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周二3、4节/周五3、4节/周五7、8节
4 小节, 21 道题
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本平台是《Python程序设计》课程的作业平台，也是测试平台，请同学们实名注册，并加入到本班的训练计划中来。
4 小节, 21 道题
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所有学生需要完成20道在线编程题。完成了这些题Python语法就基本没有问题了。
4 小节, 20 道题
所有学生需要完成20道在线编程题。结止日期为第8周末。共15分。
4 小节, 20 道题
本平台是《Python程序设计》课程的作业平台，也是测试平台，请同学们实名注册，并加入到本班的训练计划中来。
4 小节, 21 道题
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习题 27: 记住逻辑关系本科时数学课上学过这部分内容，所以逻辑运算符并不陌生，这些真值表也能够在看一遍的基础上理解和记忆，难度系数一颗星。习题 28: 布尔表达式练习
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">" ：大于">=" ：大于等于"<" ：小于"<=" ：小于等于"==" ：等于"!=" ：不等于
习题 29: 如果(if)people = 20cats = 30dogs = 15if people < cats:print('Too many cats! The world is doomed!')if people > cats:print("Not many cats! The world is saved!")if people < dogs:print("The world is drooled on!")if people > dogs:print("The world is dry!")dogs += 5if people >= dogs:print ("People are greater than or equal to dogs.")if people <= dogs:print ("People are less than or equal to dogs.")if people == dogs:print ("People are dogs.")
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（1） 进行逻辑判断（2） 4个空格，是作为同一段语句的判断（3） 不缩进就会报错，IndentationError: expected an indented block意思就是缩进错误（4） 可以实现（5） 会报错， SyntaxError: invalid syntax意思是变量赋值不完整。
习题 30: Else 和 Ifpeople = 30cars = 40buses = 15if cars > people:print ("We should take the cars.")elif cars < people:print ("We should not take the cars.")else:print ("We can't decide.")if buses > cars:print ("That's too many buses.")elif buses < cars:print ("Maybe we could take the buses.")else:print ("We still can't decide.")if people > buses:print ("Alright, let's just take the buses.")else:print ("Fine, let's stay home then.")
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（1） elif 等于 else if，但elif和else都是if的子块，不能单独存在，If和elif的对应关系是一对多。（2） 修改变量的大小，都可能对输入结果产生影响，具体要看变量之间的大小关系而定。
习题 32: 循环和列表the_count = [1, 2, 3, 4, 5]fruits = ['apples', 'oranges', 'pears', 'apricots']change = [1, 'pennies', 2, 'dimes', 3, 'quarters']
for number in the_count:print ("This is count %d" % number)
for fruit in fruits:print ("A fruit of type: %s" % fruit)
for i in change:print ("I got %r" % i)
elements = []
for i in range(0, 6):print ("Adding %d to the list." % i)
elements.append(i)
for i in elements:print ("Element was: %d" % i)
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（1） range函数里可以传入三个值，第一个是起始值，第二个是结束值（开区间），第三个值是步长（2） 如果不使用for循环遍历的话，那么输出elements的结果还是列表形式的。（3） 列表操作包含以下函数:1、cmp(list1, list2)：比较两个列表的元素2、len(list)：列表元素个数3、max(list)：返回列表元素最大值4、min(list)：返回列表元素最小值5、list(seq)：将元组转换为列表列表操作包含以下方法:1、list.append(obj)：在列表末尾添加新的对象2、list.count(obj)：统计某个元素在列表中出现的次数3、list.extend(seq)：在列表末尾一次性追加另一个序列中的多个值（用新列表扩展原来的列表）4、list.index(obj)：从列表中找出某个值第一个匹配项的索引位置5、list.insert(index, obj)：将对象插入列表6、list.pop(obj=list[-1])：移除列表中的一个元素（默认最后一个元素），并且返回该元素的值7、list.remove(obj)：移除列表中某个值的第一个匹配项8、list.reverse()：反向列表中元素9、list.sort([func])：对原列表进行排序
习题 33: While 循环i = 0numbers = []while i < 6:print ("At the top i is %d" % i)numbers.append(i)i = i + 1print ("Numbers now: ", numbers)print ("At the bottom i is %d" % i)print ("The numbers: ")for num in numbers:print(num)
结果：At the top i is 0Numbers now: [0]At the bottom i is 1At the top i is 1Numbers now: [0, 1]At the bottom i is 2At the top i is 2Numbers now: [0, 1, 2]At the bottom i is 3At the top i is 3Numbers now: [0, 1, 2, 3]At the bottom i is 4At the top i is 4Numbers now: [0, 1, 2, 3, 4]At the bottom i is 5At the top i is 5Numbers now: [0, 1, 2, 3, 4, 5]At the bottom i is 6The numbers:012345
（1）def fx(a):numbers = []i = 0while i < a :print ("At the top i is %d" % i)numbers.append(i)i = i + 1print ("Numbers now: ", numbers)print ("At the bottom i is %d" % i)return (numbers)print ("The numbers: ")for num in fx(6) :print (num)（3）def fx(a,b):numbers = []i = 0while i < a :print ("At the top i is %d" % i)numbers.append(i)i = i + bprint ("Numbers now: ", numbers)print ("At the bottom i is %d" % i)return (numbers)print ("The numbers: ")for num in fx(6,1) :print (num)
习题 34: 访问列表的元素color = ["red", "yellow", "green", "blue", "pink", "black", "white"]print ("1.The color at 1 is 2rd and he is", color[1])print ("2.The 3rd color is at 2 and he is", color[2])print ("3.The 1st color is at 0 and he is", color[0])print ("4.The color at 3 is 2rd and he is", color[3])print ("5.The 5th color is 4 and he is", color[4])print ("6.The color at 2 is 3rd and he is", color[2])print ("7.The 6th color is 5 and He is", color[5])print ("8.The color at 4 is 5th and he is", color[4])
结果：1.The color at 1 is 2rd and he is yellow2.The 3rd color is at 2 and he is green3.The 1st color is at 0 and he is red4.The color at 3 is 2rd and he is blue5.The 5th color is 4 and he is pink6.The color at 2 is 3rd and he is green7.The 6th color is 5 and He is black8.The color at 4 is 5th and he is pink
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