C++ compilation error from OPS 2.4.2 to a more recent one

[GFiorillo]

Dear All,
I have been compiling OpenSees' static library [version 2.4.2 (rev 5585)] up to Ubuntu 18.04 and used in my C++ code without any issues. I recently moved to Ubuntu 20.04 and I could not compile the 2.4.2 version (i guess because of the 8.5 tcl's version which is not available anymore on 20.04). I downloaded the recent 3.4.0 version. I am able to compile the libraries in Ubuntu 20.04, but when I compile my C++ code I get the error listed below. I tried to move the static libraries to a local location. The result did not change. I also tried to find a solution on the web without luck. I was wondering if you could please help me understand why this happens.
Thank you.

/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(Steel01.o): in function `OPS_Steel01()':
Steel01.cpp:(.text+0x2b27): undefined reference to `ops_getintinput_'
/usr/bin/ld: Steel01.cpp:(.text+0x2b34): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: Steel01.cpp:(.text+0x2b51): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(ElasticSection3d.o): in function `OPS_ElasticSection3d()':
ElasticSection3d.cpp:(.text+0x18e2): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: ElasticSection3d.cpp:(.text+0x1905): undefined reference to `ops_getintinput_'
/usr/bin/ld: ElasticSection3d.cpp:(.text+0x1922): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(SectionAggregator.o): in function `OPS_UniaxialSection()':
SectionAggregator.cpp:(.text+0x406d): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: SectionAggregator.cpp:(.text+0x4091): undefined reference to `ops_getintinput_'
/usr/bin/ld: SectionAggregator.cpp:(.text+0x409e): undefined reference to `ops_getstring'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(SectionAggregator.o): in function `OPS_SectionAggregator()':
SectionAggregator.cpp:(.text+0x4891): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: SectionAggregator.cpp:(.text+0x48b4): undefined reference to `ops_getintinput_'
/usr/bin/ld: SectionAggregator.cpp:(.text+0x4916): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: SectionAggregator.cpp:(.text+0x492a): undefined reference to `ops_getintinput_'
/usr/bin/ld: SectionAggregator.cpp:(.text+0x496a): undefined reference to `ops_getstring'
/usr/bin/ld: SectionAggregator.cpp:(.text+0x4a4e): undefined reference to `OPS_ResetCurrentInputArg'
/usr/bin/ld: SectionAggregator.cpp:(.text+0x4b11): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: SectionAggregator.cpp:(.text+0x4b1b): undefined reference to `ops_getstring'
/usr/bin/ld: SectionAggregator.cpp:(.text+0x4c27): undefined reference to `ops_getintinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(Node.o): in function `OPS_Node()':
Node.cpp:(.text+0x3fa9): undefined reference to `ops_getdomain_()'
/usr/bin/ld: Node.cpp:(.text+0x3fb6): undefined reference to `ops_getndm_'
/usr/bin/ld: Node.cpp:(.text+0x3fbf): undefined reference to `ops_getndf_'
/usr/bin/ld: Node.cpp:(.text+0x3fe5): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: Node.cpp:(.text+0x400e): undefined reference to `ops_getintinput_'
/usr/bin/ld: Node.cpp:(.text+0x403b): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: Node.cpp:(.text+0x40b1): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: Node.cpp:(.text+0x40be): undefined reference to `ops_getstring'
/usr/bin/ld: Node.cpp:(.text+0x41cd): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: Node.cpp:(.text+0x41f2): undefined reference to `ops_getintinput_'
/usr/bin/ld: Node.cpp:(.text+0x4221): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: Node.cpp:(.text+0x4247): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: Node.cpp:(.text+0x42a1): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: Node.cpp:(.text+0x42c7): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: Node.cpp:(.text+0x42f1): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: Node.cpp:(.text+0x4319): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: Node.cpp:(.text+0x43a1): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: Node.cpp:(.text+0x43d4): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(SP_Constraint.o): in function `OPS_HomogeneousBC()':
