Learning Python

11. Conditions

Python supports the usual logical conditions from mathematics:

  • Equals: a == b
  • Not Equals: a != b
  • Less than: a < b
  • Less than or equal to: a <= b
  • Greater than: a > b
  • Greater than or equal to: a >= b
a = 33
b = 200
if b > a:
  print("b is greater than a")

Indentation

a = 33
b = 200
if b > a:
print("b is greater than a") # you will get an error

11.1. if-then-elif

a = 33
b = 33
if b > a:
  print("b is greater than a")
elif a == b:
  print("a and b are equal")

11.2. if-then-else

a = 200
b = 33
if b > a:
  print("b is greater than a")
else:
  print("b is not greater than a")
a = 200
b = 33
if b > a:
  print("b is greater than a")
elif a == b:
  print("a and b are equal")
else:
  print("a is greater than b")

11.3. Nested if-then-else

x = 41

if x > 10:
  print("Above ten,")
  if x > 20:
    print("and also above 20!")
  else:
    print("but not above 20.")

11.4. Logical operators

And

a = 200
b = 33
c = 500
if a > b and c > a:
  print("Both conditions are True")

Or

a = 200
b = 33
c = 500
if a > b or a > c:
  print("At least one of the conditions is True")

11.5. Shorthand and Conditional Expressions

a = 2
b = 330
if a > b: print("a is greater than b")
a = 2
b = 330
print("A") if a > b else print("B")

Ternary Conditional Operator

a = 2
b = 330
print("A") if a > b else print("B")
b = 330
print("A") if a > b else print("=") if a == b else print("B")