语法错误：无效的令牌 python 3

Question

I have a problem with my Python script. When I run this Python script :

class Student:
    def __init__(self,student_name,student_id,student_phone):
        self.student_name = student_name
        self.student_id = student_id
        self.student_phone = student_phone

obj = Student("ELizaa",1253251,16165544)

print("student name",obj.student_name,"\nstudent id",obj.student_id,"\nStudent phone",obj.student_phone)

It is working fine. I got the expected output. But when student_phone starting with a 0 (like 0124575 ), I get an error :

obj = Student("ELizaa",1253251,016165544)
                                         ^
SyntaxError: invalid token

Why is this happening?

Answer 1

In python3, you couldn't use 016165544 to create an integer variable. It's an octonary number in some other programming language, such as C . In Python, you should use 0o16165544 or 0O16165544 .

However, what you want to create is a student ID and phone number, so I suggest that you use string instead.

Like this:

obj = Student("ELizaa", "1253251", "016165544")

Answer 2

In Python, adding 0 in front of any number needs an extra

• x (for hexadecimal) followed by any number in hex digits range 0-9 or af or AF .

• o (for octal) followed by number(s) in octal digits range 0-7 .

Have a look at below:

>>> 0o7
7
>>> 0o71
57
>>> 0o713
459
>>>
>>> 0xa
10
>>> 0xA
10
>>> 0x67
103
>>> 

» If you exceed the range or if you don't use x | o after 0 .

>>> 0o8
  File "<stdin>", line 1
    0o8
     ^
SyntaxError: invalid token
>>> 
>>> 08
  File "<stdin>", line 1
    08
     ^
SyntaxError: invalid token
>>> 

Suggestion: If you are still willing to use 0 & want to perform operations on phones (for testing) then you can use the below approach to update the numbers.

Here we will store phone number as string & whenever we will update that, we will remove 0 from front, convert the remaining part into an integer, add (any operation) ant convert back to its original ( 0 in front) form & I think it is good.

>>> student_phone = "016165544"
>>> 
>>> # Add 3 to this
... 
>>> student_phone = "0" + str(int(student_phone.lstrip("0")) + 3)
>>> 
>>> student_phone
'016165547'
>>>  

Finally, you can call in this way (as you are already doing in your problem except 2nd one).

>>> class Student:
...     def __init__(self, student_name, student_id, student_phone):
...         self.student_name = student_name
...         self.student_id = student_id
...         self.student_phone = student_phone
... 
>>> obj = Student("ELizaa",1253251,16165544)
>>> print("student name",obj.student_name,"\nstudent id",obj.student_id,"\nStudent phone",obj.student_phone)
student name ELizaa 
student id 1253251 
Student phone 16165544
>>> 
>>> obj = Student("ELizaa",1253251,"016165544")                                
>>> print("student name",obj.student_name,"\nstudent id",obj.student_id,"\nStudent phone",obj.student_phone)
student name ELizaa 
student id 1253251 
Student phone 016165544
>>> 

Answer 3

Starting a number with the digit 0 makes it an octal number, but the behavior has some nuance. See this solution: Invalid Token when using Octal numbers