实验四 函数与异常处理编辑

实验任务一

实验源码

1 print(sum)
2 sum = 42
3 print(sum)
4 def inc(n):
5     sum = n+1
6     print(sum)
7     return sum
8 sum = inc(7) + inc(7)
9 print(sum)

运行测试截图

问题：实验任务1中，共有四处有print(sum)(line1,line3,line7,line11)。这四处使用的标识符sum是同一个对象名称吗?如果不是，请以文字方式回答这4行中标识符sum的作用域。

答：不，line1内置作用域，line3为全局作用域，lline7局部作用域，line11全局作用域。

实验任务二

2-1

实验源码

 1 def func1(a, b, c, d, e, f):
 2     return [a,b,c,d,e,f]
 3 def func2(a, b, c,*, d, e, f):
 4     return [a,b,c,d,e,f]
 5 def func3(a, b, c, /, d, e, f):
 6     return [a,b,c,d,e,f]
 7 
 8 print( func1(1,9,2,0,5,3) )
 9 print( func1(a=1, b=9, c=2, d=0, e=5, f=3) )
10 print( func1(1,9,2, f=3, d=0, e=5))
11 
12 print( func2(11, 99, 22, d=0, e=55, f=33) )
13 print( func2(a=11, b=99, c=22, d=0, e=55, f=33) )
14 
15 print( func3(111, 999, 222, 0, 555, 333))
16 print( func3(111, 999, 222, d=0, e=555, f=333))

运行测试截图

2-2

实验源码

1 list1 = [1, 9, 8, 4]
2 print(sorted(list1))
3 print(sorted(list1, reverse=True))
4 print(sorted(list1, True))

运行测试截图

问题：Python内置函数sorted()中，参数revers的传递方式是否必须使用关键字传递？

答：是

2-3

实验源码

1 def func(a, b, c, /, *, d, e, f):
2     return( [a,b,c,d,e,f] )
3 
4 print(func(1,2,3,d=4,e=5,f=6))

运行测试截图

实验任务三

实验源码

 1 def solve(a, b, c):
 2     delta = b*b - 4*a*c
 3     delta_sqrt = abs(delta)**0.5
 4     p1 = -b/2/a
 5     p2 = delta_sqrt/2/a
 6     if delta >= 0:
 7         root1 = p1 + p2
 8         root2 = p1 - p2
 9     else:
10         root1 = complex(p1, p2)
11         root2 = complex(p1, -p2)
12     return root1, root2
13 while True:
14     try:
15         t = input('输入一元二次方程系数a b c, 或者，输入#结束: ')
16         if t == '#':
17             print('结束计算，退出')
18             break
19         a, b, c = map(float, t.split())
20         if a == 0:
21             raise ValueError('a = 0, 不是一元二次方程')
22     except ValueError as e:
23         print(repr(e))
24         print()
25     except:
26         print('有其它错误发生\n')
27     else:
28         root1, root2 = solve(a, b, c)
29         print(f'root1 = {root1:.2f}, root2 = {root2:.2f}')
30         print()

运行测试截图

运行测试截图

实验任务四

实验源码

 1 def list_generator(start, stop, step=1):
 2     result = []
 3     i = start
 4     while i <= stop:
 5         result.append(i)
 6         i += step
 7     return result
 8 
 9 list1 = list_generator(-5, 5)
10 print(list1)
11 list2 = list_generator(-5, 5, 2)
12 print(list2)
13 list3 = list_generator(1, 5, 0.5)
14 print(list3)

运行测试截图

实验任务五

实验源码

 1 def is_prime(num):
 2     if num == 1:
 3         return False
 4     elif num == 2:
 5         return True
 6     else:
 7         for i in range(2, num):
 8             if num % i == 0:
 9                 return False
10         return True
11 
12 def goldbach_conjecture(num):
13     primes = []
14     for i in range(2, num):
15         if is_prime(i):
16             primes.append(i)
17     for prime in primes:
18         if num - prime in primes:
19             return f"{num} = {prime} + {num-prime}"
20     return None
21 
22 for num in range(4, 21, 2):
23     expression = goldbach_conjecture(num)
24     if expression:
25         print(expression)

运行测试截图

实验任务六

实验源码

 1 def encoder(text):
 2     list = []
 3     for i in text:
 4         if 65 <= ord(i) <= 85 or 97 <= ord(i) <= 117:
 5             list.append(chr(ord(i)+5))
 6         elif 86 <= ord(i) <= 90 or 118 <= ord(i) <= 122:
 7             list.append(chr(ord(i)-21))
 8         else:
 9             list.append(i)
10     return ''.join(list)
11 
12 def decoder(text):
13     list = []
14     for i in text:
15         if 70 <= ord(i) <= 90 or 102 <= ord(i) <= 122:
16             list.append(chr(ord(i)-5))
17         elif 65 <= ord(i) <= 69 or 97 <= ord(i) <= 101:
18             list.append(chr(ord(i)+21))
19         else:
20             list.append(i)
21     return ''.join(list)
22 
23 text = input('输入英文文本：')
24 
25 encoded_text = encoder(text)
26 print('编码后的文本: ', encoded_text)
27 decoded_text = decoder(encoded_text)
28 print('对编码后的文本解码: ', decoded_text)

运行测试截图

实验任务七

实验源码

 1 def collatz(n):
 2     if n%2==0:
 3         return n//2
 4     else:
 5         return (n*3)+1
 6 
 7 
 8 try:
 9     n=eval(input('Enter a positive integer:'))
10     if type(n) is float or type(n) is str or n<=0:
11         raise ValueError('Error:must be a positive integer')
12 except ValueError as e:
13     print(repr(e))
14     print()
15 except:
16     print('Error:must be a positive integer')
17 else:
18     num=collatz(n)
19     list=[n,num]
20     while True:
21         if num!=1:
22             num=collatz(num)
23             list.append(num)
24         else:
25             break
26     print(list)

运行测试截图

实验任务八

实验源码

 1 def func(n):
 2     if n == 0:
 3         return 1
 4     else:
 5         return 2 * func(n-1) + 1
 6 while True:
 7     x = input()
 8     if x == '#':
 9         print('计算结束')
10         break
11     n = int(x)
12     ans = func(n)
13     print(f'n = {n}, ans = {ans}')

运行测试截图