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  • Unintentional concatenation in Bison/Yacc grammar.

    - by troutwine
    I am experimenting with lex and yacc and have run into a strange issue, but I think it would be best to show you my code before detailing the issue. This is my lexer: %{ #include <stdlib.h> #include <string.h> #include "y.tab.h" void yyerror(char *); %} %% [a-zA-Z]+ { yylval.strV = yytext; return ID; } [0-9]+ { yylval.intV = atoi(yytext); return INTEGER; } [\n] { return *yytext; } [ \t] ; . yyerror("invalid character"); %% int yywrap(void) { return 1; } This is my parser: %{ #include <stdio.h> int yydebug=1; void prompt(); void yyerror(char *); int yylex(void); %} %union { int intV; char *strV; } %token INTEGER ID %% program: program statement EOF { prompt(); } | program EOF { prompt(); } | { prompt(); } ; args: /* empty */ | args ID { printf(":%s ", $<strV>2); } ; statement: ID args { printf("%s", $<strV>1); } | INTEGER { printf("%d", $<intV>1); } ; EOF: '\n' %% void yyerror(char *s) { fprintf(stderr, "%s\n", s); } void prompt() { printf("> "); } int main(void) { yyparse(); return 0; } A very simple language, consisting of no more than strings and integer and a basic REPL. Now, you'll note in the parser that args are output with a leading colon, the intention being that, when combined with the first pattern of the rule of the statement the interaction with the REPL would look something like this: > aaa aa a :aa :a aaa> However, the interaction is this: > aaa aa a :aa :a aaa aa aa > Why does the token ID in the following rule statement: ID args { printf("%s", $<strV>1); } | INTEGER { printf("%d", $<intV>1); } ; have the semantic value of the total input string, newline included? How can my grammar be reworked so that the interaction I intended?

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  • How to fix a warning message associated with strlen() used in Yacc?

    - by user547894
    Hello! Please i need your help. Basically, I am facing this warning message upon compiling with gcc, and am not able to deduce the error: Here are the details: The warning message i am receiving is literrally as follows: y.tab.c: In function ‘yyparse’: y.tab.c:1317 warning: incompatible implicit declaration of built-in function ‘strlen’ My Lex File looks like: %{ #include <stdio.h> #include <stdlib.h> #include <ctype.h> #include "y.tab.h" void yyerror(const char*); char *ptrStr; %} %START nameState %% "Name:" { BEGIN nameState; } <nameState>.+ { ptrStr = (char *)calloc(strlen(yytext)+1, sizeof(char)); strcpy(ptrStr, yytext); yylval.sValue = ptrStr; return sText; } %% int main(int argc, char *argv[]) { if ( argc < 3 ) { printf("Two args are needed: input and output"); } else { yyin = fopen(argv[1], "r"); yyout = fopen(argv[2], "w"); yyparse(); fclose(yyin); fclose(yyout); } return 0; } My Yacc file is as follows: %{ #include <stdio.h> #include <stdlib.h> #include <ctype.h> #include "y.tab.h" void yyerror(const char*); int yywrap(); extern FILE *yyout; %} %union { int iValue; char* sValue; }; %token <sValue> sText %token nameToken %% StartName: /* for empty */ | sName ; sName: sText { fprintf(yyout, "The Name is: %s", $1); fprintf(yyout, "The Length of the Name is: %d", strlen($1)); } ; %% void yyerror(const char *str) { fprintf(stderr,"error: %s\n",str); } int yywrap() { return 1; } *I was wondering how to remove this warning message. Please any suggestions are highly appreciated! Thanks in advance.

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  • fatal error LNK1104: cannot open file 'libboost_system-vc90-mt-gd-1_43.lib'

    - by Poni
    Made a new project, added main.cpp and wrote the code at this URL: http://www.boost.org/doc/libs/1_43_0/doc/html/boost_asio/example/echo/async_tcp_echo_server.cpp Also, added the appropriate include path. What's next?!?!! It seems like a darn mystery to build a boost code! Been digging on it for more than 10 hours. Can anyone give a straightforward answer on how to build the boost library from the code under windows, VC9? God bless you all.

