如何找到一个数字的质因数？花了几个小时试图弄清楚为什么 if 和 else 会同时执行

Question

''' #i want to print the prime factors of num #for the last two outputs should the else statement not run and break here.as the if condition is full filled
#if i break here how does it continue to else'''

num=147
v=0

val=0
for i in range(2,num):


    if num%i==0:

        for x in range(2,i):

            if i%x==0 :
                print(i)
                print(x)
                print(i/x)
                break    
            else:

                v = i
    else:
        continue


    print('primefacs ',v) 

Python 3.8.1 (default, Feb 2 2020, 08:37:37)

primefacs  3
primefacs  7
21
3
7.0
primefacs  21
49
7
7.0
primefacs  49

Answer 1

The else clause should be associated with the for -loop, not the if -statement in your inner loop part.

num = 147
v = 0

for i in range(2, num):
    if num % i == 0:
        for x in range(2, i):
            if i % x == 0:
                print(i)
                print(x)
                print(i / x)
                break
        # comes here if we didn't hit the `break` above
        else:
            v = i
    else:
        continue
    print('primefacs ', v)

Output:

primefacs  3
primefacs  7
21
3
7.0
primefacs  7
49
7
7.0
primefacs  7