Can't build very simple tcl application - tcl

Question

I'm trying to write a very simple Tcl application in C++:
#include <tcl.h>
#include <iostream>
int main (int argc, char *argv[])
{
std::cout << "Calling Tcl_FindExecutable." << std::endl;
Tcl_FindExecutable (argv[0]);
std::cout << "Calling Tcl_CreateInterp." << std::endl;
Tcl_Interp *pInterp = Tcl_CreateInterp ();
if (Tcl_Eval (pInterp, "puts stdout {Hello, World!}") != TCL_OK)
{
std::cerr << "Error: " << Tcl_GetStringResult (pInterp) << std::endl;
return (0);
}
if (Tcl_Eval (pInterp, "puts stdout [info nameofexecutable]") != TCL_OK)
{
std::cerr << "Error: " << Tcl_GetStringResult (pInterp) << std::endl;
return (0);
}
return (1);
}
I can compile it via g++ -c Wall -I/opt/ActiveTcl-8.6/include noddy.cpp -o noddy.o
but when I link it, with g++ -L/opt/ActiveTcl-8.6/lib -ltcl8.6 -o noddy noddy.o
I get errors saying that all the Tcl library procedures are undefined.
What am I doing wrong, please?
Edit
The actual commands were
$ g++ -c -Wall -I/opt/ActiveTcl-8.6/include noddy.cpp -o noddy.o
$ g++ -L/opt/ActiveTcl-8.6/lib -ltcl8.6 -o noddy noddy.o
noddy.o: In function 'main':
noddy.cpp:(.text+0x37): undefined reference to 'Tcl_FindExecutable'
noddy.cpp:(.text+0x60): undefined reference to 'Tcl_CreateInterp'
noddy.cpp:(.text+0x78): undefined reference to 'Tcl_Eval'
noddy.cpp:(.text+0x8d): undefined reference to 'Tcl_GetStringResult'
noddy.cpp:(.text+0xda): undefined reference to 'Tcl_Eval'
noddy.cpp:(.text+0xef): undefined reference to 'Tcl_GetStringResult'
collect2: ld returned 1 exit status

Answer 1

In link statements the order of object modules and libraries is significant. You should include the object first and then the libraries (redone as C to avoid installing g++):
> gcc -Wall -I/opt/tcl/include -c noddy.c
> gcc -o noddy.exe noddy.o -L/opt/tcl/lib -ltcl86
> noddy
Calling Tcl_FindExecutable.
Calling Tcl_CreateInterp.
Hello, World!
C:/Code/noddy.exe
But:
> gcc -o noddy.exe -L/opt/tcl/lib -ltcl86 noddy.o
noddy.o:noddy.c:(.text+0x23): undefined reference to '_imp__Tcl_FindExecutable'
noddy.o:noddy.c:(.text+0x36): undefined reference to '_imp__Tcl_CreateInterp'
noddy.o:noddy.c:(.text+0x50): undefined reference to '_imp__Tcl_Eval'
noddy.o:noddy.c:(.text+0x62): undefined reference to '_imp__Tcl_GetStringResult'
noddy.o:noddy.c:(.text+0x9b): undefined reference to '_imp__Tcl_Eval'
noddy.o:noddy.c:(.text+0xad): undefined reference to '_imp__Tcl_GetStringResult'
e:/opt/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: noddy.o: bad reloc address 0x20 in section '.eh_frame'
e:/opt/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: final link failed: Invalid operation
collect2.exe: error: ld returned 1 exit status