SP_Constraint.cpp:(.text+0x713): undefined reference to `ops_getdomain_()'
/usr/bin/ld: SP_Constraint.cpp:(.text+0x724): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: SP_Constraint.cpp:(.text+0x731): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: SP_Constraint.cpp:(.text+0x758): undefined reference to `ops_getintinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(SP_Constraint.o): in function `OPS_HomogeneousBC_X()':
SP_Constraint.cpp:(.text+0x9ff): undefined reference to `ops_getdomain_()'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xa10): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xa32): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xa67): undefined reference to `ops_getintinput_'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xa86): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xa9b): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xb0e): undefined reference to `OPS_ResetCurrentInputArg'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xb21): undefined reference to `ops_getstring'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xb4c): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(SP_Constraint.o): in function `OPS_HomogeneousBC_Y()':
SP_Constraint.cpp:(.text+0xc1f): undefined reference to `ops_getdomain_()'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xc30): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xc52): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xc87): undefined reference to `ops_getintinput_'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xca6): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xcbb): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xd36): undefined reference to `OPS_ResetCurrentInputArg'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xd41): undefined reference to `ops_getstring'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xd6c): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(SP_Constraint.o): in function `OPS_HomogeneousBC_Z()':
SP_Constraint.cpp:(.text+0xe3f): undefined reference to `ops_getdomain_()'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xe50): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xe72): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xea7): undefined reference to `ops_getintinput_'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xec6): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xedb): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xf56): undefined reference to `OPS_ResetCurrentInputArg'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xf61): undefined reference to `ops_getstring'
/usr/bin/ld: SP_Constraint.cpp:(.text+0xf8c): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(LoadPattern.o): in function `OPS_LoadPattern()':
LoadPattern.cpp:(.text+0x2f51): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: LoadPattern.cpp:(.text+0x2f74): undefined reference to `ops_getintinput_'
/usr/bin/ld: LoadPattern.cpp:(.text+0x2f8d): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: LoadPattern.cpp:(.text+0x2f9b): undefined reference to `ops_getstring'
/usr/bin/ld: LoadPattern.cpp:(.text+0x3029): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(LinearSeries.o): in function `OPS_LinearSeries()':
LinearSeries.cpp:(.text+0x57c): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: LinearSeries.cpp:(.text+0x629): undefined reference to `ops_getstring'
/usr/bin/ld: LinearSeries.cpp:(.text+0x64c): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: LinearSeries.cpp:(.text+0x6b5): undefined reference to `ops_getintinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(ConstantSeries.o): in function `OPS_ConstantSeries()':
ConstantSeries.cpp:(.text+0x72c): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: ConstantSeries.cpp:(.text+0x7e1): undefined reference to `ops_getstring'
/usr/bin/ld: ConstantSeries.cpp:(.text+0x804): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: ConstantSeries.cpp:(.text+0x86d): undefined reference to `ops_getintinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(ModifiedNewton.o): in function `OPS_ModifiedNewton()':
