习题 33: While 循环
在文本编辑器中，编辑以下内容并保存到ex33.py文件中，同时在终端中运行该文件：
#coding:utf-8
i = 0
numbers = []
while i < 6:
print "At the top i is %d" % i
numbers.append(i)
i = i + 1
print "numbers now：", numbers
print "At the bottom i is %d" % i
print "The numbers is:"
for num in numbers:
print num
执行结果：
$ python ex33.py
At the top i is 0
numbers now： [0]
At the bottom i is 1
At the top i is 1
numbers now： [0, 1]
At the bottom i is 2
At the top i is 2
numbers now： [0, 1, 2]
At the bottom i is 3
At the top i is 3
numbers now： [0, 1, 2, 3]
At the bottom i is 4
At the top i is 4
numbers now： [0, 1, 2, 3, 4]
At the bottom i is 5
At the top i is 5
numbers now： [0, 1, 2, 3, 4, 5]
At the bottom i is 6
The numbers is:
0
1
2
3
4
5
加分习题
- 将这个 while 循环改成一个函数，将测试条件(i < 6)中的 6 换成一个变量。
#coding:utf-8
i = 0
numbers = []
x = int(raw_input("please input the number:")) # 注意要使用int类型转换，不然会导致程序运行停不下来
while i < x:
print "At the top i is %d" % i
numbers.append(i)
i = i + 1
print "numbers now：", numbers
print "At the bottom i is %d" % i
print "The numbers is:"
for num in numbers:
print num
执行结果：
$ python ex33.py
please input the number:4
At the top i is 0
numbers now： [0]
At the bottom i is 1
At the top i is 1
numbers now： [0, 1]
At the bottom i is 2
At the top i is 2
numbers now： [0, 1, 2]
At the bottom i is 3
At the top i is 3
numbers now： [0, 1, 2, 3]
At the bottom i is 4
The numbers is:
0
1
2
3
使用这个函数重写你的脚本，并用不同的数字进行测试。
为函数添加另外一个参数，这个参数用来定义第 8 行的加值 + 1 ，这样你就可以 让它任意加值了。
i = 0
numbers = []
x = int(raw_input("please input the end number:"))
y = int(raw_input("please input the step:"))
while i < x:
print "At the top i is %d" % i
numbers.append(i)
i = i + y #加参数y
print "numbers now：", numbers
print "At the bottom i is %d" % i
print "The numbers is:"
for num in numbers:
print num
执行结果：
$ python ex33.py
please input the end number:14
please input the step:2
At the top i is 0
numbers now： [0]
At the bottom i is 2
At the top i is 2
numbers now： [0, 2]
At the bottom i is 4
At the top i is 4
numbers now： [0, 2, 4]
At the bottom i is 6
At the top i is 6
numbers now： [0, 2, 4, 6]
At the bottom i is 8
At the top i is 8
numbers now： [0, 2, 4, 6, 8]
At the bottom i is 10
At the top i is 10
numbers now： [0, 2, 4, 6, 8, 10]
At the bottom i is 12
At the top i is 12
numbers now： [0, 2, 4, 6, 8, 10, 12]
At the bottom i is 14
The numbers is:
0
2
4
6
8
10
12
- 再使用该函数重写一遍这个脚本。看看效果如何。
- 接下来使用 for-loop 和 range 把这个脚本再写一遍。你还需要中间的加值操作吗?如果你不去掉它，会有什么样的结果?
#coding:utf-8
i = 0
numbers = []
for i in range(6):
print "At the top i is %d" % i
numbers.append(i)
print "numbers now：", numbers
print "At the bottom i is %d" % i
print "The numbers is:"
for num in numbers:
print num
执行结果：
At the top i is 0
numbers now： [0]
At the bottom i is 0
At the top i is 1
numbers now： [0, 1]
At the bottom i is 1
At the top i is 2
numbers now： [0, 1, 2]
At the bottom i is 2
At the top i is 3
numbers now： [0, 1, 2, 3]
At the bottom i is 3
At the top i is 4
numbers now： [0, 1, 2, 3, 4]
At the bottom i is 4
At the top i is 5
numbers now： [0, 1, 2, 3, 4, 5]
At the bottom i is 5
The numbers is:
0
1
2
3
4
5
注意：很有可能你会碰到程序跑着停不下来了，这时你只要按着 CTRL 再敲 c (CTRL-c)， 这样程序就会中断下来了。
