Python: The use of relation operators

Abstract: Kills how to use relation operators

1. The use of plus operator “+”

The common use is for plus.

>>> a=1

>>> b=4

>>> print a+b

5

Combine multiple strings into a string

>>> c='da'

>>> print a+c

Traceback (most recent call last):

File "<stdin>", line 1, in <module>

TypeError: unsupported operand type(s) for +: 'int' and 'str'

>>> print str(a)+c

1da

>>> d='32a'

>>> print c+d

da32a

Combine multiple lists

>>> a=range(10)

>>> b=range(10,20)

>>> print a

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

>>> print b

[10, 11, 12, 13, 14, 15, 16, 17, 18, 19]

>>> print a+b

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]

2. Boolean expression

Here is a common statements for Python or some other programming language.

>>> a=10

>>> if a>0 and a<100:

... print a

...

10

You can write it with a simple pattern:

>>> if 0< a<100:

... print a

...

10

writing date: 20150522