Learning Python

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

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")

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")

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.")

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")

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")

Using Functions

def my_function():
    print("Hello from a function")
def my_function():
    print("Hello from a function")


def main():
    my_function()
def my_function(fname):
    print(fname + " Refsnes")


def main():
    my_function("Emil")
    my_function("Tobias")
    my_function("Linus")
def my_function(x):
    return 5 * x


def main():
    print(my_function(3))
    print(my_function(5))
    print(my_function(9))
def my_function(country = "Norway"):
    print("I am from " + country)


def main():
    my_function("Sweden")
    my_function("India")
    my_function()
    my_function("Brazil")