Python005，,1. 数据类型 i
Python005，,1. 数据类型 i
1. 数据类型
int
str
list
tuple
dict
2.for和while
1 #continue 2 #break 3 4 for i in range(1,10): 5 print(i) 6 for i in range(10,20): 7 print(i) 8 9 for i in range(1,10):10 print(i)11 break12 for i in range(10,20):13 print(i)14 for i in range(1,10):15 print(i)16 for i in range(10,20):17 print(i)18 break19 20 for i in range(1,10):21 print(i)22 for i in range(10,20):23 print(i)24 break25 break26 27 for i in range(1,10):28 print(i)29 for i in range(10,20):30 print(i)31 break32 33 flag = False34 for i in range(1,10):35 print(i)36 if flag:37 break38 for i in range(10,20):39 print(i)40 flag = True41 break42 43 ==================44 for i in range(1,10):45 print(i)46 continue47 for i in range(10,20):48 print(i)49 50 for i in range(1,10):51 print(i)52 for i in range(10,20):53 continue54 print(i)55 ===================56 for i in range(1,10):57 print(i) # 1,258 for j in range(i,10): # 2,959 print(j)60 61 62 63 for i in range(1,10):64 print(i) 65 for j in range(10,i,-1): 66 print(j)
3. 编码
ascii - 8
unicode - 16,32
utf-8 - 8 ~ 32
gbk - 16
4. 字符串格式化
- "asdf%s,sdfsdf%d" %(‘11‘,4)
- "asdf%s,sdfsdf" %‘11‘
- "asdf%s,sdfsdf%%" %‘11‘
1 tpl = "我叫%sfdf"2 name1 = tpl %(‘骑兵‘,)3 name2 = tpl %(‘步兵‘,)4 print(name1,name2)
5. 变量
name = ‘xxx‘
注意：
不要使用python中已经使用的变量：list,str,tuple,dict,bool,int
6. 条件语句
if xxx：
pass
elif xxxx:
pass
else:
pass
7. 长度
len(xxxx)
8. 索引操作：
str:
v = "xxxx"
v[0]
tuple:
v = (1,2,3)
v[0]
list:
v = [1,2,3]
v[0]
dict:
v = {
‘k1‘:‘val1‘,
‘k2‘:‘val2‘,
‘k3‘:‘val3‘
}
v[‘k1‘]
9. 运算符
- 除法
- 字符串相乘
- += -+
- or and 顺序
- in
dic = {
‘k1‘: ‘v1‘,
‘k2‘: ‘v2‘
}
li = [11,22,33,44]
# 1.列表，查看是否存在其中
if 11 in li:
pass
# 2.字典，查看key是否在其中
"k1" in dic
for item in dic:
print(item)
for k in dic.keys():
print(k)
if "k1" in dic:
pass
# 3. 字典，查看value是否在其中
查看v是否存在，v1 in dic.values():
# 4. 字典，查看value是否在其中
循环实现，检查“v1”是否在字典 dic = {‘k1‘: ‘v1‘,‘k2‘: ‘v2‘} 的值中。
1 val = "v1" 2 for val in dic: 3 for val in dic.values(): 4 for v in dic.values(): 5 if val in v: 6 print(True) 7 #龙哥，老狗，成绩，海角 8 9 result = False10 for item in dic.values():11 if item == val:12 result = True13 break14 15 print(result)
10. py2，py3
-
raw_input()
input()
-
range()
xrange()
range()
-
ascii(#-*-encoding:utf-8 -*-)
utf-8
-
print "alex"
print(‘alex‘)
11. 字符串
- 大小写
- 首字母大写
- 分割
a,b = split(‘*‘,1)
- 去除空白
- 替换
- "xx".join(["11","22",])
- 是否是十进制数
12. 列表
- 追加
- 插入
- 反转
长度
for循环
del li[0]
li[0:3:1]
嵌套：
[
1,
[33,44],
"xxx"
]
补充：
1. 索引为奇数值，删除
# 删除列表元素时，会影响列表长度，从而使得索引取值时，容易出现错误。
li = [11,22,33,44,66]
1 li = [11, 22, 33, 44, 66] # 02 # 索引为奇数值，删除3 for i in range(0,len(li)): # 4,04 del li[i]5 print(li)
1 # 解决方案一： 2 li = [11, 22, 33, 44, 66] # 0 3 new_list = [] 4 # 索引为奇数值，删除 5 for i in range(0,len(li)): 6 if i%2 == 0: 7 new_list.append(li[i]) 8 li = new_list 9 print(li)10 11 # 解决方案二：12 li = [11, 22, 33, 44, 66] # 013 #索引为奇数值，删除14 for i in range(len(li)-1,-1,-1): # 4,015 if i%2 == 1:16 del li[i]17 print(li)18 19 #切片+步长20 li = [11, 22, 33, 44, 66] 21 del li[0:4]22 del li[0:4:2]23 print(li)
12. tuple
- 元素，不可变
- 只有一个元素时，一定加逗号
# val = (1,2,3,4,555,6)
# print(val,type(val))
# val = (1)
# print(val,type(val))
# val = (1,)
# print(val,type(val))
13. 字典
dic = {‘k1‘:"v1",‘k2‘:‘v2‘}
#方法
data = dic.get(‘kk1‘) # None
len
dict[‘k1‘] = "vv1"
for
val = "v1" in dic # False
# 出错点
# 题：dic = {‘k1‘:"v1",‘k2‘:‘v2‘}把key="k1",键值对删除
# del dic[‘k1‘]
# 题：dic = {‘u1‘:"v1",‘k2‘:‘v2‘,‘k3‘:‘v3‘}把key中存在k,键值对删除
1 dic = {‘u1‘:"v1",‘k2‘:‘v2‘,‘k3‘:‘v3‘} 2 # 不要在循环当前字典的过程中，修改当前字典大小 3 4 # 错误 5 for key in dic: 6 if ‘k‘ in key: 7 del dic[key] 8 9 # 正确方式 10 dic_key_list = []11 for key in dic:12 dic_key_list.append(key)13 14 for row in dic_key_list:15 if ‘k‘ in row:16 del dic[row]17 print(dic)14. int
- 最少用多少二进制位表示
15. 字符串和布尔值相互转换
v = "123"
val = int(v)
v = 123
val = str(v)
list
v = "礼券"
val = ["礼","券"]
v = (1,2,3,)
val = list(v)
此功能相当于：
# val = []
# for item in v:
# val.append(item)
tuple
v = [11,22,33,44]
val = tuple(v)
16. 布尔值
- True,False
- False: 0,None,"",{},[],()
17.字符串功能
for循环
while循环
if else
字典
Python005
评论关闭