Python基础

1.提示用户输入

input('Enter an integer:')

2.条件判断语句

    number = 23
    guess = int(input('Enter an integer'))
    if guess == number:
        print('ok')
        print('o,year')
    elif guess > number:
        print('guess>number')
    else:
        print('guess<nuber')

 3.for循环

for i in range(1,5,2):
        print(i)
    else:
        print('else');

 4.while循环

    run = True
    while(run):
        print('loop')
        run = False
    else:
        print("else")

 5.break
while及for循环的else子句也不会被执行

    while True:
        str = input('Enter:')
        if str == 'quit':
            break
        print('str length is ', len(str))

 
6.continue:跳过当前循环的剩余语句

    while True:
        str = input('Enter:')
        if str == 'quit':
            break
        if len(str) < 3:
            continue
        print('str length is ok')

 7.定义方法
必须放在被调用代码之前

def sayHello():
    print('Hello World')

 
8.在方法内修改方法外的变量，可在方法内用global先声明该变量

def sayHello(i):
    global x
    print('Hello World',x)
    x = 10
    print('Hello World',x)

x=20
sayHello(3)
print('thie value is',x)

 
9.为形参设默认值

def showMsg(msg, time = 1):
    print(msg * time)

showMsg('hello')
showMsg('hello', 6)

 

10.关键参数

def testParam(a, b = 1, c = 2):
    print('a is',a,'and b is', b, 'and c is', c)

testParam(10)
testParam(a=1,c=20)
testParam(c=30, b=20, a=10)

 

11.return
如何没有return语句，默认暗含return Null

12.DocStrings

def testParam(a, b = 1, c = 2):
    "ddddddddddddddddd"
    print('a is',a,'and b is', b, 'and c is', c)

print(testParam.__doc__)

 

13.使用模块

import sys

for i in sys.argv:
    print(i)

print(sys.path)

 

14.del用来删除变量

a = 2
print(a)
del(a)
#print(a)

 

15.List的使用

fruitList = ['apple', 'barana', 'tao']
print(len(fruitList))
for item in fruitList:
    print(item)

fruitList.append('li')
fruitList.sort()
for item in fruitList:
    print(item)
item0 = fruitList[0]
del fruitList[0]
print(fruitList)
printfruitList [1:])

 

16.元组的使用

num=('one', 'two', 'three')
print(len(num))
print(num)
newNum=('1','2',num)
print(len(num))
print(newNum[2][2])
secNum=(1,)
print(len(secNum))

 

17. 字典

num={1:'one',2:'two',3:'three',4:'four',5:'five'}
print(num[1])
num[6]='six'
print(num)
del num[1]
for key,value in num.items():
    print(key,":" + value)
if 4 in num:
    print('yes')

 

18.类

class Person:
    age = 0
    def __init__(self, name):
        self.name = name
        Person.age += 1
    def say(self):
        print('my name is', self.name)
        if Person.age == 0:
            print('my age is 0')
        elif Person.age == 1:
            print('my age is 1')
        else:
            print('else')

p=Person("peng")
p.say()