实验4 函数与异常处理编程

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task 1

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

 question:task1.py源码中，共有4处有python语句print(sum)（line1, line3, line7, line11)。这4处使用的标识符sum是代表一个变量名吗？如果不是，请分别指出这4行中变量sum的作用域。

answer:不是。

1.Built-in

2.Global

3.Local

4.Global 

task 2_1

 1 def func1(a,b,c,d,e,f):
 2     '''
 3     返回参数a,b,c,d,e,f构成的列表
 4     默认，参数按位置传递；也支持关键词传递
 5     '''
 6     return [a,b,c,d,e,f]
 7 
 8 
 9 def func2(a,b,c,*,d,e,f):
10     '''
11     返回参数a,b,c,d,e,f构成的列表
12     *后面的参数只能按关键词传递
13     '''
14     return [a,b,c,d,e,f]
15 
16 
17 def func3(a,b,c,/,d,e,f):
18     '''
19     返回参数a,b,c,d,e,f构成的参数
20     /前面的参数只能按位置传递
21     '''
22     return[a,b,c,d,e,f]
23 
24 
25 print( func1(1,9,2,0,5,3))
26 print( func1(a = 1,b = 9,c = 2,d = 0,e = 5,f = 3))
27 print( func1(1,9,2,f = 3,d = 0,e = 5))
28 
29 print( func2(11,99,22,d = 0,e = 55,f = 33))
30 print( func2(a = 11,b = 99,c = 22,d = 0,e = 55,f = 33))
31 
32 print( func3(111,999,222,0,555,333))
33 print( func3(111,999,222,d = 0,e = 555,f = 333))

line30后增加一行函数

 1 def func1(a,b,c,d,e,f):
 2     '''
 3     返回参数a,b,c,d,e,f构成的列表
 4     默认，参数按位置传递；也支持关键词传递
 5     '''
 6     return [a,b,c,d,e,f]
 7 
 8 
 9 def func2(a,b,c,*,d,e,f):
10     '''
11     返回参数a,b,c,d,e,f构成的列表
12     *后面的参数只能按关键词传递
13     '''
14     return [a,b,c,d,e,f]
15 
16 
17 def func3(a,b,c,/,d,e,f):
18     '''
19     返回参数a,b,c,d,e,f构成的参数
20     /前面的参数只能按位置传递
21     '''
22     return[a,b,c,d,e,f]
23 
24 
25 print( func1(1,9,2,0,5,3))
26 print( func1(a = 1,b = 9,c = 2,d = 0,e = 5,f = 3))
27 print( func1(1,9,2,f = 3,d = 0,e = 5))
28 
29 print( func2(11,99,22,d = 0,e = 55,f = 33))
30 print( func2(a = 11,b = 99,c = 22,d = 0,e = 55,f = 33))
31 print( func2(11,99,22,0,55,33))
32 
33 print( func3(111,999,222,0,555,333))
34 print( func3(111,999,222,d = 0,e = 555,f = 333))

错误提示信息

line33后，增加一行函数调用

 1 def func1(a,b,c,d,e,f):
 2     '''
 3     返回参数a,b,c,d,e,f构成的列表
 4     默认，参数按位置传递；也支持关键词传递
 5     '''
 6     return [a,b,c,d,e,f]
 7 
 8 
 9 def func2(a,b,c,*,d,e,f):
10     '''
11     返回参数a,b,c,d,e,f构成的列表
12     *后面的参数只能按关键词传递
13     '''
14     return [a,b,c,d,e,f]
15 
16 
17 def func3(a,b,c,/,d,e,f):
18     '''
19     返回参数a,b,c,d,e,f构成的参数
20     /前面的参数只能按位置传递
21     '''
22     return[a,b,c,d,e,f]
23 
24 
25 print( func1(1,9,2,0,5,3))
26 print( func1(a = 1,b = 9,c = 2,d = 0,e = 5,f = 3))
27 print( func1(1,9,2,f = 3,d = 0,e = 5))
28 
29 print( func2(11,99,22,d = 0,e = 55,f = 33))
30 print( func2(a = 11,b = 99,c = 22,d = 0,e = 55,f = 33))
31 
32 print( func3(111,999,222,0,555,333))
33 print( func3(111,999,222,d = 0,e = 555,f = 333))
34 print( func3(a = 111,b = 999,c = 222,0,555,333))

