Basic Python3

$ python3
Python 3.6.3 (default, Oct  3 2017, 21:45:48)
[GCC 7.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> print("hello world")
hello world
>>>

string = "string"
dir(string)
help(string.count)

# comment

x = 1
if x == 1:
    # indented four spaces
    print("x is 1.")

# Immutable
myval = "python"
id(myval)

myval = "love python"
id(myval)

# Mutable
mylist = []
id(mylist)

mylist.append("hello")
id(mylist)

myint = 7
print(myint)

myfloat = 7.0
print(myfloat)
myfloat = float(7)
print(myfloat)

mystring = 'hello'
print(mystring)
mystring = "hello"
print(mystring)

one = 1
two = 2
three = one + two
print(three)

hello = "hello"
world = "world"
helloworld = hello + " " + world
print(helloworld)

a, b = 3, 4
print(a,b)

# change this code
mystring = None
myfloat = None
myint = None

# testing code
if mystring == "hello":
    print("String: %s" % mystring)
if isinstance(myfloat, float) and myfloat == 10.0:
    print("Float: %f" % myfloat)
if isinstance(myint, int) and myint == 20:
    print("Integer: %d" % myint)

mylist = []
mylist.append(1)
mylist.append(2)
mylist.append(3)
print(mylist[0]) # prints 1
print(mylist[1]) # prints 2
print(mylist[2]) # prints 3

# prints out 1,2,3
for x in mylist:
    print(x)

mylist = [1,2,3]
print(mylist[10])
print(len(mylist))

numbers = []
strings = []
names = ["John", "Eric", "Jessica"]

# add numbers, strings

second_name = names[1]
print(numbers)
print(strings)
print("The second name on the names list is %s" % second_name)

number = 1 + 2 * 3 / 4.0
print(number)

remainder = 11 % 3
print(remainder)

squared = 7 ** 2
cubed = 2 ** 3

print(squared)
print(cubed)

helloworld = "hello" + " " + "world"
print(helloworld)

lotsofhellos = "hello" * 10
print(lotsofhellos)

even_numbers = [2,4,6,8]
odd_numbers = [1,3,5,7]
all_numbers = odd_numbers + even_numbers
print(all_numbers)

print([1,2,3] * 3)

x = object()
y = object()

x_list = [x]
y_list = [y]
big_list = []

print("x_list contains %d objects" % len(x_list))
print("y_list contains %d objects" % len(y_list))
print("big_list contains %d objects" % len(big_list))

# testing code
if x_list.count(x) == 10 and y_list.count(y) == 10:
    print("Almost there...")
if big_list.count(x) == 10 and big_list.count(y) == 10:
    print("Great!")

# This prints out "Hello, John!"
name = "John"
print("Hello, %s!" % name)

# This prints out "John is 23 years old."
name = "John"
age = 23
print("%s is %d years old." % (name, age))

# This prints out: A list: [1, 2, 3]
mylist = [1,2,3]
print("A list: %s" % mylist)

data = ("John", "Doe", 53.44)
format_string = "Hello %s %s. Your current balance is $%s."

print(format_string % data)

"Hello {0}, {1}".format("Guido van", "Rossum")

"Hello {firstname}, {lastname}".format(firstname="Guido van", name="Rossum")

astring = "Hello world!"
astring2 = 'Hello world!'

astring = "Hello world!"
print("single quotes are ' '")

print(len(astring))

astring = "Hello world!"
print(astring.index("o"))

astring = "Hello world!"
print(astring.count("l"))

H   e   l   l   o       W   o   r   l   d
0   1   2   3   4   5   6   7   8   9   10
-11 -10 -9  -8  -7  -6  -5  -4  -3  -2  -1

astring = "Hello world!"
print(astring[3:7])

astring = "Hello world!"
print(astring[3:7:2])

number = [13, 14, 15, 16, 17, 18, 19]
print(number[::2])

name = "Monty Python"
print(name[0:2])
print(name[2:5])
print(name[:4])
print(name[4:])
print(name[:])
print(name[1:-1])

astring = "Hello world!"
print(astring.upper())
print(astring.lower())

astring = "Hello world!"
print(astring.startswith("Hello"))
print(astring.endswith("asdfasdfasdf"))

astring = "Hello world!"
afewwords = astring.split(" ")

x = 2
print(x == 2)
print(x == 3)
print(x < 3)

name = "John"
age = 23
if name == "John" and age == 23:
    print("Your name is John, and you are also 23 years old.")

if name == "John" or name == "Rick":
    print("Your name is either John or Rick.")

name = "John"
if name in ["John", "Rick"]:
    print("Your name is either John or Rick.")

x = 2
if x == 2:
    print("x equals two!")
else:
    print("x does not equal to two.")

x = [1,2,3]
y = [1,2,3]
print(x == y) # Prints out True
print(x is y) # Prints out False

a = 2
b = 2
print(a is b)

print(not False)
print((not False) == (False))

primes = [2, 3, 5, 7]
for prime in primes:
    print(prime)

