Keyword | Description | Code example |
False, True | Data values from the data type Boolean | False == (1 > 2), True == (2 > 1) |
and, or, not | Logical operators: (x and y) → both x and y must beTrue (x or y) → either x or y must be True (not x) → x must be false | x, y = True, False (x or y) == True # True (x and y) == False # True (not y) == True # True |
break | Ends loop prematurely | while(True): break # no infinite loop print("hello world") |
continue | Finishes current loop iteration | while(True): continue print("43") # dead code |
class def | Defines a new class → a real-world concept (object oriented programming) Defines a new function or class method. For latter, first parameter (“self”) points to the class object. When calling class method, first parameter is implicit. | class Beer: def __init__(self): self.content = 1.0 def drink(self): self.content = 0.0 becks = Beer() # constructor - create class becks.drink() # beer empty: b.content == 0 |
if, elif, else | Conditional program execution: program starts with“if” branch, tries the “elif” branches, and finishes with “else” branch (until one branch evaluates to True). | x = int(input("your value: ")) if x > 3: print("Big") elif x == 3: print("Medium") else: print("Small") |
for, while | # For loop declaration for i in [0,1,2]: print(i) | # While loop - same semantics j = 0 while j < 3: print(j) j = j + 1 |
in | Checks whether element is in sequence | 42 in [2, 39, 42] # True |
is | Checks whether both elements point to the same object | y = x = 3 x is y # True [3] is [3] # False |
None | Empty value constant | def f(): x = 2 f() is None # True |
lambda] return | Function with no name (anonymous function) Terminates execution of the function and passes the flow of execution to the caller. An optional value after the return keyword specifies the function result. | (lambda x: x + 3)(3) # returns 6 def incrementor(x): return x + 1 incrementor(4) # returns 5 |
