding

Define a function that takes two integers (start, end) and classify the numbers between the range as prime and non-prime number and print the prime numbers

def is_prime(n):
    if n < 1: 
        return False 
    for i in range(2, n 1): 
        if n % i == 0: 
            return False 
    return True 
 
def print_primes(start, end): 
    for i in range(start, end): 
        if is_prime(i): 
            print(i) 
 
a=int(input("Start value: ")
b=int(input("End value: ")
print_primes(a,b)

CodePudding user response：

def is_prime(n): 
    if n < 2: 
        return False 
    for i in range(2, n): 
        if n % i == 0: 
            return False 
    return True 
 
def print_primes(start, end): 
    for i in range(start, end 1): 
        if is_prime(i): 
            print(i) 
 
a=int(input("Start value:")
b=int(input("End value:")
print_primes(a,b)

CodePudding user response：

Some bugs which are fixed.

(1) you have not closed round parameter while taking input from the user a and b

(2) is_prime(). for loop run till n-1 not till the n

(3) stored answer in res for the readability.

Code:-

def is_prime(n):
    if n < 1: 
        return False 
    for i in range(2, n): 
        if n % i == 0: 
            return False 
    return True 
 
def print_primes(start, end):
    res=[]
    for i in range(start, end): 
        if is_prime(i): 
            res.append(i)
    return res
 
a=int(input("Start value: "))
b=int(input("End value: "))
print(print_primes(a,b))

Output:

Start value: 3
End value: 13
[3, 5, 7, 11]

As you can see start value is inclusive and end value is exclusive to make both inclusive just iterated to end 1 in print_primes function

CodePudding user response：

def is_prime(n):
    if n < 1: 
        return False 
    for i in range(2, n 1):

It should be:

def is_prime(n):
    if n < 1: 
        return False 
    for i in range(2, n):

It should go till less than n, else n will always be divisible by i and return False

a=int(input("Start value:"))  # make sure to close the parenthesis
b=int(input("End value:"))    # make sure to close the parenthesis

CodePudding user response：

This takes into account the problem of float in range. Try it. :)

def is_prime(n):    
    if not n < 1:      
        for i in range(2, n): 
            if not n % i == 0:
                return True
            else:
                return False

    
def print_primes(start, end):
    res=[]
    start=int(start)
    end=int(end)
    for i in range(start, end 1):
        if is_prime(i): 
            res.append(i)
    return res
    
#a=int(input("Start value: "))
#b=int(input("End value: "))
a=0.3
b=41
print_primes(a,b) 
#[3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41]