ModifiedNewton.cpp:(.text+0x5ad): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: ModifiedNewton.cpp:(.text+0x5ba): undefined reference to `ops_getstring'
/usr/bin/ld: ModifiedNewton.cpp:(.text+0x6ad): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: ModifiedNewton.cpp:(.text+0x733): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(CTestNormDispIncr.o): in function `OPS_CTestNormDispIncr()':
CTestNormDispIncr.cpp:(.text+0xb9d): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: CTestNormDispIncr.cpp:(.text+0xbcc): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: CTestNormDispIncr.cpp:(.text+0xbd9): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: CTestNormDispIncr.cpp:(.text+0xc06): undefined reference to `ops_getintinput_'
/usr/bin/ld: CTestNormDispIncr.cpp:(.text+0xc1f): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: CTestNormDispIncr.cpp:(.text+0xc38): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(LoadControl.o): in function `OPS_LoadControlIntegrator()':
LoadControl.cpp:(.text+0xbfc): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: LoadControl.cpp:(.text+0xc1e): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: LoadControl.cpp:(.text+0xc59): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: LoadControl.cpp:(.text+0xd79): undefined reference to `ops_getintinput_'
/usr/bin/ld: LoadControl.cpp:(.text+0xd92): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(ForceBeamColumn3d.o): in function `OPS_ForceBeamColumn3d()':
ForceBeamColumn3d.cpp:(.text+0x18805): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: ForceBeamColumn3d.cpp:(.text+0x18813): undefined reference to `ops_getndm_'
/usr/bin/ld: ForceBeamColumn3d.cpp:(.text+0x1881a): undefined reference to `ops_getndf_'
/usr/bin/ld: ForceBeamColumn3d.cpp:(.text+0x18843): undefined reference to `ops_getintinput_'
/usr/bin/ld: ForceBeamColumn3d.cpp:(.text+0x18881): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: ForceBeamColumn3d.cpp:(.text+0x1888e): undefined reference to `ops_getstring'
/usr/bin/ld: ForceBeamColumn3d.cpp:(.text+0x188c8): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: ForceBeamColumn3d.cpp:(.text+0x188d7): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: ForceBeamColumn3d.cpp:(.text+0x18941): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: ForceBeamColumn3d.cpp:(.text+0x18955): undefined reference to `ops_getintinput_'
/usr/bin/ld: ForceBeamColumn3d.cpp:(.text+0x18969): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(LobattoBeamIntegration.o): in function `OPS_LobattoBeamIntegration(int&, ID&)':
LobattoBeamIntegration.cpp:(.text+0x675): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: LobattoBeamIntegration.cpp:(.text+0x69a): undefined reference to `ops_getintinput_'
/usr/bin/ld: LobattoBeamIntegration.cpp:(.text+0x6dd): undefined reference to `ops_getintinput_'
/usr/bin/ld: LobattoBeamIntegration.cpp:(.text+0x7c9): undefined reference to `ops_getintinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(LinearCrdTransf3d.o): in function `OPS_LinearCrdTransf3d()':
LinearCrdTransf3d.cpp:(.text+0x142e9): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: LinearCrdTransf3d.cpp:(.text+0x1430c): undefined reference to `ops_getintinput_'
/usr/bin/ld: LinearCrdTransf3d.cpp:(.text+0x14340): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: LinearCrdTransf3d.cpp:(.text+0x14391): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: LinearCrdTransf3d.cpp:(.text+0x1439f): undefined reference to `ops_getstring'
/usr/bin/ld: LinearCrdTransf3d.cpp:(.text+0x1442b): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: LinearCrdTransf3d.cpp:(.text+0x144c7): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: LinearCrdTransf3d.cpp:(.text+0x144d7): undefined reference to `ops_getdoubleinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(PlaneStressMaterial.o): in function `OPS_PlaneStress()':
PlaneStressMaterial.cpp:(.text+0x2d8e): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: PlaneStressMaterial.cpp:(.text+0x2db2): undefined reference to `ops_getintinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(PlateFiberMaterial.o): in function `OPS_PlateFiberMaterial()':
