吴裕雄--天生自然 PYTHON3开发学习：循环语句

n = 100

sum = 0

counter = 1

while counter <= n:

    sum = sum + counter

    counter += 1

print("1 到 %d 之和为: %d" % (n,sum))

var = 1

while var == 1 :  # 表达式永远为 true

   num = int(input("输入一个数字  :"))

   print ("你输入的数字是: ", num)

print ("Good bye!")

count = 0

while count < 5:

   print (count, " 小于 5")

   count = count + 1

else:

   print (count, " 大于或等于 5")

flag = 1

while (flag): print ('欢迎访问菜鸟教程!')

print ("Good bye!")

for <variable> in <sequence>:

    <statements>

else:

    <statements>

sites = ["Baidu", "Google","Runoob","Taobao"]

for site in sites:

    if site == "Runoob":

        print("菜鸟教程!")

        break

    print("循环数据 " + site)

else:

    print("没有循环数据!")

print("完成循环!")

for letter in 'Runoob':     # 第一个实例

   if letter == 'b':

      break

   print ('当前字母为 :', letter)

var = 10                    # 第二个实例

while var > 0:

   print ('当期变量值为 :', var)

   var = var -1

   if var == 5:

      break

print ("Good bye!")

for letter in 'Runoob':     # 第一个实例

   if letter == 'o':        # 字母为 o 时跳过输出

      continue

   print ('当前字母 :', letter)

var = 10                    # 第二个实例

while var > 0:

   var = var -1

   if var == 5:             # 变量为 5 时跳过输出

      continue

   print ('当前变量值 :', var)

print ("Good bye!")

for n in range(2, 10):

    for x in range(2, n):

        if n % x == 0:

            print(n, '等于', x, '*', n//x)

            break

    else:

        # 循环中没有找到元素

        print(n, ' 是质数')