Python version is 2.7.13
System is window7
Global Variables and Local Variables
Now We often meet the Error which is UnboundlocalError.It’s a frequent question in the learning python.So I try to research the issue today to kown how the variables work in the function and class.
- The function defaults that the variable is a global variable
i=8
def t():
print i
t()
8
The 'i’s value is 8 which is comfire the result.
- If the Global variable is not named in the function,it would report error
UnboundLocalError: local variable 'i' referenced before assignment
i=4
def t():
i+=1
print i
t()
- You could name the variable use in keyword
global.
i=4
def t():
global i
i+=1
print i
t()
5
i
5
The global variable i is change too.
- If you don’t want to change the global variable,you could assign it to another local variable.
i=4
def t():
global i
t=i
t+=1
print t
t()
5
i
4
- You can also reference global variables on function arguments
i=4
def t(i):
print i
i=2
print t
t()
4
2