python元组
1.定义
在一堆小括号中的数据，不同元素使用逗号隔开，列表可变，元组不可变。
tuple_a = ("nginx","httpd","tomcat")
print(type(tuple_a))
# 元组数据类型可以任意
tuple_b = (10,3.14,"nginx",["redis","monogodb"],("mysql","oracle"))
print(type(tuple_b))
# 单个元素的元组
tuple_c = ("nginx",) # 注意元素后面的逗号，不可少
print(type(tuple_c))
2.元组的常规操作
len() in , not in
2.1 索引
tuple_a = ("nginx","httpd","iis")
print(tuple_a[1])
tuple_a[1] = "tomcat" # 错误：元组是不可变的
# 元组
data = ("nginx","httpd",["redis","mongodb"])
data[-1][0] = "memcached"
print(data)