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  • Class member functions instantiated by traits [policies, actually]

    - by Jive Dadson
    I am reluctant to say I can't figure this out, but I can't figure this out. I've googled and searched Stack Overflow, and come up empty. The abstract, and possibly overly vague form of the question is, how can I use the traits-pattern to instantiate member functions? [Update: I used the wrong term here. It should be "policies" rather than "traits." Traits describe existing classes. Policies prescribe synthetic classes.] The question came up while modernizing a set of multivariate function optimizers that I wrote more than 10 years ago. The optimizers all operate by selecting a straight-line path through the parameter space away from the current best point (the "update"), then finding a better point on that line (the "line search"), then testing for the "done" condition, and if not done, iterating. There are different methods for doing the update, the line-search, and conceivably for the done test, and other things. Mix and match. Different update formulae require different state-variable data. For example, the LMQN update requires a vector, and the BFGS update requires a matrix. If evaluating gradients is cheap, the line-search should do so. If not, it should use function evaluations only. Some methods require more accurate line-searches than others. Those are just some examples. The original version instantiates several of the combinations by means of virtual functions. Some traits are selected by setting mode bits that are tested at runtime. Yuck. It would be trivial to define the traits with #define's and the member functions with #ifdef's and macros. But that's so twenty years ago. It bugs me that I cannot figure out a whiz-bang modern way. If there were only one trait that varied, I could use the curiously recurring template pattern. But I see no way to extend that to arbitrary combinations of traits. I tried doing it using boost::enable_if, etc.. The specialized state information was easy. I managed to get the functions done, but only by resorting to non-friend external functions that have the this-pointer as a parameter. I never even figured out how to make the functions friends, much less member functions. The compiler (VC++ 2008) always complained that things didn't match. I would yell, "SFINAE, you moron!" but the moron is probably me. Perhaps tag-dispatch is the key. I haven't gotten very deeply into that. Surely it's possible, right? If so, what is best practice? UPDATE: Here's another try at explaining it. I want the user to be able to fill out an order (manifest) for a custom optimizer, something like ordering off of a Chinese menu - one from column A, one from column B, etc.. Waiter, from column A (updaters), I'll have the BFGS update with Cholesky-decompositon sauce. From column B (line-searchers), I'll have the cubic interpolation line-search with an eta of 0.4 and a rho of 1e-4, please. Etc... UPDATE: Okay, okay. Here's the playing-around that I've done. I offer it reluctantly, because I suspect it's a completely wrong-headed approach. It runs okay under vc++ 2008. #include <boost/utility.hpp> #include <boost/type_traits/integral_constant.hpp> namespace dj { struct CBFGS { void bar() {printf("CBFGS::bar %d\n", data);} CBFGS(): data(1234){} int data; }; template<class T> struct is_CBFGS: boost::false_type{}; template<> struct is_CBFGS<CBFGS>: boost::true_type{}; struct LMQN {LMQN(): data(54.321){} void bar() {printf("LMQN::bar %lf\n", data);} double data; }; template<class T> struct is_LMQN: boost::false_type{}; template<> struct is_LMQN<LMQN> : boost::true_type{}; // "Order form" struct default_optimizer_traits { typedef CBFGS update_type; // Selection from column A - updaters }; template<class traits> class Optimizer; template<class traits> void foo(typename boost::enable_if<is_LMQN<typename traits::update_type>, Optimizer<traits> >::type& self) { printf(" LMQN %lf\n", self.data); } template<class traits> void foo(typename boost::enable_if<is_CBFGS<typename traits::update_type>, Optimizer<traits> >::type& self) { printf("CBFGS %d\n", self.data); } template<class traits = default_optimizer_traits> class Optimizer{ friend typename traits::update_type; //friend void dj::foo<traits>(typename Optimizer<traits> & self); // How? public: //void foo(void); // How??? void foo() { dj::foo<traits>(*this); } void bar() { data.bar(); } //protected: // How? typedef typename traits::update_type update_type; update_type data; }; } // namespace dj int main() { dj::Optimizer<> opt; opt.foo(); opt.bar(); std::getchar(); return 0; }

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  • Libtool versioning of a library that depends on other libraries.

