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)
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
task 2_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] 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))
line30后增加一行函数
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] 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(11,99,22,0,55,33)) print( func3(111,999,222,0,555,333)) print( func3(111,999,222,d = 0,e = 555,f = 333))
错误提示信息
line33后，增加一行函数调用
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] 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)) print( func3(a = 111,b = 999,c = 222,0,555,333))
错误提示信息
task2_2
1 list1 = [1,9,8,4] 2 3 print( sorted(list1)) 4 print( sorted(list1,reverse = True)) 5 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
1 def func(a,b,c,/,*,d,e,f): 2 return( [a,b,c,d,e,f] ) 3 4 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 :param 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()
在line22之前增加一行代码
def solve(a,b,c): ''' 求解一元二次方程，返回方程的两个根 :param 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: 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()
task 5
def is_prime(n): x = 2 m = True if n == 2: return True while n > x: if n%x == 0 and m == True: m = False else: x+=1 return m for number in range(2,21,2): for x in range(2,int(number/2)+1): y = number-x if is_prime(x) == True and is_prime(y) == True: print('{}={}+{}'.format(number,x,y)) break
task6
def encorder(text): list = [] for i in text: if 65<=ord(i)<=85 or 97<=ord(i)<=117: list.append(chr((ord(i)+5))) elif 86<=ord(i)<=90 or 118<=ord(i)<=122: list.append(chr(ord(i)-21)) else: list.append(i) return ''.join(list) def decorder(text): list = [] for i in text: if 70<=ord(i)<=90 or 102<=ord(i)<=122: list.append(chr((ord(i)-5))) elif 65<=ord(i)<=69 or 97<=ord(i)<=101: list.append(chr((ord(i)+21))) else: list.append(i) return ''.join(list) text=input('输入英文文本；') print(f'编码后的文本；{encorder(text)}') print(f'解码后的文本；{decorder(encorder(text))}')
task7
def collatz(n): if n%2 == 0: return n/2 else: return 3*n+1 try: n =int(input('Enter a positive integer:')) if n > 0: list = [] while n != 1: list.append(n) n = collatz(n) list.append(1) print(list) else: print('Error:must be a positive integer') except: print('Error:must be a positive integer')
实验总结：
1.对于try...except...的使用仍不熟练，需要加强练习
2.对于chr(),ord()的使用仍不熟练，需要加强练习
3.对于函数的编写能力有了一定的提升，希望自己能够继续努力
