一、while循环:

1、 1+2+..100

i = 1
sum = 0
while i <=100:
    sum = sum + i
    i = i + 1
print(sum)
F:\python3.6\python.exe F:/python_workdir/oldboy/while.py
5050

 2、while 的跳出循环

方法一:通过break 

方法二:通过增加条件

i = 1
while i <=6:
    print(i)
    i = i+1

 一旦遇到break,就立马跳出循环,不在执行后面的语句 

i = 1
while True:
    print(i)
    i = i+1
    if i >=6:
        break

 3、while之continue:

count=0
while count <=100:
    count = count + 1
    if count > 5 and count < 95:
        continue
    print("loop" , count)
print("______the end ________")

执行结果:
F:\python3.6\python.exe F:/python_workdir/oldboy/while.py
loop 1
loop 2
loop 3
loop 4
loop 5
loop 95
loop 96
loop 97
loop 98
loop 99
loop 100
loop 101
______the end ________
continue的意思是遇到它就立即结束本次循环(不是终止循环),然后开始返回继续下一次的循环,所以当count=6的时候,第一次遇到continue,结束本次循环,后面的语句不在执行,所以没打印,继续下一次的循环
continue就是“见底”

 使用while打印1 2 3 4 5 6 8 9 10  (没有7) 

count=0
while count <10:
    count = count + 1
    if count == 7:
        continue
    else:
        print(count)

这里的continue也可替换为pass,这也是个关键字,遇到pass什么都不执行