python无限循环

var = 1
while var == 1:  # 该条件永远为true，循环将无限执行下去
    num = input("Enter a number  :")  # 此时的num为string类型
    print("You entered: ", num)
    if num == str(0):
        print("Good bye!")
        break

循环使用 else 语句

在 python 中，while … else 在循环条件为 false 时执行 else 语句块：

 #!/usr/bin/python
count = 0
while count < 5:
   print count, " is  less than 5"
   count = count + 1
else:
   print count, " is not less than 5"