for循环与内置方法详解

'''
for循环与内置方法详解
'''

# 循环:重复(按照某种规律的)做一件事情


# lt = [1, 2, 3, 4]
#
# ind = 0
#
# while True:
#     print(lt[ind])
#
#     ind += 1

# dic = {'a': 1, 'b': 2, 'c': 3}

# while循环:可以循环一切事物
# for循环:提供了一种手段,不依赖索引取值


#
# for i in dic:
#     print(i,dic[i])

'''
for 变量名(会拿到容器类元素的每一个值,没有了就结束循环) in 容器类元素:
    print(变量名)
'''
# lt = [1, 2, 3, 4]
#
# for i in lt:
#     print(i)

# dic = {'a': 1, 'b': 2, 'c': 3}
#
# count = 0
# for i in dic:  # 对于字典,for循环只能拿到key
#     # print(i, dic[i])
#     print(count)
#     count += 1



# print(list(range(10)))

# for i in range(50,101):  # 顾头不顾尾
#     print(i)

# for i in range(50,101,3):  # 顾头不顾尾,2表示步长
#     print(i)



# for + break
# for i in range(50,101,3):  # 顾头不顾尾,2表示步长
#     if i == 53:
#         break  # 中断循环
#     print(i)

# for + continue
# for i in range(50,101,3):  # 顾头不顾尾,2表示步长
#     if i == 53:
#         continue  # 跳出本次循环,不执行下面的代码
#     print(i)

# for + else(仅作了解):for循环不被break终止就执行else下的代码,否则不执行
# for i in range(50,101,3):
#     if i == 1000:
#         break
#     print(i)
# else:u
#     print('如果没有被break终止我就打印')

'''
Loading....
'''

# print(1,end=' ')  # end是打印1后额外做的操作
# print(2,end=' ')
# print(3,end=' ')
#
# import time
# print(1)
# time.sleep(5)
# print(2)

print('Loading',end='')
import time
for i in range(4):

    print('.',end='')
    time.sleep(0.2)
# 整型
# 浮点型
# 字符串
# 列表
# 元组
# 字典
# 集合
# 布尔值


# lt = [1, 2, 34, 54, 5, 45, 0, 1000]
# lt.sort(reverse=True)  # 死记硬背
# print(lt)

# 整型 int

# 1. 作用:年龄/id

# 2. 定义方式
x = 10

# 3. 使用方法: + - * / % // ** < <= > >= == !=

# 4. 有序or无序(有索引的就有序,无索引的就无序)
# 压根就没有有序无序一说

# 5. 可变or不可变(值变id不变叫可变,值变id变叫不可变):整型不可变
# x = 10
# print(id(x))
# x += 1
# print(id(x))

# lt = [1, 2, 3]
# print(id(lt))
# lt.append(4)
# print(lt)
# print(id(lt))


# 浮点型float


# 1. 作用: 薪资

# 2. 定义方式
x = 10.1

# 3. 使用方法: + - * / % // ** > >= < <= == !=


# 4. 有序or无序: 压根没有有序无序一说


# 5. 可变or不可变:不可变
x = 10.1
print(id(x)
      )
x +=1
print(id(x))
# 字符串str
# 1. 作用:姓名

# 2. 定义方式
# 单引号/双引号/三单引号/三双引号


# 3. 使用方法

## 优先掌握(今天就得掌握)
# 1. 索引
# 左    右
s = 'nick handsome'
#    01234567
#              -2-1
print(s[1])

# 2. 索引切片
print(s[0:4])  # 顾头不顾尾
print(s[0:4:2])  # 2表示步长,隔一个取一个
print(1, s[4:0:-1])  # +从左到右,-表示从右到左
print(1, s[2:])  # 左边的不写取到最左边,右边的不写取到最右边

# 3. for循环
for i in s:
    print(4, i)

# 4. 成员运算
print('nick' in s)
print('nick1' not in s)  # True

# 5. strip()  # 默认去除两端空格,可以指定去除的字符,可以指定多个字符同时去掉
s1 = 'a  nick   ******'
# print(s1.strip())
print(s1.strip(' kc*'))  # 可以乱序,但是不能没有

# 6. split() # 切割
s2 = 'nick|123658|180|140'
print(s2.split('|'))  # 按照|切割字符串,得到的是一个列表

# 7. len长度
s1 = 'nick handsome'
print(len(s1))

## 需要掌握(一周内掌握)

# lstrip&rstrip
s3 = '**nick**'
print(s3.lstrip('*'))
print(s3.rstrip('*'))

# lower&upper
s3 = 'Nick'
print(s3.lower())  # 小写
print(s3.upper())  # 大写

# startswith&endswith
s4 = 'nick handsome'
print(s4.startswith('nick'))  # 以。。。开始
print(s4.endswith('some'))  # 以。。。结束

# rsplit
s = 'nick|handsome|180|140|'
#    01234
# print('range(len(s))',range(len(s)))
# lt = []
# ind = -1
# for i in range(len(s)):
#     if s[i] == '|':
#         lt.append(s[ind+1:i])
#         ind = i # ind = 4
#
# print('lt', lt)

print(s.split('|',1))
print(s.rsplit('|',1))  # 从右切割

# join
s = 'nick|handsome|180|140'
lt = s.split('|')
print(lt)
# 用*拼接列表内的每一个元素
# new_s = ''
# for i in lt:
#     i += '*'
#     new_s += i
# print(new_s)
print('*'.join(lt))  # 使用*拼接列表内的每一个元素

# replace
s = 'nick handsome'
s = s.replace('nick','nick chen')
print(s)

# isdigit/isalpha
s = 'a123123'
print(s.isdigit())  # 判断字符串内字符是否都为数字
s = 'askdlfj234'
print(s.isalpha())


# pwd = input('请输入你的密码:')
# if not pwd.isdigit():
#     print('请输入纯数字')

## 了解(看到能够想起来就行)

# find|rfind|index|rindex|count
s = 'nick handsome'
print(s.find('h'))  # 找索引,-1表示没找到
print(s.rfind('h',6,10))

print(s.index('h'))
# print(s.index('sadf'))  # 找不到报错
# print(s.find('sadf'))  # 找不到返回-1

s = 'aaaaacccc'
print(s.count('a'))

# center|ljust|rjust|zfill
s = 'nick'
print(s.center(50,'*')) # 居中
print(s.ljust(50,'*'))
print(s.rjust(50,'*'))
s = '111'
print(s.zfill(8))

# expandtabs
# 
 换行
# 	 缩进
s = 'a				a'
print(s)
print(s.expandtabs(18))

# captalize|swapcase|title
s = 'nickNick handsome'
print(s.capitalize())  # 首字母大写
print(s.swapcase())
print(s.title())  # 每个单词的首字母大写


# is系列:有兴趣看一看,没兴趣算了

# 4. 有序or无序:有序


# 5. 可变or不可变:不可变
s = 'nick'
print(id(s))
s += 'nick'
print(id(s))
class SelfList(list):
    def self_sort(self):
        for i in range(len(self)):  # [0,1,2,3,4,5]
            for j in range(len(self)):  # [0,1,2,3,4,5]
                if self[i] < self[j]:
                    self[i], self[j] = self[j], self[i]


lt = SelfList([2, 0, 4, 3, 5])
lt.sort()
print(lt)
原文地址:https://www.cnblogs.com/jinhongquan/p/11515027.html