实验4

实验Task1 

print(sum)
sum=42
print(sum)

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

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

不是。

line1：全局作用域

line3：全局作用域

line7：局部作用域

line11：全局作用域

实验task2-1

def func1(a,b,c,d,e,f):
    return[a,b,c,d,e,f]
def func2(a,b,c,*,d,e,f):
    return[a,b,c,d,e,f]
def func3(a,b,c,/,d,e,f):
    return[a,b,c,d,e,f]
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))

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))

print(func2(111,999,222,0,555,333))
print(func3(111,999,222,d=0,e=555,f=333))

实验task2-2

list1=[1,9,8,4]

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

Python内置函数sorted()中，参数reverse的传递方式必须使用关键字传递。

实验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))

task3

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
19 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()

加入一行代码后 重新运算，函数solve()的说明信息（line3-5）被打印出来了，如图。

task4

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

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task5

def is_prime(x):
    a=0
    for i in range(2,x):
        if x%i==0:
            a+=1
        else:
            a+=0
    if a==0:
        return True
    else:
        return False

list1=[]
for i in range(2,21):
    if is_prime(i)== True:
        list1.append(i)
for i in range(4,21,2):
    for j in list1:
        if is_prime(i-j)==True:
            print("{}={}+{}".format(i,j,i-j))
            break

实验task6

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)}')

 实验Task7

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))

 Task8

def func(n):
    result = 1
    for i in range(n):
        result *= 2
    return result-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}')