    - by Artyom
    Hello, I have a framework that uses Boost and CgiCC in the core application and in its interface. How should I version the library binary interface (a.k.a. libtool -version-info)? I have no problems tracking the changes in library itself when I make various changes. As it is clear for me how should I version. But... Both Boost and CgiCC libraries do not provide any backward compatible API/ABI and my library may be linked with quite arbitrary versions Boost and CgiCC so I can't provide any promise about the interfaces, so I can't really specify -version-info because even the same library compiled against different versions of Boost and CgiCC would not be compatible. So... What should I do? How should I version library? I know that I should not depend on Boost and CgiCC interfaces in first place, but this is what I get so far for existing stable version. This issue is addressed in next major release but I still have and want to maintain current release as it is very valuable.

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  • Recommendations for a C++ polymorphic, seekable, binary I/O interface

    - by Trevor Robinson
    I've been using std::istream and ostream as a polymorphic interface for random-access binary I/O in C++, but it seems suboptimal in numerous ways: 64-bit seeks are non-portable and error-prone due to streampos/streamoff limitations; currently using boost/iostreams/positioning.hpp as a workaround, but it requires vigilance Missing operations such as truncating or extending a file (ala POSIX ftruncate) Inconsistency between concrete implementations; e.g. stringstream has independent get/put positions whereas filestream does not Inconsistency between platform implementations; e.g. behavior of seeking pass the end of a file or usage of failbit/badbit on errors Don't need all the formatting facilities of stream or possibly even the buffering of streambuf streambuf error reporting (i.e. exceptions vs. returning an error indicator) is supposedly implementation-dependent in practice I like the simplified interface provided by the Boost.Iostreams Device concept, but it's provided as function templates rather than a polymorphic class. (There is a device class, but it's not polymorphic and is just an implementation helper class not necessarily used by the supplied device implementations.) I'm primarily using large disk files, but I really want polymorphism so I can easily substitute alternate implementations (e.g. use stringstream instead of fstream for unit tests) without all the complexity and compile-time coupling of deep template instantiation. Does anyone have any recommendations of a standard approach to this? It seems like a common situation, so I don't want to invent my own interfaces unnecessarily. As an example, something like java.nio.FileChannel seems ideal. My best solution so far is to put a thin polymorphic layer on top of Boost.Iostreams devices. For example: class my_istream { public: virtual std::streampos seek(stream_offset off, std::ios_base::seekdir way) = 0; virtual std::streamsize read(char* s, std::streamsize n) = 0; virtual void close() = 0; }; template <class T> class boost_istream : public my_istream { public: boost_istream(const T& device) : m_device(device) { } virtual std::streampos seek(stream_offset off, std::ios_base::seekdir way) { return boost::iostreams::seek(m_device, off, way); } virtual std::streamsize read(char* s, std::streamsize n) { return boost::iostreams::read(m_device, s, n); } virtual void close() { boost::iostreams::close(m_device); } private: T m_device; };

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  • Using static mutex in a class

    - by Dmitry Yudakov
    I have a class that I can have many instances of. Inside it creates and initializes some members from a 3rd party library (that use some global variables) and is not thread-safe. I thought about using static boost::mutex, that would be locked in my class constructor and destructor. Thus creating and destroying instances among my threads would be safe for the 3rd party members. class MyClass { static boost::mutex mx; // 3rd party library members public: MyClass(); ~MyClass(); }; MyClass::MyClass() { boost::mutex::scoped_lock scoped_lock(mx); // create and init 3rd party library stuff } MyClass::~MyClass() { boost::mutex::scoped_lock scoped_lock(mx); // destroy 3rd party library stuff } I cannot link because I receive error: undefined reference to `MyClass::mx` Do I need some special initialization of such static member? Is the whole conception of static mutex wrong?

