奇怪的未定义引用..错误

时间：2011-06-15 18:50:05

标签： c compiler-errors fixed-point

我正在尝试使用定点数学库进行实验，我发现on wikipedia并从google code下载了它。我尝试通过将以下main.c文件添加到源代码并将整个事件重新编译为可执行文件来编译一个简单的示例项目。

问题
gcc （我实际上正在使用codeblocks v1.0）抱怨未定义的函数引用 i really think the library defines。 某些功能正常工作其他功能会生成'未定义的引用错误'，例如，这是我尝试添加到源文件的main.c文件。

#include<stdio.h>
#include "fixmath.h"
int main()
{
    float num1=6.25f;
    float num2=2.567f;

    fix16_t numfix1=fix16_from_float(num1);
    fix16_t numfix2=fix16_from_float(num2);

    //try out arithmetic on the fixed numbers

    fix16_t simpleAdd= fix16_add(numfix1, numfix2);//(this works !!)no error 

    fix16_t product= fix16_smul(numfix1,numfix2);//undefined reference to 'fix16_smul'
    fix16_t quotient=fix16_sdiv(numfix1,numfix2);//undefined reference to 'fix16_sdiv'
    fix16_t sum=fix16_sadd(numfix1,numfix2);//undefined reference to 'fix16_sadd'
    fix16_t difference=fix16_ssub(numfix1,numfix2);//undefined reference to ....

    //print out the results
    printf("the product of %f * %f =%f \n",num1,num2,fix16_to_float(product));
    printf("the quotient of %f and %f =%f \n",num1,num2,fix16_to_float(quotient));
    printf("the sum of %f + %f =%f \n",num1,num2,fix16_to_float(sum));
    printf("the difference of %f - %f =%f \n",num1,num2,fix16_to_float(difference));

    //system("pause")
    printf("please press any key to continue ...\n");
    getchar();

}



EDIT3：
//显示makefile和build log 

//build log
Project   : libfixmath
Compiler  : GNU GCC Compiler (called directly)
Directory : C:\libfixmath\
--------------------------------------------------------------------------------
Switching to target: dbg
Linking console executable: fixmathexample.exe
obj\dbg\main.o: In function `main':
C:/libfixmath/main.c:14: undefined reference to `fix16_smul'
C:/libfixmath/main.c:15: undefined reference to `fix16_sdiv'
C:/libfixmath/main.c:16: undefined reference to `fix16_sadd'
obj\dbg\main.o: In function `fix16_ssub':
C:/libfixmath/fix16.h:51: undefined reference to `fix16_sadd'
collect2: ld returned 1 exit status
Process terminated with status 1 (0 minutes, 0 seconds)
4 errors, 0 warnings

//导出的make文件

###############################################################################
# Makefile automatically generated by Code::Blocks IDE                        #
###############################################################################

# Project:          libfixmath
# Project filename: C:\libfixmath\libfixmath.cbp
# Compiler used:    GNU GCC Compiler

### Variables used in this Makefile
dbg_CC=mingw32-gcc.exe
dbg_CPP=mingw32-g++.exe
dbg_LD=mingw32-g++.exe
dbg_LIB=ar.exe
dbg_RESCOMP=windres.exe
rel_CC=mingw32-gcc.exe
rel_CPP=mingw32-g++.exe
rel_LD=mingw32-g++.exe
rel_LIB=ar.exe
rel_RESCOMP=windres.exe

### Compiler/linker options
dbg_GLOBAL_CFLAGS=
dbg_PROJECT_CFLAGS= -DFIXMATH_NO_CACHE -DFIXMATH_NO_64BIT
dbg_GLOBAL_LDFLAGS=
dbg_PROJECT_LDFLAGS=
dbg_GLOBAL_INCS= -IC:/Program\ Files/CodeBlocks/include
dbg_PROJECT_INCS=
dbg_GLOBAL_LIBDIRS= -LC:/Program\ Files/CodeBlocks/lib
dbg_PROJECT_LIBDIRS= -LC:/libfixmath/lib
dbg_GLOBAL_LIBS=
dbg_PROJECT_LIBS= C:\libfixmath\lib\libfixmath.a
rel_GLOBAL_CFLAGS=
rel_PROJECT_CFLAGS= -DFIXMATH_NO_CACHE -DFIXMATH_NO_64BIT
rel_GLOBAL_LDFLAGS=
rel_PROJECT_LDFLAGS=
rel_GLOBAL_INCS= -IC:/Program\ Files/CodeBlocks/include
rel_PROJECT_INCS=
rel_GLOBAL_LIBDIRS= -LC:/Program\ Files/CodeBlocks/lib
rel_PROJECT_LIBDIRS= -LC:/libfixmath/lib
rel_GLOBAL_LIBS=
rel_PROJECT_LIBS= C:\libfixmath\lib\libfixmath.a

### Targets compiler flags
dbg_CFLAGS= $(dbg_PROJECT_CFLAGS) -Wall -g $(dbg_GLOBAL_CFLAGS)
rel_CFLAGS= $(rel_PROJECT_CFLAGS) -fexpensive-optimizations -O3 -Wall -fomit-frame-pointer $(rel_GLOBAL_CFLAGS)

### Targets linker flags
dbg_LDFLAGS= $(dbg_PROJECT_LDFLAGS) $(dbg_GLOBAL_LDFLAGS)
rel_LDFLAGS= $(rel_PROJECT_LDFLAGS) -s $(rel_GLOBAL_LDFLAGS)

