Using the AND and NOT Operator in Python

Here is my custom class that I have that represents a triangle. I'm trying to write code that checks to see if self.a, self.b, and self.c are greater than 0, which would mean that I have Angle, Angle, Angle.

Below you will see the code that checks for A and B, however when I use just self.a != 0 then it works fine. I believe I'm not using & correctly. Any ideas? Here is how I am calling it: print myTri.detType()

class Triangle:

	# Angle A To Angle C Connects Side F
	# Angle C to Angle B Connects Side D
	# Angle B to Angle A Connects Side E

	def __init__(self, a, b, c, d, e, f):
		self.a = a
		self.b = b
		self.c = c
		self.d = d
		self.e = e
		self.f = f
		
	def detType(self):
		#Triangle Type AAA
		if self.a != 0 & self.b != 0:
			return self.a
		
		#If self.a > 10:
			#return AAA
		
		#Triangle Type AAS
		
		#elif self.a = 0:
			#return AAS
		
		#Triangle Type ASA
		
		#Triangle Type SAS
		
		#Triangle Type SSS	
		
		#else:
			#return unknown

You should write :

if (self.a != 0) and (self.b != 0) :

"&" is the bit wise operator and does not suit for boolean operations. The equivalent of "&&" is "and" in Python.

A shorter way to check what you want is to use the "in" operator :

if 0 not in (self.a, self.b) :

You can check if anything is part of a an iterable with "in", it works for :

• Tuples. I.E : "foo" in ("foo", 1, c, etc) will return true
• Lists. I.E : "foo" in ["foo", 1, c, etc] will return true
• Strings. I.E : "a" in "ago" will return true
• Dict. I.E : "foo" in {"foo" : "bar"} will return true

As an answer to the comments :

Yes, using "in" is slower since you are creating an Tuple object, but really performances are not an issue here, plus readability matters a lot in Python.

For the triangle check, it's easier to read :

0 not in (self.a, self.b, self.c)

Than

(self.a != 0) and (self.b != 0) and (self.c != 0) 

It's easier to refactor too.

Of course, in this example, it really is not that important, it's very simple snippet. But this style leads to a Pythonic code, which leads to a happier programmer (and losing weight, improving sex life, etc.) on big programs.

Use the keyword and, not & because & is a bit operator.

Be careful with this... just so you know, in Java and C++, the & operator is ALSO a bit operator. The correct way to do a boolean comparison in those languages is &&. Similarly | is a bit operator, and || is a boolean operator. In Python and and or are used for boolean comparisons.

It's called and and or in Python.