实验4 函数与异常处理编程

print(sum)
sum = 42
print(sum)

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

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

四处sum作用域不同。第一个是内置函数名称，第二个是赋值名称，第三个是局部变量，第四个是全局变量

list1 = [1,9,8,4]

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

参数reverse的传递方式必须使用关键字传递

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))

def solve(a,b,c):
    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abc,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()

task 4

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

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

task 5

def is_prime(s):
    sum=0
    for i in range(2,s):
        if s%i==0:
            sum+=i
    ans=sum==0
    return ans

for i in range(2,21,2):
    s=[]
    for j in range(2,i):
        if is_prime(j)==True:
            s.append(j)
    for m in s:
        if (i-m)in s:
            print(f'{i}={m}+{i-m}')
            break

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)}')

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):
    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}')