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  • Casting a container of shared_ptr

    - by Jamie Cook
    Hi all, I have a method void foo(list<shared_ptr<Base>>& myList); Which I'm trying to call with a two different types of lists, one of DerivedClass1 and one of DerivedClass2 list<shared_ptr<DerivedClass1>> myList1; foo(myList1); list<shared_ptr<DerivedClass2>> myList2; foo(myList2); However this obviously generates a compiler error error: a reference of type "std::list<boost::shared_ptr<Base>, std::allocator<boost::shared_ptr<Base>>> &" (not const-qualified) cannot be initialized with a value of type "std::list<boost::shared_ptr<DerivedClass1>, std::allocator<boost::shared_ptr<DerivedClass1>>>" Is there any easy way to cast a container of shared_ptr? Of alternate containers that can accomplish this?

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  • C++: conjunction of binds?

    - by Helltone
    Suppose the following two functions: #include <iostream> #include <cstdlib> // atoi #include <cstring> // strcmp #include <boost/bind.hpp> bool match1(const char* a, const char* b) { return (strcmp(a, b) == 0); } bool match2(int a, const char* b) { return (atoi(b) == a); } Each of these functions takes two arguments, but can be transformed into a callable object that takes only one argument by using (std/boost)bind. Something along the lines of: boost::bind(match1, "a test"); boost::bind(match2, 42); I want to be able to obtain, from two functions like these that take one argument and return bool, a callable object that takes two arguments and returns the && of the bools. The type of the arguments is arbitrary. Something like an operator&& for functions that return bool.

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  • Which libraries use the "We Know Where You Live" optimization for std::make_shared?

    - by KnowItAllWannabe
    Over two years ago, Stephan T. Lavavej described a space-saving optimization he implemented in Microsoft's implementation of std::make_shared, and I know from speaking with him that Microsoft has nothing against other library implementations adopting this optimization. If you know for sure whether other libraries (e.g., for Gnu C++, Clang, Intel C++, plus Boost (for boost::make_shared)) have adopted this implementation, please contribute an answer. I don't have ready access to that many make_shared implementations, nor am I wild about digging into the bowels of the ones I have to see if they've implemented the WKWYL optimization, but I'm hoping that SO readers know the answers for some libraries off-hand. I know from looking at the code that as of Boost 1.52, the WKWYL optimization had not been implemented, but Boost is now up to version 1.55. Note that this optimization is different from std::make_shared's ability to avoid a dedicated heap allocation for the reference count used by std::shared_ptr. For a discussion of the difference between WKWYL and that optimication, consult this question.

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  • Calculate rolling / moving average in c or c++

    - by Biohazard
    I know this is achievable with boost as per: Using boost::accumulators, how can I reset a rolling window size, does it keep extra history? But I really would like to avoid using boost. I have googled and not found any suitable or readable examples. Basically I want to track the moving average of an ongoing stream of a stream of floating point numbers using the most recent 1000 numbers as a data sample. What is the easiest way to achieve this?

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  • What's the bug in the following code ?

    - by Johannes
    #include <iostream> #include <algorithm> #include <vector> #include <boost/array.hpp> #include <boost/bind.hpp> int main() { boost::array<int, 4> a = {45, 11, 67, 23}; std::vector<int> v(a.begin(), a.end()); std::vector<int> v2; std::transform(v.begin(), v.end(), v2.begin(), boost::bind(std::multiplies<int>(), _1, 2)); std::copy(v2.begin(), v2.end(), std::ostream_iterator<int>(std::cout, " ")); } When run, this gives a creepy segmentation fault. Please tell me where I'm going wrong.

