Table of Contents
What is an undefined reference error?
An “Undefined Reference” error occurs when we have a reference to object name (class, function, variable, etc.) Thus when the linker cannot find the definition of a linked object, it issues an “undefined reference” error. As clear from definition, this error occurs in the later stages of the linking process.
Why do I get undefined reference error when linking?
We see here a declaration of foo ( int foo ();) but no definition of it (actual function). So we provided the compiler with the function header, but there was no such function defined anywhere, so the compilation stage passes but the linker exits with an Undefined reference error. Now this code will compile.
How to fix undefined reference in foo.c?
Then the fix is to link both the object file from foo.c and undefined_reference.c, or to compile both the source files: A more complex case is where libraries are involved, like in the code:
What to do if there are undefined references in latex?
Getting a warning about undefined references after the first latex run is nothing to worry about; just rerun latex once or twice more, and all cross-references should be resolved (including the one to lastpage).
When to run compilation stage with undefined reference?
(Note that there are platforms such as macOS where -lm is not needed, but when you get the undefined reference, the library is needed.) So we run the compilation stage again, this time specifying the library (after the source or object files): And it works!
When do I get an undefined referrence error?
Undefined referrence: An “Undefined Reference” error’s occurs when we have a reference to an object name (class, function, variable, and so on) in our program, and the linker cannot find its definitions when it tries to search for it in all the related item files and
What does ” undefined reference ” mean in C + +?
Put simply, the “undefined reference” error means you have a reference (nothing to do with the C++ reference type) to a name (function, variable, constant etc.) in your program that the linker cannot find a definition for when it looks through all the object files and libraries…
Then the fix is to link both the object file from foo.c and undefined_reference.c, or to compile both the source files: A more complex case is where libraries are involved, like in the code:
Why do I get ” undefined reference ” error in GCC?
The problem is probably occurring because you’re compiling only Main.c when you need to be compiling Main.c and Person.c at the same time. Try compiling it as gcc Main.c Person.c -o MyProgram. Whenever you have multiple files, they all need to be specified when compiling in order to resolve external references, as is the case here.