实验4 函数与异常处理编程

task1.py

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)

运行结果

答：不是同一个对象的名称。line1是内置作用域，line3、line11的sum是全局作用域，line7的sum是局部作用域

task2_1.py

 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) )

运行结果

task2_2.py

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

运行结果

答：内置函数sorted（）中参数reverse一定要用关键字传递

task2_3.py

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

运行结果

task3.py

def solve(a, b, c):
    '''
    求解一元二次方程, 返回方程的两个根
    :para: a,b,c: float 方程系数
    :return: tuple
    '''
    delta = b*b - 4*a*c
    delta_sqrt = abs(delta)**0.5
    p1 = -b/2/a
    p2 = delta_sqrt/2/a
    if delta >= 0:
        root1 = p1 + p2
        root2 = p1 - p2
    else:
        root1 = complex(p1, p2)
        root2 = complex(p1, -p2)
    return root1, root2

print(solve.__doc__)
while True:
    try:
        t = input('输入一元二次方程系数a b c, 或者，输入#结束: ')
        if t == '#':
            print('结束计算，退出')
            break
        a, b, c = map(float, t.split())
        if a == 0:
            raise ValueError('a = 0, 不是一元二次方程')
    except ValueError as e:
        print(repr(e))
        print()
    except:
        print('有其它错误发生\n')
    else:
        root1, root2 = solve(a, b, c)
        print(f'root1 = {root1:.2f}, root2 = {root2:.2f}')
        print()

运行结果

task4.py

def list_generator(a,b,c=1):
    lst = []
    while a<=b:
        lst.append(a)
        a += c
    return lst

list1 = list_generator(-5, 5)
print(list1)
list2 = list_generator(-5, 5, 2)
print(list2)
list3 = list_generator(1, 5, 0.5)
print(list3)

运行结果

task5.py

 1 def is_prime(n):
 2     if n == 2:
 3         return True
 4     elif n != 1:
 5         for i in range(2,n):
 6             if n == 2:
 7                 return True
 8             elif n % i == 0:
 9                 break
10             else:
11                 return True
12 
13 for i in range(2,20+1,2):
14     flag = True
15     for j in range(2, i):
16         if is_prime(j) == True and is_prime(i - j) == True and flag == True:
17             print(f'{i}={j}+{i-j}')
18             flag = False

运行结果

task6.py

 1 def encoder(text):
 2     ls=list(text)
 3     for i in range(len(ls)):
 4         if 'a'<=ls[i].lower()<='u':
 5             ls[i]=chr(ord(ls[i])+5)
 6         elif 'v'<=ls[i].lower()<='z':
 7             ls[i]=chr(ord(ls[i])-21)
 8         else:
 9             pass
10     return ''.join(ls)
11 
12 def decoder(text):
13     ls=list(text)
14     for i in range(len(ls)):
15         if 'f'<=ls[i].lower()<='z':
16             ls[i]=chr(ord(ls[i])-5)
17         elif 'a'<=ls[i].lower()<='e':
18             ls[i]=chr(ord(ls[i])+21)
19         else:
20             pass
21     return ''.join(ls)
22 
23 
24 text = input('输入英文文本: ')
25 
26 encoded_text = encoder(text)
27 print('编码后的文本: ', encoded_text)
28 
29 decoded_text = decoder(encoded_text)
30 print('对编码后的文本解码: ', decoded_text)

运行结果

task7.py

def collatz(n):
    lst = []
    lst.append(n)
    while n != 1:
        if n %2 == 0:
            n = n/2
            lst.append(int(n))
        else:
            n = n*3 +1
            lst.append(int(n))
    return lst
try:
    n = int(input('Enter a positive integer:'))
    if n <= 0:
        raise ValueError
except ValueError:
    print('Error: must be a positive integer')
else:
    print(collatz(n))

运行结果

task8.py

def func(n):
    if n == 0:
        return 0
    else:
        return 2*func(n-1) + 1

while True:
    x = input()
    if x == '#':
        print('计算结束')
        break
    n = int(x)
    ans = func(n)
    print(f'n = {n}, ans = {ans}')

运行结果