Ветвления

2.4.1.py

# -*- encoding: utf-8 -*-
"""
Базовый синтаксис
"""

x = int(raw_input("Please enter an integer: "))
if x < 0:
      x = 0
      print 'Negative changed to zero'
elif x == 0:
      print 'Zero'
elif x == 1:
      print 'Single'
else:
      print 'More'

2.4.2.py

# -*- encoding: utf-8 -*-
"""
Составное условие
"""

number = 1
if number <= 10 and number >= 1:
    print 'Great!'
else:
    print 'Wrong!'

2.4.3.py

# -*- encoding: utf-8 -*-
"""
Стандартный селектор
"""

choice = 'ham'
print {'spam':  1.25,         # a dictionary-based 'switch'
       'ham':   1.99,         # use has_key() or get() for default
       'eggs':  0.99,
        'bacon': 1.10}[choice]

if choice == 'spam':
     print 1.25
elif choice == 'ham':
     print 1.99
elif choice == 'eggs':
     print 0.99
elif choice == 'bacon':
     print 1.10
else:
     print 'Bad choice'

2.4.4.py

# -*- encoding: utf-8 -*-
"""
Вложеные условия
"""

x = 1

if x:
    y = 2
    if y:
        print 'block2'
    print 'block1'