语法错误：“无法分配给运算符” Python

Question

a, b, c = 0, 1,0
while c < 1000000:
    print (b)
    a, b = b, a + b, c = c + b

The interpreter throws me the "can't assign to operator" error. Ninja IDE highlights the variable initialisation to be the problem. However when I run the code in the interpreter, the "a + b" is highlighted as the problem part. Can you help me identify the issue i'm having?

Answer 1

when you write a, b, c = 0, 1, 0 , you are not creating multiple assignments. Instead, you implicitly use tuple packing and unpacking . In the line a, b = b, a + b, c = c + b , you are trying to do the same but the right part of the assignment contains another assignment, which is invalid (in python an assignment is not an expression). If you want to write it in one line, you should write

a, b, c = b, a + b, a + b + c

However, since the value of c relies on the value of b having changed, it is probably clearer to split it into two lines

a, b = b, a + b
c = c + b

Answer 2

Similar to how a, b, c = 0, 1,0 works...

This line is trying to assign a and b to the right hand side of the equals. You've got three things over there, and one of those is a variable assignment operation

a, b = b, a + b, c = c + b

Maybe you meant this instead

a, b,c = b, a + b, c + b

Or, of course, just do it on multiple lines

Answer 3

Its a simple fix: change where the c = c + b is in your code.

a, b, c = 0, 1,0
while c < 1000000:
    print (b)
    a, b, c = b, a + b, c + b

What it's doing is:

a = b
b = a+b
c = c+b

But you can write it in separate lines.

Hope that helps

Answer 4

The variables BEFORE the "=" sign will be interpreted as the variable that you are going to store on. The data AFTER the "=" sign will be interpreted as the data that you are going to store in the variable you just created in the left side with respect to the same position.

Example:

a,b = 5,10
print(a)
#Outputs 5
print(b)
#Outputs 10

Since you only have two variables before the "=" sign, there will be only two container for the data you just type after the "=" sign which is b and a+b