I just started learning Python and I've just been messing around typing different codes for practice to learn, and I made this code:
import math
def lol():
print (math.cos(math.pi))
print ("I hope this works")
def print_twice(bruce):
print bruce
print bruce
print_twice(lol())
When I run it, my output is:
-1.0
I hope this works
None
None
How come it isn't printing the function lol() twice?
Your code print_twice(lol()) is saying to execute lol() and pass it's return value into print_twice(). Since you didn't specify a return value for lol(), it returns None. So, lol() is printed once when it gets executed, and both print statements in print_twice() print passed value of None.
This is what you want:
def lol():
print (math.cos(math.pi))
print ("I hope this works")
def print_twice(bruce):
bruce()
bruce()
print_twice(lol)
Instead of passing the return value of lol(), we are now passing the function lol, which we then execute twice in print_twice().
You should note that printing is different from returning.
When you call print_twice(lol()) it will first call lol() which will print -1.0 and I hope this works and will return None, then it will continue calling print_twice(None) which will call print None twice.
print_twice('foo'), you only need to make sure that its argument is a string, in that case you could change lol so it returns something. def lol: return 'foo' then print_twice(lol()) would print 'foo' twice.How you might run as expected:
def lol():
print "lol"
def run_twice(func):
func()
func()
run_twice(lol)
