实验任务4

任务一

代码：

print(sum)
sum = 42
print(sum)

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

sum = inc(7) + inc(7)
print(sum)

运行结果：

问题：

不是，line1sum的作用域为line1到line2，line3的sum等同于line1的；line7的为line5至line7，line11的为line5至line11

 

 

任务二

代码：

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

运行结果：

问题：

是

 

任务三

代码：

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()

运行截图：

 

 

实验四

代码：

def list_genetator(q,z,b = 1):
     lst = []
     while q <= z:
         if q <= z+1:
             lst.append(q)
             q = q+b
         else:
             break
 
     return lst
 
list1 = list_genetator(-5,5)
print(list1)
 
list2 = list_genetator(-5,5,2)
print(list2)
 
list3 = list_genetator(1,5,0.5)
print(list3)

运行截图：

   

 

 

任务五

代码：

def is_prime(n):
    if n > 1:
        if n%2 > 0:
            return True
        elif n == 2:
            return True
        else:
            return False
    else:
        return False
 
s = [i for i in range(1,21)]
s_1 = []
s_2 = []
s_3 = {}
for j in s:
    if is_prime(j) == True:
        s_1.append(j)
for y in s:
     if y > 2 and y%2 == 0:
         s_2.append(y)
for i in range(len(s_2)):
     for z in s_1:
         for q in s_1:
             if z + q == s_2[i]:
                 s_3.setdefault(s_2[i],(z,q))
for key,value in s_3.items():
    a = value[0]
    b = value[1]
print(f'{key} = {a}+{b}')

运行截图：

实验六

代码：

list_s=['a','b','c','d','e','f','g','h','i','j','k',
        'l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']
list_b=['A','B','C','D','E','F','G','H','I','J','K',
        'L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z']
def encoder(x):
    re=[]
    for i in str(x):
        if i in list_s:
            a=list_s.index(i)
            if a<=20:
                i=list_s[a+5]
                re.append(i)
            else:
                i=list_s[a+5-26]
                re.append(i)
        elif i in list_b:
            a=list_b.index(i)
            if a<=20:
                i=list_b[a+5]
                re.append(i)
            else:
                i=list_b[a+5-26]
                re.append(i)
        else:
            re.append(i)
    re=''.join(re)
    return re
def decoder(x):
    re=[]
    for i in str(x):
        if i in list_s:
            a=list_s.index(i)
            if a>=5:
                i=list_s[a-5]
                re.append(i)
            else:
                i=list_s[a+26-5]
                re.append(i)
        elif i in list_b:
            a=list_b.index(i)
            if a>=5:
                i=list_b[a-5]
                re.append(i)
            else:
                i=list_b[a+26-5]
                re.append(i)
        else:
            re.append(i)
    re=''.join(re)
    return re

x=input('输入英文文本:')
print(f'编码后的文本:{encoder(x)}')
y=encoder(x)
print(f'对编码后的文本解码:{decoder(y)}')

截图：

 

 

 

实验七

代码：

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

截图：

 

 

实验八

代码：

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