<a href="http://www.jianshu.com/p/54870e9541fc">总目录</a>
课程页面:https://www.codecademy.com/
内容包含课程笔记和自己的扩展折腾
Comparators
==
!=
<
<=
>
>=
Boolean operators
- and
- true and true: true
- true and false: false
- false and false: false
- or
- true or true: true
- true or false: true
- false or false: false
- not
- not true: false
- not false: true
- 如果不加括号,计算机处理就有顺序(类似orders of operations里面的pemdas),即是n->a->o.
Conditional Statement Syntax (if)
- 如果if后面的expression是True,就执行if后面的命令
if 6 + 1 != 10:
print "abc"
- 如果if后面的fuction return的是True, 就执行if后面的命令
def addition():
if 1 + 1 == 2:
return True
#
def print_result():
if addition():
return "2"
#
print "1+1=" + print_result()
if ... else ...
- 对if进行补充。
def addition(a, b):
if a >= b:
print "the 1st number %s is NOT less than the 2nd number %s" % (a, b)
else:
print "the 1st number %s is less than the 2nd number %s" % (a, b)
#
addition(3, 3)
addition(1, 6)
addition(6, 1)
"""
Output:
the 1st number 3 is NOT less than the 2nd number 3
the 1st number 1 is less than the 2nd number 6
the 1st number 6 is NOT less than the 2nd number 1
"""
if... elif... elif... else...
- elif满足多个if的要求。按顺序执行。
def addition(a, b):
if a > b:
print "the 1st number %s is greater than the 2nd number %s" % (a, b)
elif a == b:
print "the 1st number %s is equal to the 2nd number %s" % (a, b)
else:
print "the 1st number %s is less than the 2nd number %s" % (a, b)
#
addition(3, 3)
addition(1, 6)
addition(6, 1)
"""
Output:
the 1st number 3 is equal to the 2nd number 3
the 1st number 1 is less than the 2nd number 6
the 1st number 6 is greater than the 2nd number 1
"""