Gcc Linker Error Messages
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foreword by Richard M. StallmanPaperback (6"x9"), 144 pagesISBN 0954161793RRP £12.95 ($19.95)"A wonderfully thorough guide... well-written, seriously usable information" --- Linux User and linker error c++ Developer Magazine (Issue 40, June 2004) Get a printed copy>>>An Introduction to
Linker Error In C
GCCBuy the book here!>>>support free documentation 13.3 Linker error messages file not recognized: File format not recognized GCC uses linker error undefined symbol the extension of a file, such as ‘.c’ or ‘.cc’, to determine its content. If the extension is missing GCC cannot recognize the file type and will give this error. linking error undefined reference to function Example: #include
Linker Error Undefined Reference To
in this case ‘hello.c’. undefined reference to `foo' collect2: ld returned 1 exit status This error occurs when a program uses a function or variable which is not defined in any of the object files or libraries supplied to the linker. It can be caused by a missing library or the use of an incorrect name. In the error message above, the program ‘collect2’ is part of the linker. Example: int foo(void); int main (void) { foo(); return 0; } If this program is compiled without linking to a library or object file containing the function foo() there will be an undefined reference error. /usr/lib/crt1.o(.text+0x18): undefined reference to `main' This error is a special case of the error above, when the missing function is main. In C and C++, every program must have a main function (where execution starts). When compiling an individual source file without a main function, use the option -c (see section 2.4.1 Creating object files from source files). <<< previous table of contents next >>> ISBN 0954161793An Introduction to GCC - for the GNU compilers gcc and g++See
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 linker error in turbo c Us Dealing with Compiler Errors - Surviving the Compilation Process By Alex linker error c++ unresolved external symbol Allain It's your first C (or C++) program--it's not that long, and you're about to compile it. You hit
Linker Error Xcode
compile (or enter the build command) and wait. Your compiler spits out fifty lines of text. You pick out words like "warning and "error". Does that mean it worked? you wonder. http://www.network-theory.co.uk/docs/gccintro/gccintro_95.html You look for the resulting executable. Nothing. Damn, you think, I guess I have to figure out what this all means... The 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 http://www.cprogramming.com/tutorial/compiler_linker_errors.html 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 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
C++ programmers sometimes spend lots of time trying to understand and repair compiler and linker errors. If you can't understand the message, you're stuck. With a compiler error, the problem is easier to diagnose because it is related to the compilation of one source code module and https://www.ics.com/designpatterns/book/commonlinkererrors.html the header files it includes. The compiler generally tells you the exact location of any http://www.keil.com/support/docs/3136 error that it detects. With a linker error, the problem is related to how your source code modules link together. When the linker stage is reached, all the individual modules have compiled without errors. Linker errors can be caused by bugs in C++ code, but they can also be a result of mistakes in the project file. Error: Unable to linker error find libxxx.so.x For Win32 Users At compile-time, your IDE needs to find the .DLL. To remedy this situation, drill into your menu structure until you find project -> properties -> C/C++ build -> libraries. Here, you can add a 3rd party library, and you'll be asked in a dialog for the location of headers and DLL files. At runtime, your PATH system environment variable must contain the directory where the required DLLs are located. Installing a linker error c++ library means making it available for more than a single user on a system. It is also possible to reuse a library without installing it. All libraries that you reuse must either be installed or placed in a directory listed in your LD_LIBRARY_PATH. When you reuse a library for the first time, you will probably see this error message. It means that the linker can not find the library. When the gnu linker looks for a shared object, it checks at least two places: The directories specified in LD_LIBRARY_PATH Installed libraries referenced from a cache file called /etc/ld.so.cache The Cache File: ld.so.cache The cache file provides fast lookup of shared objects found in the directories specified in /etc/ld.so.conf. Some directories you might find there are /lib /usr/lib /usr/X11R6/lib /usr/i486-linuxlibc1/lib /usr/local/lib /usr/lib/mozilla If you use a Linux package installer to install a library, it probably makes the proper changes to ld.so.conf and rebuilds your cache file. However, if you manually compile and install libraries, it may be necessary for you to edit this file. Afterward, you can rebuild the cache file with the command: ldconfig. Error: undefined reference to identifier This is the most common and, probably, the most annoying linker error of all. It means that the linker cannot find the definition of some named entity in your code. Following is some out
30 Days In the Last 90 Days In the Last 6 Months Technical Support Overview Search Contact Assistance Request Feedback Support Resources Support Knowledgebase Article Index Top 10 Articles Product Manuals Application Notes Downloads Product Updates Discussion Forum Books Product Information Software & Hardware Products ARM Development ToolsC166 Development ToolsC51 Development ToolsC251 Development ToolsDebug AdaptersEvaluation Boards Product Brochures Newsletters Home/Technical Support GCC: LINKER ERROR (UNDEFINED REFERENCE WITH C++) Information in this article applies to: GNU C Compiler for ARM All Versions SYMPTOM The GNU linker gives error messages while linking an application which contains class declarations and class instances. CAUSE The class declaration specifies a constructor and/or destructor, but the constructor/destructor function is missing. class clf { public: clf(); // Constructor (ctor) ~clf(); // Destructor (dtor) int n1, n2, n3; }; clf clf1; // class object int main (void) { return (0); } The linker gives the error messages which look like the following ones: .\obj\blinky.o(.text+0x40): In function '__static_initialization_and_destruction_0': /cygdrive/c/Keil/ARM/GNU/Examples/Blinky/blinky.cpp(92): error: undefined reference to 'clf::~clf [in-charge]() 'blinky.o' (.text+0x44):blinky.cpp:92: undefined reference to 'clf::clf[in-charge]()' RESOLUTION Add the constructor(s) and/or destructor(s) as shown below: class clf { public: clf(); // Constructor (ctor) ~clf(); // Destructor (dtor) int n1, n2, n3; }; clf::clf () { // define ctor n1 = n2 = n3 = 0; } clf::~clf() { // define dtor } clf clf1; // class object int main (void) { return (0); } SEE ALSO µVision DEBUGGER: SOURCE LEVEL DEBUGGING WITH GNU ARM Last Reviewed: Monday, December 10, 2012 Did this article provide the answer you needed? Yes No Not Sure Products Development Tools ARM C166 C51 C251 µVision IDE and Debugger Hardware & Collateral ULINK Debug Adaptors Evaluation Boards Product Brochures Device Database Distributors