Python global variable

python variables global-variables global
Don Lun picture Don Lun · Apr 4, 2011 · Viewed 34.1k times · Source 
def say_boo_twice():
  global boo
  boo = 'Boo!'
  print boo, boo

boo = 'boo boo'
say_boo_twice()

The output is

Boo! Boo!

Not as I expected. Since I declared boo as global, why is the output not:

boo boo boo boo

Answer

Dr McKay picture Dr McKay · Apr 4, 2011

You've changed boo inside your function, why wouldn't it change? Also, global variables are bad.

Related questions

Correct Use Of Global Variables In Python 3

Which is the correct use of global variables in Python 3?: 1) Stating global VAR_NAME once in the core script (not within a function) and then simply referring to the variable as VAR_NAME everywhere else 2) Stating global VAR_NAME once …

Read More
How can I print variable and string on same line in Python?

I am using python to work out how many children would be born in 5 years if a child was born every 7 seconds. The problem is on my last line. How do I get a variable to work when I'm printing …

Read More
How do I check if a variable exists?

I want to check if a variable exists. Now I'm doing something like this: try: myVar except NameError: # Do something. Are there other ways without exceptions?

Read More