### Targets include directories
dbg_INCS= $(dbg_PROJECT_INCS) $(dbg_GLOBAL_INCS)
rel_INCS= $(rel_PROJECT_INCS) $(rel_GLOBAL_INCS)

### Targets library directories
dbg_LIBDIRS= $(dbg_PROJECT_LIBDIRS) $(dbg_GLOBAL_LIBDIRS)
rel_LIBDIRS= $(rel_PROJECT_LIBDIRS) $(rel_GLOBAL_LIBDIRS)

### Targets libraries
dbg_LIBS= $(dbg_PROJECT_LIBS) $(dbg_GLOBAL_LIBS)
rel_LIBS= $(rel_PROJECT_LIBS) $(rel_GLOBAL_LIBS)

###############################################################################
#         You shouldn't need to modify anything beyond this point             #
###############################################################################

### Resources used in this Makefile
dbg_RESOURCE=

### Objects used in this Makefile
dbg_OBJS=obj/dbg/main.o 
dbg_LINKOBJS=$(dbg_OBJS)
dbg_DEPS=.deps/main.d 
rel_OBJS=obj/rel/main.o 
rel_LINKOBJS=$(rel_OBJS)
rel_DEPS=.deps/main.d 

### The targets of this project
dbg_BIN=fixmathexample.exe
rel_BIN=fixmathexample

.PHONY: all all-before all-custom all-after clean clean-custom distclean distclean-custom depend_dbg dbg-before dbg-after depend_rel rel-before rel-after 

all: all-before dbg rel all-after


dist:
    @zip libfixmath.cbp.zip libfixmath.cbp Makefile Makefile fix16.c fix16.h fix16_exp.c fix16_sqrt.c fix16_trig.c fixmath.h fract32.c fract32.h int64.h main.c uint32.c uint32.h 

clean_dbg:
    @echo Cleaning target "dbg"...
    @$(RM) $(dbg_BIN) $(dbg_OBJS) $(dbg_RESOURCE) 

distclean_dbg:
    @echo Dist-cleaning target "dbg"...
    @$(RM) $(dbg_BIN) $(dbg_OBJS) $(dbg_DEPS) $(dbg_RESOURCE) 

clean_rel:
    @echo Cleaning target "rel"...
    @$(RM) $(rel_BIN) $(rel_OBJS) $(rel_RESOURCE) 

distclean_rel:
    @echo Dist-cleaning target "rel"...
    @$(RM) $(rel_BIN) $(rel_OBJS) $(rel_DEPS) $(rel_RESOURCE) 

clean: clean_dbg clean_rel 

distclean: distclean_dbg distclean_rel 

depend_dbg_DIRS:
    -@if not exist ".deps\." mkdir ".deps"

depend_dbg: depend_dbg_DIRS $(dbg_DEPS)

depend_rel_DIRS:
    -@if not exist ".deps\." mkdir ".deps"

depend_rel: depend_rel_DIRS $(rel_DEPS)

depend: depend_dbg depend_rel

dbg_DIRS:
    -@if not exist "obj\." mkdir "obj"
    -@if not exist "obj\dbg\." mkdir "obj\dbg"

dbg: depend_dbg dbg_DIRS dbg-before $(dbg_BIN) dbg-after

$(dbg_BIN): $(dbg_LINKOBJS) $(dbg_RESOURCE)
    @echo Linking executable "fixmathexample.exe"...
    @$(dbg_LD) $(dbg_LIBDIRS) -o $(dbg_BIN) $(dbg_LINKOBJS) $(dbg_RESOURCE) $(dbg_LDFLAGS) $(dbg_LIBS)

rel_DIRS:
    -@if not exist "obj\." mkdir "obj"
    -@if not exist "obj\rel\." mkdir "obj\rel"

rel: depend_rel rel_DIRS rel-before $(rel_BIN) rel-after

$(rel_BIN): $(rel_LINKOBJS) $(rel_RESOURCE)
    @echo Linking executable "fixmathexample"...
    @$(rel_LD) $(rel_LIBDIRS) -o $(rel_BIN) $(rel_LINKOBJS) $(rel_RESOURCE) $(rel_LDFLAGS) $(rel_LIBS)


.deps/main.d: main.c
    @echo Calculating dependencies for "main.c"...
    @$(dbg_CC) -MM $(dbg_CFLAGS) -MF .deps/main.d -MT obj/dbg/main.o,obj/rel/main.o $(dbg_INCS) main.c

obj/dbg/main.o: .deps/main.d
    @echo Compiling "main.c"...
    @$(dbg_CC) $(dbg_CFLAGS) $(dbg_INCS) -c main.c -o obj/dbg/main.o


obj/rel/main.o: main.c
    @echo Compiling "main.c"...
    @$(rel_CC) $(rel_CFLAGS) $(rel_INCS) -c main.c -o obj/rel/main.o

2 个答案:

答案 0 :(得分：3)

您确定已将链接添加到库中吗？可能工作的是在头文件中定义的内联函数，因此您有自己的定义，其他的定义在.lib文件中，您需要链接它们。

答案 1 :(得分：1)

你是对的，图书馆确实提供了这些，但“未定义的引用”是一个链接器错误;您必须将库链接到编译的目标代码。单独包含标题是不够的，它只包含库提供的符号的声明。

我想像Code :: Blocks'项目经理有一个用于指定其他库的条目。

fix16_add适用于此情况，因为它在头文件中完全定义为inline代码。

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