实验4

实验任务1

print(sum)
sum = 42
print(sum)


def inc(n):
    sum = n+1
    print(sum)
    return sum


sum = inc(7) + inc(7)
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 

 

实验任务2

task2_1

def func1(a,b,c,d,e,f):
    '''
    返回参数a,b,c,d,e,f构成的列表
    默认，参数按位置传递；也支持关键词传递
    '''
    return [a,b,c,d,e,f]


def func2(a,b,c,*,d,e,f):
    '''
    返回参数a,b,c,d,e,f构成的列表
    *后面的参数只能按关键词传递
    '''
    return [a,b,c,d,e,f]


def func3(a,b,c,/,d,e,f):
    '''
    返回参数a,b,c,d,e,f构成的参数
    /前面的参数只能按位置传递
    '''
    return[a,b,c,d,e,f]


# func1调用：按位置传递、按参数传递都可以
print( func1(1,9,2,0,5,3))
print( func1(a = 1,b = 9,c = 2,d = 0,e = 5,f = 3))
print( func1(1,9,2,f = 3,d = 0,e = 5))


# func2调用：d,e,f必须按关键字传递
print( func2(11,99,22,d = 0,e = 55,f = 33))
print( func2(a = 11,b = 99,c = 22,d = 0,e = 55,f = 33))


# func3调用：a,b,c必须按位置传递
print( func3(111,999,222,0,555,333))
print( func3(111,999,222,d = 0,e = 555,f = 333))

 在line33后，增加一行函数调用，重新运行后出现错误提示信息

 在line38后，增加一行函数调用，重新运行后出现错误提示信息

 task2_2

list1 = [1,9,8,4]

print( sorted(list1))
print( sorted(list1,reverse = True))
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

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))

 

实验任务3

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: int 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()

 

 

实验任务4

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


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

 

 

实验任务5

def is_prime(n):
    if n <= 1:
        return False
    for i in range(2, int(n ** 0.5) + 1):
        if n % i == 0:
            return False
    return True


even_numbers = list(range(4, 21, 2))
for num in even_numbers:
    for i in range(2, num // 2 + 1):
        if is_prime(i) and is_prime(num - i):
            print(f'{num} = {i} + {num - i}')
            break

 

 

实验任务6

def encoder(text):
    encoded_text = ""
    for char in text:
        if char.isalpha():
            if char.islower():
                encoded_char = chr((ord(char) - ord('a') + 5) % 26 + ord('a'))
            else:
                encoded_char = chr((ord(char) - ord('A') + 5) % 26 + ord('A'))
        else:
            encoded_char = char
        encoded_text += encoded_char
    return encoded_text


def decoder(text):
    decoded_text = ""
    for char in text:
        if char.isalpha():
            if char.islower():
                decoded_char = chr((ord(char) - ord('a') - 5) % 26 + ord('a'))
            else:
                decoded_char = chr((ord(char) - ord('A') - 5) % 26 + ord('A'))
        else:
            decoded_char = char
        decoded_text += decoded_char
    return decoded_text


# 主体代码逻辑
text = input('输入英文文本: ')
encoded_text = encoder(text)
print('编码后的文本: ', encoded_text)
decoded_text = decoder(encoded_text)
print('对编码后的文本解码: ', decoded_text)

 

 

实验任务7

def collatz(n):
    if n % 2 == 0:
        return n // 2
    else:
        return n * 3 + 1
 
 
try:
    num = int(input("请输入一个正整数: "))
    if num <= 0:
        raise ValueError
    sequence = [num]
    while num != 1:
        num = collatz(num)
        sequence.append(num)
    print(sequence)
except ValueError:
    print("Error: must be a positive integer")
 

 

 

实验任务8

def func(n):
    if n > 0:
        return (func(n-1)+1)*2-1
    else:
        return 0
 
while True:
    x = input()
    if x == '#':
        print('计算结束')
        break
    n = int(x)
    ans = func(n)
    print(f'n = {n}, ans = {ans}')