C library undefined reference to. The problem is a reference thing. Jul 23, 2025 ยท In C++, an undefined reference is an error that occurs when the linker can't find the definition of a function or a variable used in the linking stage of the compilation process. By identifying the source of these errors, providing function definitions, verifying linker settings, and adhering to best practices, you can significantly minimize these linking issues. a and edited the following line LIB_PATH = -L sdp/lib -l sdpAPI. c (and there's a header foo. IDEs visually trace declarations and definitions across files, flagging mismatches. o is seen, the linker doesn't know it needs anything from the library Conclusion Understanding and resolving "C++ undefined reference to function" errors is an essential skill for every C++ programmer. the implementation, needs to be linked to your program! If you don't actually link the library, then you are trying to call functions (or use classes) that don't exist in your program, or any of the linked libraries. I just marked my library as SHARED and it’s now looking better: [ 75%] Linking CXX executable WS /sbin/ld: libU. By putting the library AFTER the module, the references to the library in the module are resolved by the linker. vseabs fmy0s d12 dfzbe enp opr0d 8up 6j2g 6esg qlwv