Displaying prime number using for loop in python.The output is repeating-CodePudding

Why is output repeating?

lower = int(input("enter lower interval: "))
upper = int(input("enter upper interval: "))
for num in range(lower,upper):
    if num>1:
        for i in range(2,num):
            if (num % i)  == 0:
                break
            
            else:
                print(num)

Output:

enter lower interval: 2
enter upper interval: 15
3
5
5
5
7
7
7
7
7
9
11
11
11
11
11
11
11
11
11
13
13
13
13
13
13
13
13
13
13
13

CodePudding user response：

You should write the else statement for the for loop, not the if statement

upper = int(input("enter upper interval: "))
for num in range(lower,upper):
    if num>1:
        for i in range(2,num):
            if (num % i)  == 0:
                break
            
        else:
            print(num)

CodePudding user response：

It repeats because of having there are multiple numbers that can not divide that number in the given range. Try this hope will work:

lower = int(input("enter lower interval: "))
upper = int(input("enter upper interval: "))
for num in range(lower,upper):
  is_prime = True
  if num > 1:
     for i in range(2, num):
        if (num % i) == 0:
            is_prime = False            
  if is_prime == True:
    print(num)

I have checked if it pass the condition of if (num % i) == 0: then the number is not Prime