A: while usage
"" "
The while condition ():
when the conditions are met, do 1 thing
when the conditions are met, do 2 things
...
" ""
#1.定义一个整数变量，记录循环的次数
i = 1
#2.开始循环
while i <= 3:
#希望循环内执行的代码
print('hello python')
#处理计数器
i += 1
while infinite loop:
#定义死循环,会一直执行下去
while True:
print('hello python')
Example 1: summing the number between 0 and 100
#1.定义一个整数记录循环的次数
i = 0
#2.定义最终结果的变量
result = 0
#3.开始循环
while i <= 100:
print(i)
#4.每次循环都让result和i这个计数器想加
result += i
#5.处理计数器
i += 1
print('0~100之间的数字求和结果为 %d' %result)
Examples 2: while implementing user login requirements
trycount = 0
while trycount < 3:
name = input('用户名:')
passwd = input('密码:')
if name == 'root' and passwd == 'westos':
print('登录成功')
break
else:
print('登录失败')
print('您还剩余%d次机会' %(2 - trycount))
trycount += 1
else:
print('登录次数超过三次，请稍后登录')
