
make: Entering directory `/home/richel/Projects/Test/CppLinkErrorUndefinedReferenceToSqrt-build-desktop-Qt_4_8_3_in_PATH__System__Release'

gcc -c -x c -O2 -Wall -W -D_REENTRANT -DQT_WEBKIT -DQT_NO_DEBUG -I/usr/share/qt4/mkspecs/linux-g++ -I../CppLinkErrorUndefinedReferenceToSqrt -I/usr/include/qt4 -I/opt/NAG/cll3a09dgl/include -I. -I../CppLinkErrorUndefinedReferenceToSqrt -I. -o main.o ../CppLinkErrorUndefinedReferenceToSqrt/main.cpp

g++ -Wl,-O1 -o CppLinkErrorUndefinedReferenceToSqrt main.o    -L/usr/lib/i386-linux-gnu -L/opt/NAG/cll3a09dgl/lib -lnagc_nag -lpthread 

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `sqrt'

make: Leaving directory `/home/richel/Projects/Test/CppLinkErrorUndefinedReferenceToSqrt-build-desktop-Qt_4_8_3_in_PATH__System__Release'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `floor'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `ceil'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `cosh'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `expm1f'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `tan'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `tanh'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `powf'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `log'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `atan'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `expm1'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `sinh'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `fmod'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `exp'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `sin'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `rint'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `pow'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `atan2'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `cos'

/opt/NAG/cll3a09dgl/lib/libnagc_nag.so: undefined reference to `log10'

collect2: error: ld returned 1 exit status

make: *** [CppLinkErrorUndefinedReferenceToSqrt] Error 1

11:11:40: The process "/usr/bin/make" exited with code 2.

Error while building/deploying project CppLinkErrorUndefinedReferenceToSqrt (target: Desktop)

When executing step 'Make'

Background

This link error occurred when

compiling to C (see How to use Qt Creator to compile C code?)
using the NAG C library

The most common solution to this link error would be to add the following line to your Qt project file:


LIBS += -lm

In this case, however, this did not work.

Technical facts

Application type(s)

Desktop application

Operating system(s) or programming environment(s)

Lubuntu 12.10 (quantal)

IDE(s):

Qt Creator 2.5.2

Project type:

Console application

C++ standard:

C: How to use Qt Creator to compile C code?

Compiler(s):

G++ 4.7.2

Libraries used:

STL: GNU ISO C++ Library, version 4.7.2

Qt project file: CppLinkErrorUndefinedReferenceToSqrt.pro


QT       -= core gui



INCLUDEPATH += /opt/NAG/cll3a09dgl/include



LIBS += -L/opt/NAG/cll3a09dgl/lib -lnagc_nag



#Compile with GNU C compiler

QMAKE_CXX = gcc

QMAKE_CXXFLAGS = -x c



CONFIG   += console

CONFIG   -= app_bundle

TEMPLATE = app

SOURCES += main.cpp

main.cpp


#include <math.h>

#include <nag.h>

#include <nag_stdlib.h>



///C code that is invalid C++ code

struct template

{

    int new;

    struct template* class;

};



void test()

{

  struct template t;

  t.new += 1;

  t.class = 0;

}





/* For C compiler */

int main(void)

{

  char * s = 0;

  s = NAG_ALLOC(31,char);

  if (!s)

  {

    /* ... */

    return 1;

  }

  /* ... */

  NAG_FREE(s);

  return 0;

}

Solution

Add the following two lines to your project file:


QMAKE_LFLAGS += -lm

LIBS += -lm

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(C++) link error: undefined reference to 'sqrt'

Background

Technical facts

Qt project file: CppLinkErrorUndefinedReferenceToSqrt.pro

main.cpp

Solution