Python中For循环与While 循环的使用 |
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Python中For循环与While 循环的使用
For循环在枚举中使用:Continue和Break在For循环中的使用:举例:For 循环与While 循环区别:break语句在While 循环中使用:
For循环是迭代对象元素的常用方法,具有可迭代方法的任何对象都可以在for循环中使用。python的一个独特功能是代码块不被{} 或begin,end包围。相反,python使用缩进,块内的行必须通过制表符缩进,或相对于周围的命令缩进4个空格。 For循环在枚举中使用:返回一个元组,其中包含每次迭代的计数(从默认为0开始)和迭代序列获得的值: # For在枚举中使用: # 返回一个元组,其中包含每次迭代的计数(从默认为0开始)和迭代序列获得的值: friends = ['steve', 'rachel', 'michael', 'adam', 'monica'] for index, friend in enumerate(friends): print(index,friend) Continue和Break在For循环中的使用:利用For循环:从下面文本中删除标点符号并将其转换为列表: On a dark desert highway, cool wind in my hair Warm smell of colitas, rising up through the air Up ahead in the distance, I saw a shimmering light My head grew heavy and my sight grew dim I had to stop for the night There she stood in the doorway; I heard the mission bell And I was thinking to myself, “This could be Heaven or this could be Hell” Then she lit up a candle and she showed me the way思路: 第一步:从文本中删除标点符(String中replace方法)第二步:将其转换为列表(Split函数:将String转换成list) # 利用For循环:从文本中删除标点符号并将其转换为列表:(Continue在For循环中的使用:) text='''On a dark desert highway, cool wind in my hair Warm smell of colitas, rising up through the air Up ahead in the distance, I saw a shimmering light My head grew heavy and my sight grew dim I had to stop for the night There she stood in the doorway; I heard the mission bell And I was thinking to myself, "This could be Heaven or this could be Hell" Then she lit up a candle and she showed me the way''' print(text) #第一步:从文本中删除标点符, for char in '-.,;\n"\'': text = text.replace(char,' ') print(text) #第二步:将其转换为列表 # Split converts string to list。Split函数:将String转换成list print('要将其转换为列表:',text.split(' ')[0:20]) #法一:利用空格长度=0,去除列表中空格。 # Each item in list is split on spaces # Dont want to have non words in my list for example '' # which in this case are things of zero length len('') # Making new list with no empty words in it cleaned_list = [] for word in text.split(' '): word_length = len(word) if word_length > 0: cleaned_list.append(word)#不是空格,append追加 print('利用For循环中if语句:',cleaned_list[0:20]) #法二:利用Continue: # continue语句将转到循环的下一次迭代 # continue语句用于忽略某些值,但不会中断循环 cleaned_list = [] for word in text.split(' '): if word == '': continue#如果是空格,不处理,继续for循环 cleaned_list.append(word) print('利用For循环中continue',cleaned_list[0:20]) # for中Break的使用: # break语句将完全打断循环 cleaned_list = [] for word in text.split(' '): if word == 'desert': print('I found the word I was looking for') break cleaned_list.append(word) print(cleaned_list) 举例:编写一个Python程序,使用for循环迭代整数从1到50。对于偶数的整数,将其附加到列表even_numbers;对于奇数的整数,将其附加到奇数奇数列表中。 # Making empty lists to append even and odd numbers to. even_numbers = [] odd_numbers = [] for number in range(1,51): if number%2==0: even_numbers.append(number) else: odd_numbers.append(number) print(even_numbers,"\n",odd_numbers) For 循环与While 循环区别: For 循环While 循环遍历一组对象条件为false时自动终止没有break也可以结束使用break语句才能退出循环 break语句在While 循环中使用:使用break可以完全退出循环 count = 0 while count |
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