If Statement

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

if <expression>:
    Statements

Indentation

Python relies on indentation (whitespace at the beginning of a line) to define scope in the code. Other programming languages often use curly-brackets for this purpose

# wrong indentation 
if <expression>:
Statements

Elif

The elif keyword is pythons way of saying "if the previous conditions were not true, then try this condition".

if <expression>:
    Statements
elif <expression>:
    Statements

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

Else

The else keyword catches anything which isn't caught by the preceding conditions.

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")
Output: a is greater than b

You can also have an else without the elif:

Short Hand If

if a > b: print("a is greater than b")

Short Hand If ... Else

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

logical operators

And

The and keyword is a logical operator, and is used to combine conditional statements:

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")

Nested If

x = 41

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

The pass Statement

if statements cannot be empty, but if you for some reason have an if statement with no content, put in the pass statement to avoid getting an error.

a = 33
b = 200

if b > a:
  pass

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