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  • How do I iterate over a tuple

    - by Caligo
    How can I iterate over a tuple starting from, say, index 1 to 2? The following doesn't work. using boost::fusion::cons; typedef cons<A, cons<B, cons<C, cons<D> > > > MyTuple; MyTuple tuple_; template <class T> struct DoSomething{ DoSomething(T& t) : t_(&t){ } template <class U> void operator()(U u){ boost::fusion::at<mpl::int_<u> >(*t_); } T* t_; }; boost::mpl::for_each< boost::mpl::range_c<int, 1, 3> >( DoSomething<MyTuple>(tuple_) );

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  • why my C++ output executable is so big?

    - by Vincenzo
    I have a rather simple C++ project, which uses boost::regex library. The output I'm getting is 3.5Mb in size. As I understand I'm statically linking all boost .CPP files, including all functions/methods. Maybe it's possible somehow to instruct my linker to use only necessary elements from boost, not all of them? Thanks.

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  • Memory fragmentation @ boost::asio ?

    - by Poni
    I'm pretty much stuck with a question I never got an answer for, a question which addresses an extremely important issue; memory fragmentation at boost::asio. Found nothing at the documentation nor here at SO. The functions at boost::asio, for example async_write() & async_read_some() always allocate something. (in my case it's 144 & 96 bytes respectively, in VC9 Debug build). How do I know about it? I connect a client to the "echo server" example provided with this library. I put a breakpoint at "new.cpp" at the code of "operator new(size_t size)". Then I send "123". Breakpoint is hit! Now using the stack trace I can clearly see that the root to the "new" call is coming from the async_write() & async_read_some() calls I make in the function handlers. So memory fragmentation will come sooner or later, thus I can't use ASIO, and I wish I could! Any idea? Any helpful code example?

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  • Mobile Intel® GMA 4500MHD boost

    - by Andy Smith
    My machine has a Mobile Intel® GMA 4500MHD integrated graphics chipset. The machine is currently running 64 bit windows 7 premium with 3GB of ram (1x1gb and 1x2gb). I note that the Mobile Intel® GMA 4500MHD shares the physical memory to process the graphics. now, the total available graphics memory can be up to 1,340 MB with a 32-bit operating system and 3 GB system memory or 1,759 MB with a 64-bit operating system and 4 GB system memory. I am considering investing in a 4GB stick to replace the 1gb stick bringing the total up to 6gb, mainly for an increase in graphics processing ability. Can anyone let me know what sort of power (if any over the 4gb) I could expect by upgrading to 6GB?

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  • Boost Audio Input on OS X?

    - by alanstorm
    I'm using my 13" Mac Book Pro's audio input functionality with an external microphone (recent vintage, bought around Thanksgiving). I've increased my input volume to the maximum in system preference, but the resulting recorded volume (using iShowU HD) is very low. Is there anyway to increase the input volume/sensitivity beyond Apple's default settings? I've found plenty on google about increasing the OUTPUT volume, but I want to increase the input volume.

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  • Boost Up My Old Laptop Using a SSD

    - by Sina Bizbone
    I have an old laptop Lenovo SL400 (Core2Due T9550 2.66GHz / 4GB DDR2 Ram). Since I can't afford to buy a new laptop, I thought maybe I could throw an ADATA SP600 64GB SSD as primary drive and move my current HDD to DVD-ROM space by using HDDCADDY. I know that 64gb will come short after installing Visual Studio, SQL Server, etc. So is there anyway to just install the kernel part of windows on SSD and the rest on HDD. Doesn't windows have built-in support to do this? (ReadyBoost is out of picture since it's just simple caching)

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  • error in coding a lexer in c

