Python练习（一）

【输出除7以外的所有1至10以内的正整数】

start = 1
while True:
     if start ==7:
          start += 1
          continue
     print(start)
     if start ==10:
     break
     start +=1

 

【求1-100以内所有整数的和】

 

sum = 0
start = 1
while True:
     print(start )
     sum = sum+start
     if start == 100
          break
     start  += 1

 

【输出1-100内的所有奇数】

 

start = 1
flag = True
while flag:
    if start%2==1:
        print(start)
    else:
        pass
    if start == 100:
        flag = False
    else:
        start += 1
print("end")

  

【输出1-100内所有的偶数】

 

start = 1
flag = True
while flag:
    if start%2!=1:
        print(start)
    else:
        pass
    if start == 100:
        flag = False
    else:
        start += 1
print("end")

 

【求1-2+3-4...+99的所有数的和】

 

start = 1
sum = 0
flag = True
while flag:
    if start%2==1:
        sum = sum+start
    else:
        sum = sum-start
    if start == 99:
        flag = False
    else:
        start += 1
print(sum)

 

【用户登录（三次机会重试）】

 

start = 1
flag = True
while flag:
    name = input("Username:")
    pwd = input("Password:")
    if name == "zjw" and pwd == "123":
        print("恭喜你,登陆成功!")
        break
    else:
        print("用户名或密码错误!Try again~")
    if start == 3:
        print("登陆失败！")
        flag = False
    else:
        start += 1