实验四

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、3、11是全局作用域，line7是函数作用域。

TASK2

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；也支持关键字传递
    '''
 
    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字传递
    '''
 
    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构成的列表
    /前面的的参数只能按位置传递
    '''
    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(func3(111,999,222,0,555,333))
print(func3(111,999,222,d=0,e=555,f=333))

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

 

 

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

 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


while True:
    try:
        a, b, c = eval(input('Enter eqution coefficient: '))
        if a == 0:
            raise
    except:
        print('invalid input, or, a is zero')
        break
    else:
        root1, root2 = solve(a, b, c)
        print(f'root1 = {root1:.2f}, root2 = {root2:.2f}')
        print()

 TASK4

 

def list_generator(a, b, c=1):
    l = [a]
    while True:
        if c == None:
            a += 1
            l.append(a)
            if a == b:
                break
        else:
            a += c
            l.append(a)
            if a == b:
                break
    return l


list1 = list_generator(-5, 5)
print(list1)

list2 = list_generator(-5, 5, 2)
print(list2)

list3 = list_generator(1, 5, 0.5)
print(list3)

 TASK5

 

from math import sqrt


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


def gd(x):
    for i in range(2, x):
        if is_prime(i):
            if is_prime(x - i):
                print(x, '=', i, '+', x - i)
                return True
    return False


i = 4
while (gd(i) and i < 20):
    i += 2

 TASK6

 

def encoder(s):
    s=list(s)
    for i in range(len(s)):
        if s[i].isalpha():
            if 'a'<=s[i].lower()<'v':
                s[i]=chr(ord(s[i])+5)
            else:
                s[i]=chr(ord(s[i])-21)
        else:
            s[i]=s[i]
    s=''.join(s)
    return s
def decoder(s):
    s=list(s)
    for i in range(len(s)):
        if s[i].isalpha():
            if 'a'<=s[i].lower()<='e':
                s[i]=chr(ord(s[i])+21)
            elif 'e'<s[i].lower()<='z':
                s[i]=chr(ord(s[i])-5)
        else:
            s[i]=s[i]
    s=''.join(s)
    return s
s=input('输入英文文本: ')
print(f'编码后的文本:{encoder(s)}')
print(f'对编码后的文本解码:{decoder(encoder(s))}')

 TASK7

 

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