• 名称
• 现实模型

• 现实模型:交通:

C:面对过程,面对硬件;
人用脚走路
优点:极端的路况,比如爬山,就只能自己"因地制宜"
缺点:大部分普通的路况,有时路面难免泥泞.就效率比较低

"这条路是什么路面(面对硬件)?"
"我该换什么样的鞋子来走这段路"
"爬山是吧?那好,我在包里掏个"工具"就上!"
"哎哟,这泥地把我的鞋弄得好脏(内存管理)"

Java:面对对象:虚拟机:
自己的车;雇佣司机
优点:沥青路,水泥地都不用自己亲自用脚去走.路面泥泞,也不用脏了自己的鞋.
缺点:不适应极端路况

"开车?我打个电话给司机(面对对象)"
"泥地?沙子多?没关系,我坐在车上呢(虚拟机)"
"轮胎脏了?车脏了?没关系,定期去洗车店就行了(内存管理)"

PHP:解释型语言:边解释边运行;在web上运行:
uber滴滴叫车,有需求的时候才需要车
优点:更加随心所欲
缺点:

"不用等了,直接把我载到山脚下,剩下的艰难路况我自己来.""见招拆招"(边解释边运行)"

• 名称&源头

C:

CSAPP

鞋子

Java:

time:

in June 1991

设计初衷:

• Java was originally designed for interactive(交互式) television, but it was too advanced for the digital cable television industry at the time.
• specifically designed to have as few implementation dependencies as possible.
• It is intended to let application developers** "write once, run anywhere" **(WORA)

特点:

general-purpose(通用性) :

• concurrent(并发)
• class-based
• object-oriented

程序员用C走路走了10几年路,觉得脚有点痛.有时候面对各种路况(不同的硬件基础)觉得有点烦了,走平地呢,我就要换对轻便的鞋.走泥地呢,我就要换对工地靴.这个时候就想:怎么样使得自己和别人更方便呢(general-purpose通用性),总不能每次上路都要带几对鞋子吧?
怎么将走路的人从这些多变的路况隔离出来呢?
好吧,设计一部车出来,这部车还是部越野车(虚拟机),适应各种路况(write once, run anywhere).

越野车

Php:

time:

1994

设计初衷:

designed forweb development but also used as a general-purpose programming language.

发展:

he PHP reference implementation is now produced by The PHP Group.(人多力量大)

更名历程:

PHP originally stood for Personal Home Page,but it now stands for the recursive backronym PHP: Hypertext Preprocessor

特点:

• be embedded into HTML code(嵌入)
• can be used in combination with various web template systems, web content management system and web frameworks.
• 边解释边运行
• any type of data, including images, with the generated web page
• PHP code may also be executed with a command-line interface (CLI)命令行 and can be used to implement standalone graphical (图形化)applications.

有时不仅仅是开车啊,我还要有点娱乐元素.那我原来的都是一部部整体的越野车(虚拟机),我想表演三轮车杂技,那我还要把车子的轮胎的一部分拆下来呢?
不一定每个人的需求就都是要开车啊,能不能按个人的需求个人去组装呢?更何况,网络发展了,把全部人都连接起来了.

那..搞个3d打印机(HTML)吧,世界各地的人你想玩啥,就玩啥...你想弄个表演杂技的小轮子车吧,那好,你弄..只要你在你家弄个3d打印机(html).

3D打印机

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