    - by mekasperasky
    #include<stdio.h> #include<ctype.h> #include<string.h> /* this is a lexer which recognizes constants , variables ,symbols, identifiers , functions , comments and also header files . It stores the lexemes in 3 different files . One file contains all the headers and the comments . Another file will contain all the variables , another will contain all the symbols. */ int main() { int i=0,j,k,count=0; char a,b[100],c[10000],d[100]; memset ( d, 0, 100 ); j=30; FILE *fp1,*fp2; fp1=fopen("source.txt","r"); //the source file is opened in read only mode which will passed through the lexer fp2=fopen("lext.txt","w"); //now lets remove all the white spaces and store the rest of the words in a file if(fp1==NULL) { perror("failed to open source.txt"); //return EXIT_FAILURE; } i=0; k=0; while(!feof(fp1)) { a=fgetc(fp1); if(a!=' '&&a!='\n') { if (!isalpha(a)) { switch(a) { case '+':{fprintf(fp2,"+ ----> PLUS \n"); i=0;break;} case '-':{fprintf(fp2,"- ---> MINUS \n"); i=0;break;} case '*':{fprintf(fp2, "* --->MULT \n"); i=0;break;} case '/':{fprintf(fp2, "/ --->DIV \n"); i=0;break;} //case '+=':fprintf(fp2, "%.20s\n", "ADD_ASSIGN"); //case '-=':fprintf(fp2, "%.20s\n", "SUB_ASSIGN"); case '=':{fprintf(fp2, "= ---> ASSIGN \n"); i=0;break;} case '%':{fprintf(fp2, "% ---> MOD \n"); i=0;break;} case '<':{fprintf(fp2, "< ---> LESSER_THAN \n"); i=0;break;} case '>':{fprintf(fp2, "> --> GREATER_THAN \n"); i=0;break;} //case '++':fprintf(fp2, "%.20s\n", "INCREMENT"); //case '--':fprintf(fp2, "%.20s\n", "DECREMENT"); //case '==':fprintf(fp2, "%.20s\n", "ASSIGNMENT"); case ';':{fprintf(fp2, "; --->SEMI_COLUMN \n"); i=0;break;} case ':':{fprintf(fp2, ": --->COLUMN \n"); i=0;break;} case '(':{fprintf(fp2, "( --->LPAR \n"); i=0;break;} case ')':{fprintf(fp2, ") --->RPAR \n"); i=0;break;} case '{':{fprintf(fp2, "{ --->LBRACE \n"); i=0;break;} case '}':{fprintf(fp2, "} ---> RBRACE \n"); i=0;break;} } } else { d[i]=a; //printf("%c\n",d[i]); i=i+1; } //} /* we can make the lexer more complex by including even more depths of checks for the symbols*/ } else { d[i+1]='\0'; printf("\n"); if((strcmp(d,"if ")==0)){fprintf(fp2,"if ----> IDENTIFIER \n"); //printf("%s \n",d); memset ( d, 0, 100 ); //printf("%s \n",d); count=count+1;} else if(strcmp(d,"then")==0){fprintf(fp2,"then ----> IDENTIFIER \n"); count=count+1;} else if(strcmp(d,"else")==0){fprintf(fp2,"else ----> IDENTIFIER \n"); count=count+1;} else if(strcmp(d,"switch")==0){fprintf(fp2,"switch ----> IDENTIFIER \n"); count=count+1;} else if(strcmp(d,"printf")==0){fprintf(fp2,"prtintf ----> IDENTIFIER \n"); count=count+1;} else if(strcmp(d,"scanf")==0){fprintf(fp2,"scanf ----> IDENTIFIER \n"); count=count+1;} else if(strcmp(d,"NULL")==0){fprintf(fp2,"NULL ----> IDENTIFIER \n"); count=count+1;} else if(strcmp(d,"int")==0){fprintf(fp2,"INT ----> IDENTIFIER \n"); count=count+1;} else if(strcmp(d,"char")==0){fprintf(fp2,"char ----> IDENTIFIER \n"); count=count+1;} else if(strcmp(d,"float")==0){fprintf(fp2,"float ----> IDENTIFIER \n"); count=count+1;} else if(strcmp(d,"long")==0){fprintf(fp2,"long ----> IDENTIFIER \n"); count=count+1;} else if(strcmp(d,"double")==0){fprintf(fp2,"double ----> IDENTIFIER \n"); count=count+1;} else if(strcmp(d,"const")==0){fprintf(fp2,"const ----> IDENTIFIER \n"); count=count+1;} else if(strcmp(d,"continue")==0)fprintf(fp2,"continue ----> IDENTIFIER \n"); else if(strcmp(d,"size of")==0){fprintf(fp2,"size of ----> IDENTIFIER \n"); count=count+1;} else if(strcmp(d,"register")==0){fprintf(fp2,"register ----> IDENTIFIER \n"); count=count+1;} else if(strcmp(d,"short")==0){fprintf(fp2,"short ----> IDENTIFIER \n"); count=count+1;} else if(strcmp(d,"auto")==0){fprintf(fp2,"auto ----> IDENTIFIER \n"); count=count+1;} else if(strcmp(d,"while")==0){fprintf(fp2,"while ----> IDENTIFIER \n"); count=count+1;} else if(strcmp(d,"do")==0){fprintf(fp2,"do ----> IDENTIFIER \n"); count=count+1;} else if(strcmp(d,"case")==0){fprintf(fp2,"case ----> IDENTIFIER \n"); count=count+1;} else if (isdigit(d[i])) { fprintf(fp2,"%s ---->NUMBER",d); } else if (isalpha(a)) { fprintf(fp2,"%s ----> Variable",d); //printf("%s",d); // memset ( d, 0, 100 );} //fprintf(fp2, "s\n", b); i=0; k=k+1; continue; } i=i+1; k=k+1; } fclose(fp1); fclose(fp2); printf("%d",count); return 0; } In this code , my source.txt has if (a+b) stored . But only ( , + and ) is getting written into lext.txt and not the identifier if or the variable a and b . Any particular reason why?

