02-First test

02-First test

 1.Type 'python' in command line, we can open the python interaction console

    symbol >>>

    	test:

		    >>> 100+100
			200
			>>> 6000*2
			12000
			>>> print(5)
			5
			>>> prin("hello")
			Traceback (most recent call last):
			  File "<stdin>", line 1, in <module>
			NameError: name 'prin' is not defined
			>>> print("hello")
			hello
			>>> print('hello')
			hello
			>>> print('5'+"1000")
			51000
			>>> exit()

	Under this circumstance, we can't save anything.

2. create a new file, text "print("hello world")", save as .py
	go to the direction in console and run it 

	1) use 'python' as the key word to run

	SuzydeMacBook-Pro:python suzy$ python hello.py
	hello world

	2) add '#!/usr/bin/env python3' on top of the file

	run   chmod a+x 02-hello.py
	then we can run hello.py directly without keyword python

	test:

 		SuzydeMacBook-Pro:python suzy$ chmod a+x hello.py
		SuzydeMacBook-Pro:python suzy$ ./hello.py
		hello world
		SuzydeMacBook-Pro:python suzy$ ./hello.py
		hello world!!!