二十五、名企片爬虫面试题
1. 简述一次完整的 http 的通信过程、常用的响应状态码、http 的无状态性、Cookies
等这些概念(2018-5-11-xhq)
一、http 过程
HTTP 通信机制是在一次完整的 HTTP 通信过程中，Web 浏览器与 Web 服务器之间将完成下
列 7 个步骤：
1. 建立 TCP 连接
在 HTTP 工作开始之前，Web 浏览器首先要通过网络与 Web 服务器建立连接，该连接是通过 TCP
来完成的，该协议与 IP 协议共同构建 Internet，即著名的 TCP/IP 协议族，因此 Internet 又被称作是
TCP/IP 网络。HTTP 是比 TCP 更高层次的应用层协议，根据规则，只有低层协议建立之后才能进行更
高层协议的连接，因此，首先要建立 TCP 连接，一般 TCP 连接的端口号是 80。
2. Web 浏览器向 Web 服务器发送请求命令
2023-08-18 16:20:21
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Tcl 语法
Tcl是一种很通用的脚本语言，它几乎在所有的平台上都可以释运行，其强大的功能和简单精妙的语法会使你感到由衷的喜悦，这片文章对 Tcl有很好的描述和说明。极具可读性，我并不是原封不动的翻译而是加上了一些自己的体会和例子，如有错误请指正。如果你看起来很吃力，那是因为 Tcl与一般的语言有一些不同之处，刚开始可能有一些不理解，但很快就会掌握的。请坚持一下,我能坚持写完，你至少也应该坚持读一遍吧！
2023-01-09 09:57:43
98KB
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VIVADO经常使用TCL脚本对FPGA进行调试,通过JTAG转AXI对内部模块进行控制,但是TCL语言书籍比较少,这边是一个英文的TCL语言学习书籍.
第 1 章. TCL基本知识................................................................................................................1
1.1 什么是TCL..............................................................................................................................1
1.2 TCL自学工具...........................................................................................................................1
1.3 TCL软件包..............................................................................................................................2
1.4 TCL命令格式...........................................................................................................................2
1.5 TCL脚本文件和SOURCE 命令..................................................................................................3
1.6 可执行脚本文件(EXECUTABLE FILE)...........................................................................................3
1.7 获得帮助.................................................................................................................................4
1.7.1 Windows系统.............................................................................................................4
1.7.2 Unix系统......................................................................................................................4
第 2 章. 输出、赋值与替换........................................................................................................5
2.1 PUTS.........................................................................................................................................5
2.2 SET & UNSET..............................................................................................................................5
2.3 替换........................................................................................................................................6
2.3.1 $...................................................................................................................................6
2.3.2 []..................................................................................................................................6
2.3.3 " " 和{}..........................................................................................................................6
2.3.4 \...................................................................................................................................7
第 3 章. 数学表达式与EXPR命令..............................................................................................8
3.1 数学和逻辑运算符..................................................................................................................8
3.2 数学函数.................................................................................................................................8
3.3 数学运算举例.........................................................................................................................9
3.4 INCR命令................................................................................................................................9
第 4 章. 字符串........................................................................................................................10
4.1 基本命令集...........................................................................................................................10
4.2 APPEND命令..........................................................................................................................10
4.3 FORMAT命令..........................................................................................................................10
4.3.1 format命令说明......................................................................................................10
4.3.2 format举例..............................................................................................................11
4.4 SCAN命令.............................................................................................................................12
4.5 BINARY命令...........................................................................................................................13
4.6 SUBST命令..............................................................................................................................14
4.7 STRING 命令...........................................................................................................................15
4.7.1 string 命令列表.........................................................................................................15
4.7.2 字符串比较................................................................................................................16
4.7.3 string match字符串匹配.........................................................................................16
4.7.4 字符串替换................................................................................................................18
4.7.5 字符类别(class)测试.................................................................................................18
4.7.6 字符串映射................................................................................................................19
第 5 章. TCL列表操作..............................................................................................................20
5.1 列表命令集...........................................................................................................................20
5.2 LIST命令.................................................................................................................................20
5.3 CONCAT命令.........................................................................................................................21
5.4 LAPPEND命令........................................................................................................................21
5.5 LLENGTH 命令.........................................................................................................................22
5.6 LINDEX命令............................................................................................................................22
5.7 LRANGE命令..........................................................................................................................22
5.8 LINSERT 和LREPLACE命令........................................................................................................22
5.9 LSEARCH命令.........................................................................................................................23
5.10 LSORT命令.............................................................................................................................24
5.11 JOIN与SPLIT命令...................................................................................................................24
5.12 FOREACH控制结构................................................................................................................27
第 6 章. 数组............................................................................................................................28