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  • expected identifier or '(' before '{' token in Flex

    - by user1829177
    I am trying to use Flex to parse 'C' source code. Unfortunately I am getting the error "expected identifier or '(' before '{' token" on lines 1,12,13,14... . Any ideas why? %{ %} digit [0-9] letter [a-zA-Z] number (digit)+ id (letter|_)(letter|digit|_)* integer (int) character (char) comma [,] %% {integer} {return INT;} {character} {return CHAR;} {number} {return NUM;} {id} {return IDENTIFIER;} {comma} {return ',';} [-+*/] {return *yytext;} . {} %% main() { yylex(); } The corresponding flex file is as shown below: %{ #include <ctype.h> #include <stdio.h> #include "myhead.h" #include "mini.l" #define YYSTYPE double # undef fprintf %} %token INT %token CHAR %token IDENTIFIER %token NUM %token ',' %left '+' '-' %left '*' '/' %right UMINUS %% lines:lines expr '\n' {printf("%g\n",$2);} |lines '\n' |D | ; expr :expr '*' expr {$$=$1*$3;} |expr '/' expr {$$=$1/$3;} |expr '+' expr {$$=$1+$3;} |expr '-' expr {$$=$1+$3;} |'(' expr ')' {$$=$2;} |'-' expr %prec UMINUS {$$=-$2;} |IDENTIFIER {} |NUM {} ; T :INT {} |CHAR {} ; L :L ',' IDENTIFIER {} |IDENTIFIER {} ; D :T L {printf("T is %g, L is %g",$1,$2);} ; %% /*void yyerror (char *s) { fprintf (stderr, "%s\n", s); } */ I am compiling the generated code using the command: gcc my_file.c -ly

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