C Program Linker Error
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Practice Problems Quizzes Resources Source Code Source Code Snippets C and C++ Tips Finding a Job References Function Reference Syntax Reference Programming FAQ Getting Help Message Board Email About Us Dealing with Compiler Errors - Surviving the Compilation Process linker error in c graphics program By Alex Allain It's your first C (or C++) program--it's not that long, and you're
C Linker Error Undefined Reference
about to compile it. You hit compile (or enter the build command) and wait. Your compiler spits out fifty lines of text. linker error undefined reference to winmain@16' dev c++ You pick out words like "warning and "error". Does that mean it worked? you wonder. You look for the resulting executable. Nothing. Damn, you think, I guess I have to figure out what this all means... The
Linker Error Static Variable C++
Types of Compilation Errors First, let's distinguish between the types of errors: most compilers will give three types of compile-time alerts: compiler warnings, compiler errors, and linker errors. Although you don't want to ignore them, compiler warnings aren't something severe enough to actually keep your program from compiling. Usually, compiler warnings are an indication that something might go wrong at runtime. How can the compiler know this at all? You might be making how to solve linker error in c a typical mistake that the compiler knows about. A common example is using the assignment operator ('=') instead of the equality operator ('==') inside an if statement. Your compiler may also warn you about using variables that haven't been initialized and other similar mistakes. Generally, you can set the warning level of your compiler--I like to keep it at its highest level so that my compiler warnings don't turn in to bugs in the running program ('runtime bugs'). Nevertheless, compiler warnings aren't going to stop you from getting your program working (unless you tell your compiler to treat warnings as errors), so they're probably a bit less frustrating than errors. Errors are conditions that prevent the compiler from completing the compilation of your files. Compiler errors are restricted to single source code files and are the result of 'syntax errors'. What this really means is that you've done something that the compiler cannot understand. For instance, the statement "for(;)" isn't correct syntax because a for loop always needs to have three parts. Although the compiler would have expected a semicolon, it would also have expected a conditional expression, so the error message you get might be something like "line 53, unexpected parenthesis ')'". Note, also, that compiler errors will always include a line number at which the error was
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Linker Error In Turbo C
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How To Remove Linker Error In C
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some background. What is the linker? Consider the framework of a typical C++ program shown below. The main program in main.cpp uses a class called Type1, declared in the file type1.h-no executable code appears here-and defined, with executable code, in the http://inst.eecs.berkeley.edu/~selfpace/studyguide/9F.sg/Output/linker.errors.html file type1.cpp. A private class variable in the Type1 class is an object of Type2, http://stackoverflow.com/questions/17764661/multiple-definition-of-linker-error similarly declared in the file type2.h and defined in the file type2.cpp. main.cpp #include
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Multiple definition of … linker error up vote 16 down vote favorite 4 I defined a special file: config.h My project also has files: t.c, t.h pp.c, pp.h b.c b.h l.cpp and #includes: in t.c: #include "t.h" #include "b.h" #include "pp.h" #include "config.h" in b.c: #include "b.h" #include "pp.h" in pp.c: #include "pp.h" #include "config.h" in l.cpp: #include "pp.h" #include "t.h" #include "config.h" there are no include directives in my *.h files, only in *.c files. I defined this in config.h: const char *names[i] = { "brian", "stefan", "steve" }; and need that array in l.cpp, t.c, pp.c but Im getting this error: pp.o:(.data+0x0): multiple definition of `names' l.o:(.data+0x0): first defined here t.o:(.data+0x0): multiple definition of `names' l.o:(.data+0x0): first defined here collect2: ld returned 1 exit status make: *** [link] Error 1 I have include guards in every *.h file I use in my project. Any help solving this? c linker linker-error share|improve this question edited Jul 20 '13 at 17:25 asked Jul 20 '13 at 17:17 mazix 72451841 possible duplicate of multiple definition linker error after adding a function to a previously linking file –user529758 Jul 20 '13 at 18:36 add a comment| 2 Answers 2 active oldest votes up vote 39 down vote accepted Don't define variables in headers. Put declarations in header and definitions in one of the .c files. In config.h extern const char *names[]; In some .c file: const char *names[] = { "brian", "stefan", "steve" }; If you put a definition of a global variable in a header file, then this definition will go to every .c file that includes this header, and you will get multiple definition error because a varible may be declared multiple times but can be defined only once. share|improve this answer edited Jul 20 '13 at 17:35 answered Jul 20 '13 at 17:23 Yu Hao 84k18115177 solved! :) Could you please tell me why I shouldnt put declarations in h*. files? –mazix Jul 20 '13 at 17:30 3 So it won't do this. Use *.h files just to reference information. You have to remember that "include" means it is including all the *.h i