实验4 函数与异常处理编程
实验任务1
print(sum) sum = 42 print(sum) def inc(n): sum = n+1 print(sum) return sum sum = inc(7) + inc(7) print(sum)
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答: 不是,
第一行中的"sum"是一个未定义的变量,第二行中"sum"的作用域是整个程序的全局作用域,在函数定义中的"sum"的作用域是函数"inc"的局部作用域,在最后一行中的"sum"的作用域是全局作用域。
实验任务2
task2_2
list1 = [1, 9, 8, 4] print(sorted(list1)) print(sorted(list1, reverse=True)) print(sorted(list1, True))
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答:python内置函数sorted()中,参数reverse的传递方式是否必须使用关键字
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))
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实验任务3
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()
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实验任务4
def list_generator(a,b,c = 1): i = a lst = [] while a <= i <= b: lst.append(i) i += c return lst list1 = list_generator(-5, 5) print(list1) list2 = list_generator(-5, 5, 2) print(list2) list3 = list_generator(1, 5, 0.5) print(list3)
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实验任务5
def is_prime(n): import math m = 0 for i in range(2, int(math.sqrt(n)) + 1): if n % i == 0: m += 1 else: m += 0 if m != 0: result = False else: result = True return result for i in range(4,21,2): for j in range(2,i): if is_prime(j) == True: k = i - j if is_prime(k) == True: print(f'{i} = {j} + {k}') break
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实验任务6
def encoder(text): text1 = '' for i in text: if 'a' <= i <= 'z': c = 97 + (ord(i) + 5 - 97) % 26 text1 += chr(c) elif 'A' <= i <= 'Z': c = 65 + (ord(i) + 5 - 65) % 26 text1 += chr(c) else: text1 += i return text1 def decoder(text): text1 = '' for i in text: if 'a' <= i <= 'z': c = 97 + (ord(i) - 5 - 97) % 26 text1 += chr(c) elif 'A' <= i <= 'Z': c = 65 + (ord(i) - 5 - 65) % 26 text1 += chr(c) else: text1 += i return text1 text = input('输入英文文本: ') encoded_text = encoder(text) print('编码后的文本: ', encoded_text) decoded_text = decoder(encoded_text) print('对编码后的文本解码: ', decoded_text)
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实验任务7
def collatz(n): lst = [] lst.append(n) while n != 1: if n %2 == 0: n = n/2 lst.append(int(n)) else: n = n*3 +1 lst.append(int(n)) return lst try: n = int(input('Enter a positive integer:')) if n <= 0: raise ValueError except ValueError: print('Error: must be a positive integer') else: print(collatz(n))
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实验任务8
def func(n): if n == 0: return 0 else: return 2*func(n-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}')
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