1.输入及占位符练习
从命令行输入两个数字，打印两个数字的和及平均数。
#!/usr/bin/env python
# coding: utf8
num1 = raw_input("Please input num1: ")
num2 = raw_input("Please input num2: ")
sum = int(num1) + int(num2)
print '%s + %s = %s' % (num1, num2, sum)
print '(%s + %s) / 2 = %s' % (num1, num2, sum * 1.0 / 2)
>>>
Please input num1: 1
Please input num2: 2
1 + 2 = 3
(1 + 2) / 2 = 1.51. 逻辑运算
布尔运算：True / False
None 0 "" [] () {} ==> False
>>> 1 < 2 True >>> 1 != 2 True >>> 1 == 2 False >>> a = 2 >>> b = 1 >>> a != b True >>> a <= b False
逻辑或/且,或(or),且（and）
或： a or b a = True, b = True a = True, b = False a = False, b = True a = False, b = False a or b:如果a或者b之间有一个为True，则结果为True 真值表: (a or b) a(True) a(False) b(True) True True b(False) True False a or b or c or .... or z (((a or b) or c) or ....) or z >>> True or True True >>> True or False True >>> False or True True >>> False or False False >>> True or False or True True >>> False or True or False True ======================================= 且: a and b a和b同时都为True,结果为True 真值表: (a and b) a(True) a(False) b(True) True False b(False) False False >>> True and True True >>> True and False False >>> False and True False >>> False and False False
用法：逻辑判断
if True/False:
为真（True）则执行语句
语句1
语句2
...
2. if 支持嵌套
if 1 == 1:
if 2 == 2:
print("满足2=2条件，输出结果")
else:
print('不满足2=2条件，输出结果')
else:
print("不满足1==1条件，输出结果")
3. if elif
inp = input('请输入级别：')
if inp == "白银":
print('玩个锤子')
elif inp == "黄金":
print('可以一战')
elif inp == "钻石":
print('还不错哦！')
elif inp == "王者":
print('大神别走，带带我！')
else:
print('滚')
print('老司机快上车...')
补充：pass
if 1==1:
pass #不管拉不拉屎，先占住坑
else:
print('一边凉快去')2.if else练习
输入一个分数score
如果成绩在[0, 60) 打印不及格
[60, 70) 一般
[70, 80) 良好
[80, 90) 优良
[90, 100] 优秀
score <0 或者 > 100, print 你输入错误
>>>
score = raw_input("Please input your score: ")
score = int(score)
if score < 0:
print '你输入错误'
elif score < 60:
print '不及格'
elif score < 70:
print '一般'
elif score < 80:
print '良好'
elif score < 90:
print '优良'
elif score <= 100:
print '优秀'
else:
print '你输入错误'
逻辑非：not A
A True, not A => False A False, not A => True
2. while循环
while 判断条件： #如果判断条件是真，循环体的语句就会一起执行
语句1
语句2
修改判断条件中的变量，使得循环是可以结束的
#注意缩进
>>> i = 0
>>> while i < 10:
... print i
... i = i + 1
...
0
1
2
3
4
5
6
7
8
9
>>>
i = 0
while i < 3:
i += 1 # i = i + 1
score = raw_input("Please input your score: ")
score = int(score)
if score < 0:
print '你输入错误'
elif score < 60:
print '不及格'
elif score < 70:
print '一般'
elif score < 80:
print '良好'
elif score < 90:
print '优良'
elif score <= 100:
print '优秀'
else:
print '你输入错误'3.while循环练习
往银行存10000元，利率是3.3%，存几年，银行账户能翻一翻？
year = 0 rate = 0.033 money = 10000 while money <= 20000: money = money * (1 + rate) year += 1 print year
输入pc跳出循环，求和及平均值
total = 0
value = 0
cnt = 0
while value != 'pc':
total += int(value)
cnt += 1
value = raw_input("Please input your number:")
if cnt == 0:
print 'total: %s, avg:0' % total
else:
print 'total: %s, avg: %s' % (total, total * 1.0 / cnt)3. 列表（List）简介
list：有序的，可遍历, 可变（可变长、内容可变）集合
python列表可以包含混合类型的数据
chars = ['a', 'b', 'c']
0 , 1 , 2 ....
