Learn The First Day OF Operation Notes…

#MySQL for Python(MySQLdb) Note #切记不要在python中创建表,只做增删改查即可. #步骤:(0)引用库 -->(1)创建连接 -->(2)创建游标 -->(3)选择数据库 -->(4)执行语句 -->(5)关闭连接 #(0)引用库 import MySQLdb #(1)创建连接 con = MySQLdb.connect(user = ",host = "127.0.0.1") #(2)创建游标 cur = c…

Python Function Note #汉诺塔问题Python实现 def my_move(n, a, b, c): if n == 1: print(a + ' --> ' + c) else: my_move(n-1, a, c, b)#将前n-1个盘子从a放到b my_move(1, a, b, c)#将最下面的盘子从a放到c my_move(n-1, b, a, c)#将b上的n-1个盘子放到c上 return #杨辉三角Python实现 def my_triangles(max):…

上下文管理器(context manager)是Python2.5开始支持的一种语法,用于规定某个对象的使用范围.一旦对象进入或者离开该使用范围,会有特殊操作被调用 (比如为对象分配或者释放内存).它的语法形式是with-as- 关闭文件 我们会进行这样的操作:打开文件,读写,关闭文件.程序员经常会忘记关闭文件.上下文管理器可以在不需要文件的时候,自动关闭文件. f = open("new.txt", "w") print(f.closed) # whether t…

1. Translating Java Classes to Scala Classes Example 1: # a class declaration in Java public class Book{} # Scala equivalent of a class declaration class Book Example 2: # a Java class with a Construtor public class Book{ private final int isbn; priv…

1. Unified Type System Scala has a unified type system, enclosed by the type Any at the top of the hierarchy and the type Nothing at the bottom of the hierarchy. All Scala types inherit from Any. # Using Any, Book extends AnyRef, and x is an Int that…

A trait provides code reusability in Scala by encapsulating method and state and then offing possibility of mixing them into classes thus allowing code reuse. #define Trait Gliding scala> trait Gliding{ | def gliding(){ println("gliding")} |…

Scala's object-oriented collections support mutable and immutable type hierarchies. Also support functional higher-order operations such as map, filter, and reduce that let you use expression-oriented programming in collections. Higher-order operatio…

The basic functional cornerstones of Scala: immutable data types, passing of functions as parameters and pattern matching. 1. Basic Pattern Matching In Scala, your cases can include types, wildcards, sequences, regular expressions, and so forth. scal…

1. Functional programming treats computation as the evaluation of mathematical and avoids state and mutable data. Scala encourages an expression-oriented programming(EOP) 1) In expression-oriented programming every statement is an expression. A state…