6.1 数组的定义与格式................................................................................................................28
6.2 数组变量...............................................................................................................................29
6.3 多维数组...............................................................................................................................29
6.4 数组操作命令.......................................................................................................................30
6.4.1 array get命令.........................................................................................................30
6.4.2 array names命令....................................................................................................30
6.4.3 遍历数组...................................................................................................................31
6.4.4 用数组定义结构........................................................................................................31
第 7 章. 控制结构命令.............................................................................................................32
7.1 IF/ELSE命令............................................................................................................................32
7.2 FOR命令................................................................................................................................33
7.3 WHILE命令.............................................................................................................................33
7.4 BREAK 与 CONTINUE命令........................................................................................................34
7.5 SWITCH命令...........................................................................................................................34
7.6 CATCH 命令...........................................................................................................................35
7.7 ERROR命令............................................................................................................................36
7.8 RETURN 命令...........................................................................................................................37
7.9 EXIT命令................................................................................................................................37
第 8 章. 过程与作用域.............................................................................................................38
8.1 PROC—过程定义命令...........................................................................................................38
8.2 作用域...................................................................................................................................40
8.2.1 过程的作用域............................................................................................................40
8.2.2 变量的作用域............................................................................................................40
8.3 UPVAR命令............................................................................................................................42
8.4 RENAME命令.........................................................................................................................44
8.5 特殊变量...............................................................................................................................45
8.5.1 命令行参数................................................................................................................45
8.5.2 env--环境变量数组...................................................................................................45
8.6 EVAL命令..............................................................................................................................46
8.7 UPLEVEL命令..........................................................................................................................48
第 9 章. 正则表达式（REGULAR EXPRESSIONS）...................................................................49
9.1 REGEXP命令..........................................................................................................................49
9.2 REGSUB命令...........................................................................................................................51
9.3 正则表达式的语法................................................................................................................52
9.3.1 分支(branch)和原子(atom)....................................................................................52
9.3.2 基本语法...................................................................................................................52
9.3.2.1 匹配字符........................................................................................................................................52
9.3.2.2 限定匹配........................................................................................................................................53
9.3.2.3 方括号表达式与字符集.................................................................................................................53
9.3.2.4 匹配分支........................................................................................................................................54
9.3.2.5 量词（Qulifier）...........................................................................................................................54
9.3.2.6 子模式与匹配报告捕获.................................................................................................................55
9.3.2.7 反斜杠引用....................................................................................................................................56
9.3.2.8 匹配优先级....................................................................................................................................56
9.3.3 高级正则表达式（AREs）.........................................................................................57
9.3.3.1 反斜杠换码(escape)序列............................................................................................................57
9.3.3.2 归整元素(collating element).....................................................................................................57
9.3.3.3 等价类(equivalence class)........................................................................................................58
9.3.3.4 字符类(character class).............................................................................................................58
9.3.3.5 非贪婪量词....................................................................................................................................59
9.3.3.6 约束量词........................................................................................................................................59
9.3.3.7 回退引用........................................................................................................................................59
9.3.3.8 前瞻(lookahead).........................................................................................................................60
9.3.3.9 换行符敏感的匹配.........................................................................................................................60
9.3.3.10 嵌入式选项...............................................................................................................................60
9.3.3.11 扩展语法...................................................................................................................................60
9.3.4 语法小结...................................................................................................................60
9.3.5 其它支持正则表达式的命令......................................................................................60
第 10 章. 名字空间.................................................................................................................62