错误提示信息

task2_2

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

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

answer:是

task2_3

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))

task3

 1 def solve(a,b,c):
 2     '''
 3     求解一元二次方程，返回方程的两个根
 4     :param a,b,c: int 方程系数
 5     :return: tuple
 6     '''
 7     delta = b*b-4*a*c
 8     delta_sqrt = abs(delta)**0.5
 9     p1 = -b/2/a
10     p2 = delta_sqrt/2/a
11 
12     if delta>=0:
13         root1 = p1 + p2
14         root2 = p1 - p2
15     else:
16         root1 = complex(p1,p2)
17         root2 = complex(p1,-p2)
18 
19     return root1,root2
20 
21 
22 while True:
23     try:
24         a,b,c = eval(input('Enter eqution coefficient:'))
25         if a == 0:
26             raise
27     except:
28         print('invalid input,or,a is zero')
29         break
30     else:
31         root1,root2 = solve(a,b,c)
32         print(f'root1 = {root1:.2f},root2 = {root2:.2f}')
33         print()

在line22之前增加一行代码

 1 def solve(a,b,c):
 2     '''
 3     求解一元二次方程，返回方程的两个根
 4     :param a,b,c: int 方程系数
 5     :return: tuple
 6     '''
 7     delta = b*b-4*a*c
 8     delta_sqrt = abs(delta)**0.5
 9     p1 = -b/2/a
10     p2 = delta_sqrt/2/a
11 
12     if delta>=0:
13         root1 = p1 + p2
14         root2 = p1 - p2
15     else:
16         root1 = complex(p1,p2)
17         root2 = complex(p1,-p2)
18 
19     return root1,root2
20 
21 print(solve.__doc__)
22 while True:
23     try:
24         a,b,c = eval(input('Enter eqution coefficient:'))
25         if a == 0:
26             raise
27     except:
28         print('invalid input,or,a is zero')
29         break
30     else:
31         root1,root2 = solve(a,b,c)
32         print(f'root1 = {root1:.2f},root2 = {root2:.2f}')
33         print()

task4

 1 def list_generator(a,b,c = 1):
 2     y = []
 3     while a<=b:
 4         y.append(a)
 5         a+=c
 6     return y
 7 
 8 list1 = list_generator(-5,5)
 9 print(list1)
10 list2 = list_generator(-5,5,2)
11 print(list2)
12 list3 = list_generator(1,5,0.5)
13 print(list3)

task 5

 1 def is_prime(n):
 2     x = 2
 3     m = True
 4     if n == 2:
 5         return True
 6     while n > x:
 7         if n%x == 0 and m == True:
 8             m = False
 9         else:
10             x+=1
11     return m
12 
13 for number in range(2,21,2):
14     for x in range(2,int(number/2)+1):
15         y = number-x
16         if is_prime(x) == True and is_prime(y) == True:
17             print('{}={}+{}'.format(number,x,y))
18             break

task6

 1 def encorder(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 decorder(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 print(f'编码后的文本；{encorder(text)}')
25 print(f'解码后的文本；{decorder(encorder(text))}')

task7

 1 def collatz(n):
 2     if n%2 == 0:
 3         return n/2
 4     else:
 5         return 3*n+1
 6 
 7 try:
 8     n =int(input('Enter a positive integer:'))
 9     if n > 0:
10         list = []
11         while n != 1:
12             list.append(n)
13             n = collatz(n)
14         list.append(1)
15         print(list)
16     else:
17         print('Error:must be a positive integer')
18 except:
19     print('Error:must be a positive integer')

实验总结：

1.对于try...except...的使用仍不熟练，需要加强练习

2.对于chr(),ord()的使用仍不熟练，需要加强练习

3.对于函数的编写能力有了一定的提升，希望自己能够继续努力

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