# Prints out the numbers 0,1,2,3,4
for x in range(5):
    print(x)

# Prints out 3,4,5
for x in range(3, 6):
    print(x)

# Prints out 3,5,7
for x in range(3, 8, 2):
    print(x)

count = 0
while count < 5:
    print(count)
    count += 1  # This is the same as count = count + 1

# Prints out 0,1,2,3,4

count = 0
while True:
    print(count)
    count += 1
    if count >= 5:
        break

# Prints out only odd numbers - 1,3,5,7,9
for x in range(10):
    # Check if x is even
    if x % 2 == 0:
        continue
    print(x)

count=0
while(count<5):
    print(count)
    count +=1
else:
    print("count value reached %d" %(count))

# Prints out 1,2,3,4
for i in range(1, 10):
    if(i%5==0):
        break
    print(i)
else:
    print("this is not printed because for loop is terminated because of break but not due to fail in condition")

def my_function():
    print("Hello From My Function!")

def my_function_with_args(username, greeting):
    print("Hello, %s , From My Function!, I wish you %s"%(username, greeting))

def sum_two_numbers(a, b):
    return a + b

my_function()
my_function_with_args("John Doe", "a great year!")
x = sum_two_numbers(1,2)

class MyClass:
    variable = "blah"

    def function(self):
        print("This is a message inside the class.")

myobjectx = MyClass()
myobjecty = MyClass()

print(myobjectx.variable)
print(myobjecty.variable)

myobjectx.function()
myobjecty.function()

phonebook = {}
phonebook["John"] = 938477566
phonebook["Jack"] = 938377264
phonebook["Jill"] = 947662781
print(phonebook)

phonebook = {"John" : 938477566,"Jack" : 938377264,"Jill" : 947662781}
for name, number in phonebook.items():
    print("Phone number of %s is %d" % (name, number))

del phonebook["John"]
print(phonebook)

phonebook = {
   "John" : 938477566,
   "Jack" : 938377264,
   "Jill" : 947662781
}
phonebook.pop("John")
print(phonebook)

if "Jake" in phonebook:
    print("Jake is listed in the phonebook.")
if "Jill" not in phonebook:
    print("Jill is not listed in the phonebook.")

tup1 = ('physics', 'chemistry', 1997, 2000);
tup2 = (1, 2, 3, 4, 5 );
tup3 = "a", "b", "c", "d";

tup1 = ();

tup1 = (50,);

tup1 = ('physics', 'chemistry', 1997, 2000);
tup2 = (1, 2, 3, 4, 5, 6, 7 );
print "tup1[0]: ", tup1[0];
print "tup2[1:5]: ", tup2[1:5];

tup1 = (12, 34.56);
tup2 = ('abc', 'xyz');

# Following action is not valid for tuples
# tup1[0] = 100;

# So let's create a new tuple as follows
tup3 = tup1 + tup2;
print tup3;

tup = ('physics', 'chemistry', 1997, 2000);
print tup;
del tup;
print("After deleting tup : ");
print tup;

import urllib
dir(urllib)
help(urllib.urlopen)

def changeme( mylist ):
   "This changes a passed list into this function"
   mylist.append([1,2,3,4]);
   print "Values inside the function: ", mylist
   return

# Now you can call changeme function
mylist = [10,20,30];
changeme( mylist );
print "Values outside the function: ", mylist

def changeme( mylist ):
   "This changes a passed list into this function"
   mylist = [1,2,3,4]; # This would assig new reference in mylist
   print "Values inside the function: ", mylist
   return

# Now you can call changeme function
mylist = [10,20,30];
changeme( mylist );
print "Values outside the function: ", mylist

def printme( str ):
   "This prints a passed string into this function"
   print(str)
   return;

# Now you can call printme function
printme()

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: printme() missing 1 required positional argument: 'str'

def printinfo( name, age ):
   "This prints a passed info into this function"
   print("Name: ", name)
   print("Age ", age)
   return

printinfo("miki",50)
printinfo( age=50, name="miki" )
printinfo(50,"Abc")

def printinfo( arg1, *vartuple ):
   "This prints a variable passed arguments"
   print("Output is: ")
   print(arg1)
   for var in vartuple:
      print(var)
   return;

# Now you can call printinfo function
printinfo( 10 )
printinfo( 70, 60, 50 )

def printinfo( arg1, **vardic ):
   "This prints a variable passed arguments"
   print("Output is: ")
   print(arg1)
   for key,var in vardic.items():
      print("key {} , var {}".format(key,var))
   return;

# Now you can call printinfo function
printinfo( 10 )
printinfo( 70, x=60, y=50 )

def example(arg1,arg2, *args, **kwargs):
    print(arg1)
    print(arg2)
    print(args)
    for key,var in kwargs.items():
       print("key {} , var {}".format(key,var))
    return;

example(1,2,3,4,x=1,y=2)

## Run python File
สร้าง file main.py

run

ตัวอย่าง
file: area.py

file: call_area.py

run

- สรุปได้ว่า เมื่อมีการเรียกการใช้งาน module โดยตรง __name__ จะมีค่า  __main__
- แต่หากมีการเรียกการใช้งานในลักษณะ import จะทำให้ค่าของ __name__ จะเป็นชื่อของ module

โดย default นั้น ค่าของ ``__name__`` จะมีค่าเป็น __main__