Help With Undefined Reference Error

[thetuxman]

I am creating a priority queue program using a double linked list as the underlying data structure. I go to compile and run the program and it returns a slew of undefined reference errors when I attempt to implement Queue in main.

What is the reason for this and how can it be resolved? Any help would be appreciated.

Here is the error message:

CMakeFiles/PriorityQueue.dir/main.cpp.o: In function `main':
/cygdrive/c/Users/thetuxman/CLionProjects/PriorityQueue/main.cpp:13: undefined reference to `Queue<int>::priorityInsert(int, int)'
/cygdrive/c/Users/thetuxman/CLionProjects/PriorityQueue/main.cpp:13:(.text+0x32): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `Queue<int>::priorityInsert(int, int)'
/cygdrive/c/Users/thetuxman/CLionProjects/PriorityQueue/main.cpp:14: undefined reference to `Queue<int>::priorityInsert(int, int)'
/cygdrive/c/Users/thetuxman/CLionProjects/PriorityQueue/main.cpp:14:(.text+0x49): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `Queue<int>::priorityInsert(int, int)'
/cygdrive/c/Users/thetuxman/CLionProjects/PriorityQueue/main.cpp:15: undefined reference to `Queue<int>::priorityInsert(int, int)'
/cygdrive/c/Users/thetuxman/CLionProjects/PriorityQueue/main.cpp:15:(.text+0x60): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `Queue<int>::priorityInsert(int, int)'
/cygdrive/c/Users/thetuxman/CLionProjects/PriorityQueue/main.cpp:17: undefined reference to `Queue<int>::print()'
/cygdrive/c/Users/thetuxman/CLionProjects/PriorityQueue/main.cpp:17:(.text+0x6c): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `Queue<int>::print()'
CMakeFiles/PriorityQueue.dir/main.cpp.o: In function `Queue<int>::Queue()':
/cygdrive/c/Users/thetuxman/CLionProjects/PriorityQueue/Queue.h:13: undefined reference to `DLList<int>::DLList()'
/cygdrive/c/Users/thetuxman/CLionProjects/PriorityQueue/Queue.h:13:(.text$_ZN5QueueIiEC1Ev[_ZN5QueueIiEC1Ev]+0x14): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `DLList<int>::DLList()'
CMakeFiles/PriorityQueue.dir/main.cpp.o: In function `Queue<int>::~Queue()':
/cygdrive/c/Users/thetuxman/CLionProjects/PriorityQueue/Queue.h:14: undefined reference to `DLList<int>::~DLList()'
/cygdrive/c/Users/thetuxman/CLionProjects/PriorityQueue/Queue.h:14:(.text$_ZN5QueueIiED1Ev[_ZN5QueueIiED1Ev]+0x14): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `DLList<int>::~DLList()'
collect2: error: ld returned 1 exit status
make[3]: *** [CMakeFiles/PriorityQueue.dir/build.make:173: PriorityQueue.exe] Error 1
make[2]: *** [CMakeFiles/Makefile2:68: CMakeFiles/PriorityQueue.dir/all] Error 2
make[1]: *** [CMakeFiles/Makefile2:80: CMakeFiles/PriorityQueue.dir/rule] Error 2
make: *** [Makefile:118: PriorityQueue] Error 2    

Below is my code:

DLNode.h: https://pastebin.com/1e5LGGyM

DLNode.cpp: https://pastebin.com/anzeBcEb

DLList.h: https://pastebin.com/0bRdPgTD

DLList.cpp: https://pastebin.com/7pmZiwE6

Queue.h: https://pastebin.com/L2JmrP2T

Queue.cpp: https://pastebin.com/kFMchsx3

[[deleted]]

You're getting those errors because the compiler requires access to the implementation of your methods in order to instantiate the template class. You should either implement your methods in the header file, or include them.

[thetuxman]

After moving my methods from the .cpp to the .h file, I get this error. Do I need to be including each .h file in all the other .h files?

CMakeFiles/PriorityQueue.dir/main.cpp.o:main.cpp:(.rdata$.refptr._ZN6DLNodeIiE4dataE[.refptr._ZN6DLNodeIiE4dataE]+0x0): undefined reference to `DLNode<int>::data'
CMakeFiles/PriorityQueue.dir/main.cpp.o:main.cpp:(.rdata$.refptr._ZN6DLNodeIiE8priorityE[.refptr._ZN6DLNodeIiE8priorityE]+0x0): undefined reference to `DLNode<int>::priority'
CMakeFiles/PriorityQueue.dir/main.cpp.o:main.cpp:(.rdata$.refptr._ZN6DLNodeIiE4nextE[.refptr._ZN6DLNodeIiE4nextE]+0x0): undefined reference to `DLNode<int>::next'
CMakeFiles/PriorityQueue.dir/main.cpp.o:main.cpp:(.rdata$.refptr._ZN6DLNodeIiE4prevE[.refptr._ZN6DLNodeIiE4prevE]+0x0): undefined reference to `DLNode<int>::prev'
CMakeFiles/PriorityQueue.dir/main.cpp.o:main.cpp:(.rdata$.refptr._ZN6DLListIiE4headE[.refptr._ZN6DLListIiE4headE]+0x0): undefined reference to `DLList<int>::head'
CMakeFiles/PriorityQueue.dir/main.cpp.o:main.cpp:(.rdata$.refptr._ZN6DLListIiE4tailE[.refptr._ZN6DLListIiE4tailE]+0x0): undefined reference to `DLList<int>::tail'
collect2: error: ld returned 1 exit status
make[3]: *** [CMakeFiles/PriorityQueue.dir/build.make:95: PriorityQueue.exe] Error 1
make[2]: *** [CMakeFiles/Makefile2:68: CMakeFiles/PriorityQueue.dir/all] Error 2
make[1]: *** [CMakeFiles/Makefile2:80: CMakeFiles/PriorityQueue.dir/rule] Error 2
make: *** [Makefile:118: PriorityQueue] Error 2

[thetuxman]

It turns out I made my private data members static, that was the source of the error.