为什么我收到错误：UnboundLocalError: local variable 'lcm' referenced before assignment

Question

I am trying to find the lcm of two numbers. But when I run the program, I am getting the error:

UnboundLocalError: local variable 'lcm' referenced before assignment

Why am I getting this error? I can't understand what is wrong with my code.

Here's my code:

def compute_lcm( num1, num2):
    
    if num1 > num2:
        greater = num1
        
    else:
        greater = num2
        
        for i in range(1, greater + 1):
            if ( i % num1 ) == 0 and ( i % num2) == 0:
                lcm = i
        print(lcm)
                
compute_lcm( 12, 14)

Answer 1

The error you get is because the code never satisfies i % num1 == 0 and i % num2 == 0 , and thus never sets a value for the lcm. Also notice that the second part of the code must be outside the if/else .

def compute_lcm(num1, num2):
    if num1 > num2:
        greater = num1
    else:
        greater = num2

    lcm = None
    for i in range(1, greater + 1):
        if i % num1 == 0 and i % num2 == 0:
            lcm = i
    print(lcm)


compute_lcm(12, 14)  # >>> None