如何从一个字符串中解析 N个命令来执行？"xxxcls"就执行cls,"xxxcls*********dir..."就执行cls,再执行dir等等的

cqpp 2006-08-23 10:29:53

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cqpp 2006-08-26

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没有好点的办法了吗？

tailzhou 2006-08-23

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算法的复杂度应该是 o(n*m); n是你的流的长度；m是你的命令表元素的个数；

tailzhou 2006-08-23

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那是命令解析的处理的问题了。跟是不是流以及用不用缓冲区都没什么关系；

也可以考虑用kmp;

struct instruct
{
int len; //指令的长度
char word[50]; //指令
int kmp[50]; //指令的kmp值
int idx; //模式中的当前位置;
}

struct instruction instructions[100]; 你的指令表；
int c;
while ((c=yougetchar())!=EOF)
{
for (i=0;i<100;++i)
{
//c跟instructions[i].word[idx]比较，依据结果更新idx;
//当idx==len时，找到指令，重新设置instructions数组各元素的idx
}
}

具体实现参见kmp算法；

cqpp 2006-08-23

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你怎么从缓冲区识别命令?挨个命令使用strstr?

tailzhou 2006-08-23

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为什么一定要从流里识别数据？？

先保存到缓冲区，边处理边读，不更方便么？

cqpp 2006-08-23

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关键是如何从流中识别出命令?要考虑效率

cqpp 2006-08-23

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我准备做成一张精心准备的命令表(按字典一样排好顺序),然后对单个字符来了做成状态机处理.看看如何?

tailzhou 2006-08-23

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缓冲区具体要多大,
以及什么时候再从流继续读取,
取决于你的具体的查找算法.

tailzhou 2006-08-23

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你可以用一个字符数组来做缓冲呀；

比如你的命令的最长的是10个字符；
那么你就建立一个20长度的字符数组，

流（从串口来的）的信息先到你的数组做缓冲，

数组里的数据处理掉n个(10个以上)的字符后，移动未处理的字符到数组的开头，然后在读取n个字符到数组的末尾；

cqpp 2006-08-23

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当然 ,命令表我是有,不然怎么执行命令呢?

cqpp 2006-08-23

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上面的几种都考虑过！关键我的数据来源是一个流一样的（从串口来的）。不可能每收到一个字符就去做一遍查找!

robin_yao 2006-08-23

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总要给出所有的命令字符汇总表吧
否则怎么判断哪些是命令？

chenhu_doc 2006-08-23

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把所有的命令一字符串的形式放在一个字符串数组中。

然后对给定的字符串中做匹配！

每得到一个匹配就; system("matched order");

1。考虑KMP算法匹配！
2。c中的string函数：strstr，得到匹配的位置，然后通过position排序！根据排序后的字符串数组来依次执行system命令！

3。如果追求效率，那么可以用索引来对即定的命令做初始化！

tailzhou 2006-08-23

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cls dir是你自己的自定义函数？？

如果你有自定义的函数xcls,那不是要执行xcls了？？

cqpp 2006-08-23

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没有分隔符，找到就执行！而且是自己的程序中实现

wlfc 2006-08-23

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这个软件可以完成这个功能：通用字符串表达式编译运行库FORCAL
网址：http://www4.skycn.com/soft/23045.html

tailzhou 2006-08-23

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题目描述不清；
你总要给出你的字符串的具体格式，
比如，哪些是分隔符等；

