流程控制之while迴圈
1.什麼是迴圈
迴圈就是重複做某件事
2.為什麼要有迴圈
為了讓計算機能夠具備人重複做某件事的能力
3.如何用迴圈
while語法：
while 條件：
code1
code2
code3
結束while迴圈的兩種方式：
1.修改條件：等到下一次迴圈開始時判斷條件為假才會結束while迴圈
2.break：直接結束本層迴圈
tag=False 到下次判斷才會結束
break 直接結束

# count =0
# while count<3:
# inp_name =input('your name:')
# inp_pwd = input('your pwd:')
# if inp_name == 'egon'and inp_pwd=='123':
# print('success!')
# break
# else:
# print('name or pwd error!')
# count+=1

# count =0
# while True:
# inp_name = input('your name:')
# inp_pwd =input('uor pwd:')
# if inp_name =='egon'and inp_pwd=='123':
# print('success!')
# break
# else:
# print('name or pwd error!')
# count+=1
# if count ==3:
# print('too many tries...')
# break

一：while+continue
continue:結束本次迴圈，直接進入下一次迴圈

# 不合理示範1：
# while True:
# print(1)
# print(2)
# print(3)
# # continue

# 不合理示範2：
# while True:
# print(1)
# print(2)
# if 1 == 2:
# pass
# else:
# print('xxxx')
# continue

# 案例一：
# n=0
# while n < 6: #n=6
# if n == 4:
# n+=1
# continue
# print(n)
# n+=1 
二：while迴圈巢狀

# 案例一：
#name='egon'
#pwd='123'
#count=0
# while True:
# inp_name=input('please input your name: ')
# inp_pwd=input('please input your password: ')
# if inp_name == name and inp_pwd == pwd:
# print('login successful')
#
# while True:
# print("""
# 0 退出
# 1 取款
# 2 轉賬
# 3 查詢
# """)
# cmd = input('請輸入指令編號>>>: ') # cmd='0'
# if cmd == '0':
# break
# elif cmd == '1':
# print('取款...')
# elif cmd == '2':
# print('轉賬...')
# elif cmd == '3':
# print('查詢...')
# else:
# print("輸入錯誤指令，請重新輸入")
# break
# else:
# print('user or password error')
# count+=1 #count=3
#
# if count == 3:
# print('too many tries.....')
# break

# 案例二：
#name='egon'
#pwd='123'
#count=0
# tag=True
# while tag:
# inp_name=input('please input your name: ')
# inp_pwd=input('please input your password: ')
# if inp_name == name and inp_pwd == pwd:
# print('login successful')
#
# while tag:
# print("""
# 0 退出
# 1 取款
# 2 轉賬
# 3 查詢
# """)
# cmd = input('請輸入指令編號>>>: ') # cmd='0'
# if cmd == '0':
# tag=False
# elif cmd == '1':
# print('取款...')
# elif cmd == '2':
# print('轉賬...')
# elif cmd == '3':
# print('查詢...')
# else:
# print("輸入錯誤指令，請重新輸入")
#
# else:
# print('user or password error')
# count+=1 #count=3
#
# if count == 3:
# print('too many tries.....')
# break

# count =True
# while count:
# inp_name= input('your name:')
# inp_pwd = input('your pwd:')
# if inp_name =='egon' and inp_pwd=='123':
# print('success!')
# while count:
# print('''
# 0 退出
# 1 取款
# 2 轉賬
# 3 查詢
# ''')
# cmd=input('請輸入指令編號>>>:')
# if cmd =='0':
# count=False
# elif cmd=='1':
# print('取款。。')
# elif cmd=='2':
# print('轉賬。。。')
# elif cmd =='3':
# print('查詢')
# else:
# print('請輸入指定的指令編號：')
#
# else:
# print('your name or pwd error')
# count +=1
# if count ==3:
# print('too many tries')
# break

# 三：while+else
#else:如果while迴圈沒有被break打斷過，即正常執行完畢後才會執行else的子程式碼

# n=0
# while True:
# if n ==3:
# break
# print(n)
# n+=1
# else:
# print('run..')

# n=0
# while n<=3:
# print(n)
# n+=1
# else:
# print('run..')
#

# n= 0
# while n<=3:
# print(n)
# n+=1
# else:
# print('run,,')

for 迴圈 在迴圈取值方面比while迴圈更為簡潔

# lis =[1,2,3,4,5,6]
# i = 0
# while i<len(lis):
# print(lis[i])
# i+=1

# dic={'name':'egon','age':18,'sex':'male'}
# for k in dic:
# print(k,dic[k])

# for+break
# for+continue
# for+else

# lis =[1,2,3,4,5,6]
# for i in lis:
# print(i)

# dic = {'name':'egon','age':18,'sex':'male'}
# for item in dic:
# print(item,dic[item])

#
# dic = {'name':'egon','age':18,'sex':'male'}
# for k in dic:
# # if k =='age':break
# print(k,dic[k])
# else:
# print('run..')

# dic ={'name':'egon','age':18,'sex':'male'}
# for k in dic :
# print(k,dic[k])
# else:
# print('run..')

# for i in range(1,5,2):
# print(i)

可變不可變型別

可變型別：值改變，但是ID不變，證明是改變原值
不可變型別：值改變，id也變，證明是產生了新之，沒有改變原值，例如整型