Practical Coding in Python

#
# loops.py
#


# Lists are declared with the square brackets, and may contain
# objects with different types.

things = [7, 4.20, "juggling ball", True]
print("things:", things)

# List indexing is 0-based, just like Java.

print("things[0]:", things[0])
print("things[2]:", things[2])

# You can also give index ranges, resulting in a "slice" of the
# list, and negative indices which count from the end.

print("things[0:2]", things[0:2])
print("things[-1]:", things[-1])
print("things[-2]:", things[-2])

# The Python for loop to iterate through a list is similar to the
# Java for-each loop.

# Important difference from Java: Python uses the colon followed by
# indented code to indicate scope, where Java uses the curly braces
# {}.  You can indent any amount, but you must be consistent within
# the scope.

print("printing items")
for item in things:
    print("item:", item)

# You can also use the range() function to iterate through a range
# of integers.  range(begin, end) returns the integers in the
# half-open interval [begin,end). range(end) is shorthand for
# range(0, end).  You can also specify a step parameter:
# range(begin, end, step).

print("printing range(5)")
for x in range(5):
    print("x:", x)

print("printing range(11, 20, 2)")
for x in range(11, 20, 2):
    print("x:", x)


# Conditions are checked with `if`, with scope specified by
# indentation as with `for`.

# Note that = and == are the similar to Java:
#   =  is assignment
#   == is comparison (returns a boolean)

# However, Python is different from Java in that == compares
# values, not references.

print("printing with conditions")
for i in range(10):
    if i%2 == 0:
        print("Even")
    elif i == 7:                # "else if" in Java
        print("Lucky")
    else:
        print(i)