三元操作符
语法 : x if 条件 else y
示例
small = x if < x else y
断言(assert)
当这个关键字后边的条件为假的时候,程序自动崩溃并抛出AssertionError的异常。一般用于检查。
示例
assert 3>4
While
语法
while 条件:
循环体
for循环
语法
for 目标 in 表达式
循环体
range()
语法
range([strart,] stop[,step=1])
1.表示这个BIF有三个参数,其中用中括号括起来的两个表示这两个参数是可选的。
2.step = 1 表示第三个参数的默认值是1.
3. range这个BIF的作用是生成一个从start参数的值开始到stop参数的值结束的数字序列。
for i in range(5): print(i)输出为 0 1 2 3 4
for i in range(2,9): print(i)输出为 2 3 4 5 6 7 8
for i in range(1,10,2): print(i)输出为 1 3 5 7 9
break 和 continue
break 跳出循环
bingo = '我爱马里奥' answer = input('请输入小甲鱼最想听的一句话:') while True: if answer == bingo: break answer = input('抱歉,错了,请重新输入(答案正确才能退出游戏):') print('哎哟,帅哦~') print('您真是马里奥肚子里的蛔虫啊^_^')
continue 终止本轮循环 开始下一轮循环
for i in range(10): if i%2 != 0: print(i) continue i += 2 print(i)
列表(打了激素的数组)
1.创建一个普通列表
member = ["1","2","3"] member
2.创建一个混合列表
mix = [1,"文字",3.14,[1,2,3]]
3.创建一个空列表
empty = []
向列表添加元素
append()
无法添加 这样的 member.append("5","6")
member = ["1","2","3"] member.append("4") member
extend()
用一个列表扩张另一个列表 member.extend(["5","6"])
member = ["1","2","3"] member.extend(["5","6"]) member
insert()
两个参数 第一个参数代表在列表中的位置 第二个参数表示在第一个参数的位置插入一个元素(就是元素 名称)
member = ["1","2","3"] member.insert(0,"0") member
调换元素位置
member = ["4","2","3","1"] temp = member[0] member[0] = member[3] member[3] = temp member
从列表中删除元素
1.remove() 参数为元素名字
member = ["4","2","3","1"] member.remove("2")
如果没有此元素 则报错
2. del 语句
member = ["4","2","3","1"] del member[1] member
如果 del member 则删除整个列表
member = ["4","2","3","1"] del member member
3. pop() 去除最后一个元素 并返回(可赋值)
member = ["4","2","3","1"] member.pop()
可加参数(位置号)
member = ["4","2","3","1"] member.pop(1) member4.分片(可赋值)
member = ["4","2","3","1"] member[1:3] member
返回 2 3
可简写 冒号前边不加数字 表示从最前边开始 同理 后边不加数字 表示取到末尾 两边都不写 拷贝整个列表(可赋值)
member = ["4","2","3","1","5","6"] member[:3] member[1:]
列表常用操作符
1. 比较
比较数组第一项
2. + 号 必须同类型
3. *号 复制列表3次 例
list = [123,456] list*3
4. = 赋值操作 可与*复合
list = [123,456] list *= 3 list
5.成员关系操作符
返回 true 或者 false
list = [123,456] "123" in list "123" not in list "文字" in list "文字" not in list
判断列表中列表的元素
list = [012,["文字","文字1"],4566] "文字" in list[1]
访问列表中列表的值
list = [012,["文字","文字1"],4566] list[1][1]
列表类型的内置函数BIF
dir(list)
1.count 计算参数在列表中出现的次数
list[123,123,456,789,8,,78,87,8745,64678,74,685,1321654,8,74,564,89,7,98,74,454,654,8,7,1] list.count(123)
2.index 返回列表中的位置,三个参数(元素,起始,结束)
list[123,123,456,789,8,,78,87,8745,64678,74,685,1321654,8,74,564,89,7,98,74,454,654,8,7,1] list.index(123)
list[123,123,456,789,8,,78,87,8745,64678,74,685,1321654,8,74,564,89,7,98,74,454,654,8,7,1] list.count(123,0,6)
3.reverse 将整个列表翻转
list[123,123,456,789,8,,78,87,8745,64678,74,685,1321654,8,74,564,89,7,98,74,454,654,8,7,1] list.reverse() list
4 sort 用于指定对列表排序 默认从小到大
list = [1,3,2,5,8,78,46,4,54,531,3,48,] list.sort() list
从大到小排序
list = [1,3,2,5,8,78,46,4,54,531,3,48,] list.sort(reverse.true) list