PlateFiberMaterial.cpp:(.text+0x24ce): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: PlateFiberMaterial.cpp:(.text+0x24f2): undefined reference to `ops_getintinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(BeamFiberMaterial.o): in function `OPS_BeamFiberMaterial()':
BeamFiberMaterial.cpp:(.text+0x2ede): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: BeamFiberMaterial.cpp:(.text+0x2efa): undefined reference to `ops_getintinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libOpenSees.a(BeamFiberMaterial2d.o): in function `OPS_BeamFiberMaterial2d()':
BeamFiberMaterial2d.cpp:(.text+0x399e): undefined reference to `OPS_GetNumRemainingInputArgs'
/usr/bin/ld: BeamFiberMaterial2d.cpp:(.text+0x39ba): undefined reference to `ops_getintinput_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libLapack.a(dgbtrs.o): in function `dgbtrs_':
dgbtrs.f:(.text+0x241): undefined reference to `dswap_'
/usr/bin/ld: dgbtrs.f:(.text+0x349): undefined reference to `dtbsv_'
/usr/bin/ld: dgbtrs.f:(.text+0x3fd): undefined reference to `dswap_'
/usr/bin/ld: dgbtrs.f:(.text+0x4f5): undefined reference to `dtbsv_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libLapack.a(dgetrs.o): in function `dgetrs_':
dgetrs.f:(.text+0x19b): undefined reference to `dtrsm_'
/usr/bin/ld: dgetrs.f:(.text+0x1e2): undefined reference to `dtrsm_'
/usr/bin/ld: dgetrs.f:(.text+0x23e): undefined reference to `dtrsm_'
/usr/bin/ld: dgetrs.f:(.text+0x285): undefined reference to `dtrsm_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libLapack.a(dgetrf.o): in function `dgetrf_':
dgetrf.f:(.text+0x393): undefined reference to `dtrsm_'
/usr/bin/ld: dgetrf.f:(.text+0x440): undefined reference to `dgemm_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libLapack.a(dgetf2.o): in function `dgetf2_':
dgetf2.f:(.text+0x181): undefined reference to `dswap_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libLapack.a(dgetri.o): in function `dgetri_':
dgetri.f:(.text+0x446): undefined reference to `dtrsm_'
/usr/bin/ld: dgetri.f:(.text+0x55a): undefined reference to `dgemm_'
/usr/bin/ld: dgetri.f:(.text+0x5f6): undefined reference to `dswap_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libLapack.a(dtrtri.o): in function `dtrtri_':
dtrtri.f:(.text+0x2ec): undefined reference to `dtrmm_'
/usr/bin/ld: dtrtri.f:(.text+0x33c): undefined reference to `dtrsm_'
/usr/bin/ld: dtrtri.f:(.text+0x525): undefined reference to `dtrmm_'
/usr/bin/ld: dtrtri.f:(.text+0x59c): undefined reference to `dtrsm_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libLapack.a(dtrti2.o): in function `dtrti2_':
dtrti2.f:(.text+0x1b3): undefined reference to `dtrmv_'
/usr/bin/ld: dtrti2.f:(.text+0x310): undefined reference to `dtrmv_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libLapack.a(dgbtrf.o): in function `dgbtrf_':
dgbtrf.f:(.text+0x462): undefined reference to `dswap_'
/usr/bin/ld: dgbtrf.f:(.text+0x629): undefined reference to `dswap_'
/usr/bin/ld: dgbtrf.f:(.text+0x684): undefined reference to `dswap_'
/usr/bin/ld: dgbtrf.f:(.text+0x9d6): undefined reference to `dtrsm_'
/usr/bin/ld: dgbtrf.f:(.text+0xab6): undefined reference to `dgemm_'
/usr/bin/ld: dgbtrf.f:(.text+0xb85): undefined reference to `dgemm_'
/usr/bin/ld: dgbtrf.f:(.text+0xc71): undefined reference to `dtrsm_'
/usr/bin/ld: dgbtrf.f:(.text+0xde0): undefined reference to `dgemm_'
/usr/bin/ld: dgbtrf.f:(.text+0xe92): undefined reference to `dgemm_'
/usr/bin/ld: dgbtrf.f:(.text+0xf02): undefined reference to `dswap_'
/usr/bin/ld: dgbtrf.f:(.text+0xfd2): undefined reference to `dswap_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libLapack.a(dlaswp.o): in function `dlaswp_':
dlaswp.f:(.text+0xb1): undefined reference to `dswap_'
/usr/bin/ld: dlaswp.f:(.text+0xe1): undefined reference to `dswap_'
/usr/bin/ld: dlaswp.f:(.text+0x11c): undefined reference to `dswap_'
/usr/bin/ld: /mnt/Data01/OpenSees/v330/lib/libLapack.a(dgbtf2.o):dgbtf2.f:(.text+0x36c): more undefined references to `dswap_' follow
collect2: error: ld returned 1 exit status

[GFiorillo]

I think I found the issue. In the 2.4.2 the only library for OpenSees was libOpenSees.a, in the 3.4.0 version there is an additional library libOpenSeesclCommands.a that was not included in my C++ makefile. I added it and the code was compiled.
Thank you anyway!