批处理命令大全 2013年11月11日总结

The C programming Language 第二版英文版內容列表 Table of Contents Preface.......................................................... Preface to the first edition..................................... Introduction..................................................... Chapter 1 - A Tutorial Introduction.............................. 1.1 Getting Started................................ 1.2 Variables and Arithmetic Expressions........... 1.3 The for statement.............................. 1.4 Symbolic Constants............................. 1.5 Character Input and Output..................... 1.5.1 File Copying.......................... 1.5.2 Character Counting.................... 1.5.3 Line Counting......................... 1.5.4 Word Counting......................... 1.6 Arrays......................................... 1.7 Functions...................................... 1.8 Arguments - Call by Value...................... 1.9 Character Arrays............................... 1.10 External Variables and Scope.................. Chapter 2 - Types, Operators and Expressions..................... 2.1 Variable Names................................. 2.2 Data Types and Sizes........................... 2.3 Constants...................................... 2.4 Declarations................................... 2.5 Arithmetic Operators........................... 2.6 Relational and Logical Operators............... 2.7 Type Conversions............................... 2.8 Increment and Decrement Operators.............. 2.9 Bitwise Operators.............................. 2.10 Assignment Operators and Expressions.......... 2.11 Conditional Expressions....................... 2.12 Precedence and Order of Evaluation............ Chapter 3 - Control Flow......................................... 3.1 Statements and Blocks.......................... 3.2 If-Else........................................ 3.3 Else-If........................................ 3.4 Switch......................................... 3.5 Loops - While and For.......................... 3.6 Loops - Do-While............................... 3.7 Break and Continue............................. 3.8 Goto and labels................................ Chapter 4 - Functions and Program Structure...................... 4.1 Basics of Functions............................ 4.2 Functions Returning Non-integers............... 4.3 External Variables............................. 4.4 Scope Rules.................................... 4.5 Header Files................................... 4.6 Static Variables................................ 4.7 Register Variables.............................. 4.8 Block Structure................................. 4.9 Initialization.................................. 4.10 Recursion...................................... 4.11 The C Preprocessor............................. 4.11.1 File Inclusion........................ 4.11.2 Macro Substitution.................... 4.11.3 Conditional Inclusion................. Chapter 5 - Pointers and Arrays.................................. 5.1 Pointers and Addresses......................... 5.2 Pointers and Function Arguments................ 5.3 Pointers and Arrays............................ 5.4 Address Arithmetic............................. 5.5 Character Pointers and Functions............... 5.6 Pointer Arrays; Pointers to Pointers........... 5.7 Multi-dimensional Arrays....................... 5.8 Initialization of Pointer Arrays............... 5.9 Pointers vs. Multi-dimensional Arrays.......... 5.10 Command-line Arguments........................ 5.11 Pointers to Functions......................... 5.12 Complicated Declarations...................... Chapter 6 - Structures........................................... 6.1 Basics of Structures........................... 6.2 Structures and Functions....................... 6.3 Arrays of Structures........................... 6.4 Pointers to Structures......................... 6.5 Self-referential Structures.................... 6.6 Table Lookup................................... 6.7 Typedef........................................ 6.8 Unions......................................... 6.9 Bit-fields..................................... Chapter 7 - Input and Output..................................... 7.1 Standard Input and Output....................... 7.2 Formatted Output - printf....................... 7.3 Variable-length Argument Lists.................. 7.4 Formatted Input - Scanf......................... 7.5 File Access..................................... 7.6 Error Handling - Stderr and Exit................ 7.7 Line Input and Output........................... 7.8 Miscellaneous Functions......................... 7.8.1 String Operations...................... 7.8.2 Character Class Testing and Conversion. 7.8.3 Ungetc................................. 7.8.4 Command Execution...................... 7.8.5 Storage Management..................... 7.8.6 Mathematical Functions................. 7.8.7 Random Number generation............... Chapter 8 - The UNIX System Interface............................ 8.1 File Descriptors............................... 8.2 Low Level I/O - Read and Write................. 8.3 Open, Creat, Close, Unlink..................... 8.4 Random Access - Lseek.......................... 8.5 Example - An implementation of Fopen and Getc.. 8.6 Example - Listing Directories.................. 8.7 Example - A Storage Allocator.................. Appendix A - Reference Manual.................................... A.1 Introduction................................... A.2 Lexical Conventions............................ A.2.1 Tokens................................ A.2.2 Comments.............................. A.2.3 Identifiers........................... A.2.4 Keywords.............................. A.2.5 Constants............................. A.2.6 String Literals....................... A.3 Syntax Notation................................ A.4 Meaning of Identifiers......................... A.4.1 Storage Class......................... A.4.2 Basic Types........................... A.4.3 Derived types......................... A.4.4 Type Qualifiers....................... A.5 Objects and Lvalues............................ A.6 Conversions.................................... A.6.1 Integral Promotion.................... A.6.2 Integral Conversions.................. A.6.3 Integer and Floating.................. A.6.4 Floating Types........................ A.6.5 Arithmetic Conversions................ A.6.6 Pointers and Integers................. A.6.7 Void.................................. A.6.8 Pointers to Void...................... A.7 Expressions.................................... A.7.1 Pointer Conversion.................... A.7.2 Primary Expressions................... A.7.3 Postfix Expressions................... A.7.4 Unary Operators....................... A.7.5 Casts................................. A.7.6 Multiplicative Operators.............. A.7.7 Additive Operators.................... A.7.8 Shift Operators....................... A.7.9 Relational Operators.................. A.7.10 Equality Operators................... A.7.11 Bitwise AND Operator................. A.7.12 Bitwise Exclusive OR Operator........ A.7.13 Bitwise Inclusive OR Operator........ A.7.14 Logical AND Operator................. A.7.15 Logical OR Operator.................. A.7.16 Conditional Operator................. A.7.17 Assignment Expressions............... A.7.18 Comma Operator.......................... A.7.19 Constant Expressions.................... A.8 Declarations..................................... A.8.1 Storage Class Specifiers................. A.8.2 Type Specifiers.......................... A.8.3 Structure and Union Declarations......... A.8.4 Enumerations............................. A.8.5 Declarators.............................. A.8.6 Meaning of Declarators................... A.8.7 Initialization........................... A.8.8 Type names............................... A.8.9 Typedef.................................. A.8.10 Type Equivalence........................ A.9 Statements....................................... A.9.1 Labeled Statements....................... A.9.2 Expression Statement..................... A.9.3 Compound Statement....................... A.9.4 Selection Statements..................... A.9.5 Iteration Statements..................... A.9.6 Jump statements.......................... A.10 External Declarations........................... A.10.1 Function Definitions.................... A.10.2 External Declarations................... A.11 Scope and Linkage............................... A.11.1 Lexical Scope........................... A.11.2 Linkage................................. A.12 Preprocessing................................... A.12.1 Trigraph Sequences...................... A.12.2 Line Splicing........................... A.12.3 Macro Definition and Expansion.......... A.12.4 File Inclusion.......................... A.12.5 Conditional Compilation................. A.12.6 Line Control............................ A.12.7 Error Generation........................ A.12.8 Pragmas................................. A.12.9 Null directive.......................... A.12.10 Predefined names....................... A.13 Grammar......................................... Appendix B - Standard Library.................................... B.1.1 File Operations................................ B.1.2 Formatted Output......................... B.1.3 Formatted Input.......................... B.1.4 Character Input and Output Functions..... B.1.5 Direct Input and Output Functions........ B.1.6 File Positioning Functions............... B.1.7 Error Functions.......................... B.2 Character Class Tests: ................. B.3 String Functions: ..................... B.4 Mathematical Functions: ................. B.5 Utility Functions: ....................

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