循环

循环

for循环

# for 循环
total = 0
for i in range(100000):
    total += i
print(total)  # 4999950000

while 循环

while <condition>:
     <statesments>
    

Python会循环执行statesments，直到condition不满足为止。

i = 0
total = 0
while i <= 100:
    total += i
    i += 1
print(total)  # 5050

举个例子，通过while遍历集合：

# 空容器会被当成False，因此可以用while循环读取容器的所有元素
plays = set(['Hamlet', 'Mac', 'King'])
while plays:
    play = plays.pop()
    print('Perform', play)

continue 语句

遇到 continue 的时候，程序会返回到循环的最开始重新执行。

values = [7, 6, 4, 7, 19, 2, 1]
for i in values:
    if i % 2 != 0:
        # 忽略奇数
        continue
    print(i)
# 6
# 4
# 2

break 语句

遇到 break 的时候，程序会跳出循环，不管循环条件是不是满足

command_list = ['start',
                '1',
                '2',
                '3',
                '4',
                'stop',
                'restart',
                '5',
                '6']
while command_list:
    command = command_list.pop(0)
    if command == 'stop':
        break
    print(command)
# start
# 1
# 2
# 3
# 4