实验4 函数与异常处理编程

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')