标签：
2-2：
（d）代码单独执行时，没有任何输出；在交互式解释器中执行会输出表达式的计算结果。
（e）
#!/usr/bin/env python print 1 + 2 * 4
2-4：
（a）
#!/usr/bin/env python inp = raw_input() print inp
（b）
#!/usr/bin/env python inp = int(raw_input()) print inp
2-5：
（a）
#!/usr/bin/python a = 0 while a <= 10: print a a += 1
（b）
#!/usr/bin/env python for item in range(11): print item
2-6:
固定数值：
#!/usr/bin/env python num = ‘a‘ if type(num) in (int, float): if num < 0: print ‘num is less than 0‘ elif num > 0: print ‘num is greater than 0‘ else: print ‘num is equal to 0‘ else: print ‘invalid num‘
获取输入：
#!/usr/bin/env python num = float(raw_input(‘Enter a number: ‘)) if num < 0: print ‘num is less than 0‘ elif num > 0: print ‘num is greater than 0‘ else: print ‘num is equal to 0‘
2-7：
while实现
#!/usr/bin/python mystr = raw_input(‘Enter a string: ‘) index = 0 while index < len(mystr): print mystr[index] index += 1
for实现
#!/usr/bin/python myStr = raw_input(‘Enter a number: ‘) for c in myStr: print c
2-8：
固定数值，while实现：
#!/usr/bin/env python aList = [1,2,3,4,5] index = 0 s = 0 while index < len(aList): s += aList[index] index += 1 print s
固定数值，for实现：
#!/usr/bin/env python aList = [1,2,3,4,5] s = 0 for item in aList: s += item print s
用户输入，while实现：
#!/usr/bin/env python a = 0 s = 0 while a < 5: s += int(raw_input(‘->‘)) a += 1 print s
用户输入，for实现：
#!/usr/bin/env python s = 0 print ‘Enter 5 numbers:‘ for i in range(5): s += int(raw_input(‘->‘)) print s
2-9：
#!/usr/bin/env python aList = [1,2,5,6,7] s = 0 for item in aList: s += item ans = float(s) / len(aList) print ans
2-10：
#!/usr/bin/env python while True: num = float(raw_input(‘Enter a number between 1 and 100: ‘)) if 1 < num < 100: print ‘succeed‘ break else: print ‘the number is not between 1 and 100‘
2-11:
#!/usr/bin/env python print ‘Enter 5 numbers:‘ s = 0 for i in range(5): s += float(raw_input(‘->‘)) while True: print ‘1. get the sum of 5 numbers‘ print ‘2. get the avg of 5 numbers‘ print ‘X. exit‘ i = raw_input() if i == ‘1‘: print s elif i == ‘2‘: print s / 5 elif i == ‘x‘ or i == ‘X‘: break
2-12:
（a）键入dir()后出现：
[‘__builtins__‘, ‘__doc__‘, ‘__name__‘, ‘__package__‘]
打印各值的结果如下：
__guiltins__: <module ‘__builtin__‘ (built-in)>
__doc__: None
__name__: __main__
__package__: None
（b）返回信息如下：
<built-in function dir>
此信息表示dir是一个内建函数
（c）type(dir)的结果为：<type ‘builtin_function_or_method‘>
2-14:
print ((-2) * 4) + (3 ** 2)
2-15
（a）:
#!/usr/bin/env python print ‘Please enter 3 numbers:‘ a = int(raw_input(‘->‘)) b = int(raw_input(‘->‘)) c = int(raw_input(‘->‘)) if a > b: a, b = b, a if a > c: a, c = c, a if b > c: b, c = c, b print a, b, c
（b）:
#!/usr/bin/env python print ‘Please enter 3 numbers:‘ a = int(raw_input(‘->‘)) b = int(raw_input(‘->‘)) c = int(raw_input(‘->‘)) if a > b: a, b = b, a if a > c: a, c = c, a if b > c: b, c = c, b print c, b, a
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原文地址：http://www.cnblogs.com/lzl7/p/5192392.html