10.1 创建名字空间...................................................................................................................62
10.2 用::限定符来使用变量和过程...........................................................................................62
10.3 名字空间的变量...............................................................................................................63
10.4 过程的进口与出口............................................................................................................64
10.5 内省(INTROSPECTION).........................................................................................................65
10.6 名字空间命令集...............................................................................................................65
第 11 章. 跟踪与调试.............................................................................................................67
11.1 CLOCK命令...........................................................................................................................67
11.1.1 clock clicks命令......................................................................................................67
11.1.2 clock seconds命令................................................................................................67
11.1.3 clock format命令...................................................................................................68
11.1.4 clock scan命令.......................................................................................................70
11.2 INFO 命令...............................................................................................................................71
11.2.1 info level..................................................................................................................72
11.2.2 info exists.................................................................................................................72
11.3 TRACE命令............................................................................................................................73
11.3.1 trace variable.........................................................................................................73
11.3.2 trace vdelete..........................................................................................................75
11.3.3 trace vinfo...............................................................................................................75
第 12 章. 脚本库与软件包......................................................................................................76
12.1 声明和使用软件包............................................................................................................76
12.1.1 软件包定位................................................................................................................76
12.1.2 声明软件包命令........................................................................................................76
12.1.3 加载软件包命令........................................................................................................76
12.1.4 自动加载与软件包索引.............................................................................................77
12.1.5 用链接库提供软件包.................................................................................................79
12.2 PACKAGE命令集...................................................................................................................80
12.3 小结..................................................................................................................................80
第 13 章. 文件操作与程序调用...............................................................................................81
13.1 文件操作...........................................................................................................................81
13.1.1 文件I/O....................................................................................................................81
13.1.2 文件系统信息命令.....................................................................................................82
13.1.2.1 glob命令.................................................................................................................................83
13.1.2.2 file命令集.................................................................................................................................83
13.2 程序调用...........................................................................................................................85
13.2.1 用open命令打开一个进程管道..............................................................................85
13.2.2 用exec命令调用程序..............................................................................................87
13.2.3 pid命令....................................................................................................................88
第 14 章. 套接字与事件驱动编程简介....................................................................................89
14.1 套接字编程.......................................................................................................................89
14.1.1 socket命令..............................................................................................................89
14.1.1.1 Client端socket命令..............................................................................................................89
14.1.1.2 Server端socket命令选项......................................................................................................90
14.1.2 用fconfigure配置套接字........................................................................................90
14.1.3 C/S编程举例............................................................................................................90
14.2 事件驱动编程...................................................................................................................93
14.2.1 after命令.................................................................................................................93
14.2.2 fileevent命令..........................................................................................................96
14.2.3 vwait命令................................................................................................................96
14.2.4 fconfigure命令.......................................................................................................97
14.2.4.1 fconfigure语法.......................................................................................................................97
14.2.4.2 非阻塞I/O................................................................................................................................98
14.2.4.3 缓冲..........................................................................................................................................98
2023-01-06 16:54:44
2.43MB
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FPGA资料
该脚本可以使用运行
将design.sv，fhw.sv，timing.tcl和run_fpga.tcl复制到新文件夹
现在运行quartus_sh -t run_fpga.tcl -project（design_name）-board sockit
design_name是不带.sv扩展名的Verilog设计的名称。 Tuples.sv编译为
quartus_sh -t run_fpga.tcl-项目元组-board sockit
还显示使用的资源以获取使用的详细资源，请检查output_files /（设计名称）.fit.summary
要获取fmax值，请使用quartus_sta -t Timing.tcl（design_name）
重新编译新的Verilog文件
替换项目中的verilog文件
quartus_sh -t recompile.tcl（设计名称）
2023-01-04 11:40:06
3KB
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C++编程嵌入Tcl脚本应用程序中经常要进行输入输出重定向处理
网上很难找到完整编程实例,本Demo在tcl8.4.20上调式OK
2022-09-27 17:23:14
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推荐，TCL教程（中文）。里面包含了TCL语法，置换（substitution）、变量、表达式、List、控制流、过程（procedure）、字符串操作、文件访问、错误和异常、深入TCL大专题，还有很多细分的专题，推荐使用。
2022-07-23 22:39:47
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系统学习TCL脚本入门教程 系统学习TCL脚本入门教程 系统学习TCL脚本入门教程 系统学习TCL脚本入门教程 系统学习TCL脚本入门教程
2022-05-02 16:39:58
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