计数器变量为类

Question

我有问题得到这段代码运行。这个班级是具有IdCounter的学生，这是问题出现的地方。 （在8号线）

class Student: 
    idCounter = 0 
    def __init__(self): 
     self.gpa = 0 
     self.record = {} 
     # Each time I create a new student, the idCounter increment 
     idCounter += 1 
     self.name = 'Student {0}'.format(Student.idCounter) 

classRoster = [] # List of students 
for number in range(25): 
    newStudent = Student() 
    classRoster.append(newStudent) 
    print(newStudent.name) 

我想有我Student类这里面idCounter，这样我就可以把它作为学生的名字（这是一个真正的编号，例如Student 12345的一部分。但我有已经越来越错误。

Traceback (most recent call last): 
    File "/Users/yanwchan/Documents/test.py", line 13, in <module> 
    newStudent = Student() 
    File "/Users/yanwchan/Documents/test.py", line 8, in __init__ 
    idCounter += 1 
UnboundLocalError: local variable 'idCounter' referenced before assignment 

我试图把idCounter + = 1之前，之后，所有的组合，但我仍然得到referenced before assignment错误，你能向我解释什么，我做错了什么？

Answer 1

class Student: 
    # A student ID counter 
    idCounter = 0 
    def __init__(self): 
     self.gpa = 0 
     self.record = {} 
     # Each time I create a new student, the idCounter increment 
     Student.idCounter += 1 
     self.name = 'Student {0}'.format(Student.idCounter) 

classRoster = [] # List of students 
for number in range(25): 
    newStudent = Student() 
    classRoster.append(newStudent) 
    print(newStudent.name) 

感谢Ignacio，Vazquez-Abrams指出的点点滴滴......