>>> chars = ['a', 'b', 'c']
>>> chars[0]
'a'
>>> chars[1]
'b'
>>> chars[2]
'c'
>>> chars[6]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IndexError: list index out of range
cast = ["Cleese",'Palin','Jones','Idle']
print(cast)
print(len(cast))
print(cast[1])
['Cleese', 'Palin', 'Jones', 'Idle']
4
Palin
# append(): 从列表末尾增加一个数据项
cast.append("Gilliam")
print(cast)
['Cleese', 'Palin', 'Jones', 'Idle', 'Gilliam']
# pop(): 从列表末尾删除数据
cast.pop()
print(cast)
['Cleese', 'Palin', 'Jones', 'Idle']
# extend(): 扩展一个列表,各数据项之间腹膜逗号隔开,整个列表用中括号挺直
cast.extend(["anzhihe","eto"])
print(cast)
['Cleese', 'Palin', 'Jones', 'Idle', 'anzhihe', 'eto']
# remove(): 从列表中找到并删除一个特定的数据项
cast.remove("eto")
print(cast)
['Cleese', 'Palin', 'Jones', 'Idle', 'anzhihe']
# insert(): 在某个特定的位置前面增加一个数据项
cast.insert(0,"Chapman")
print(cast)
['Chapman', 'Cleese', 'Palin', 'Jones', 'Idle', 'anzhihe']
movies = ["The Holy Grail","The Life of Brian","The Meaning of Life"]
movies.insert(1,1975)
movies.insert(3,1979)
#movies.insert(5,1983)
movies.append(1983)
print(movies)
['The Holy Grail', 1975, 'The Life of Brian', 1979, 'The Meaning of Life', 1983]
索引:(有序)_可以通过索引去访问元素
>>> print chars ['a', 'b', 'c'] >>> chars[1] = 'e' >>> print chars ['a', 'e', 'c']
列表的遍历：
>>> for x in chars: ... print x ... a e c
range
range(start, end)
[start, start+1, start+2, ....,end-1]
>>> range(0,10) [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] >>> for i in range(0, 10): ... print i ... 0 1 2 3 4 5 6 7 8 9
4.遍历列表统计次数
languages = ['C','js','python','js','css','js','html','node','js','python','js','css','js','html','node','js','python','js','css','js','html','node','css','js','html','node','js','python','js','css','js','html','node','js','python','js','css','js','html','node'] cnt = 0 for l in languages: if l == 'js': cnt += 1 print 'js的次数：%s' % cnt
5.选出列表内的最大值
num_list = [-10, -2, -1, 0, 2, 11, 32, 148, 1, 20] num_max = None for num in num_list: if num_max is None: num_max = num elif num_max < num: num_max = num print 'num_max in num_list is :%s' % num_max
4. break & continue
break终止跳出整个循环，continue只终止本次循环
>>> for i in range(0, 10): ... if i == 5: ... break ... print i ... 0 1 2 3 4 >>> for i in range(0, 10): ... if i == 5: ... continue ... print i ... 0 1 2 3 4 6 7 8 9
6.判断是不是闰年
是100的倍数且是400的倍数
不是100的倍数，是4的倍数
输入年份判断是否是闰年，输入quit表示退出
while True: year = raw_input('Please input year:') if year == 'quit': break year = int(year) if year % 100 == 0 and year % 400 == 0: print '闰年' elif year % 100 != 0 and year % 4 == 0: print '闰年' else: print '非闰年'
5. dict简介
dict 就是 key value的键值对，通过key值访问，索引有意义
>>> user_data = {'name':'anzhihe'} #定义dict
>>> print user_data['name'] #获取dict值
anzhihe
>>> user_data['age'] = 0 #增加新值
>>> print user_data['age']
0
>>> user_data['age'] = 20 #修改值
>>> print user_data['age']
207.统计列表中每个字符串出现的次数
langs = ['C','js','python','js','css','js','html','node','js','python','js','css','js','html','node','js','python','js','css','js','html','node','css','js','html','node','js','python','js','css','js','html','node','js','python','js','css','js','html','node']
langs_dict = {}
for lang in langs:
if lang not in langs_dict:
langs_dict[lang] = 1
else:
langs_dict[lang] += 1
print langs_dict
