VC出现error LNK2005 错误应该怎么办??

--------------------Configuration: abc - Win32 Debug--------------------
Linking...
main.obj : error LNK2005: "double __cdecl AVE(double,double,double)" (?AVE@@YANNNN@Z) already defined in abc.obj
Debug/abc.exe : fatal error LNK1169: one or more multiply defined symbols found
执行 link.exe 时出错.

abc.exe - 1 error(s), 0 warning(s)

---main.cpp---

#include <iomanip.h>
#include "abc.cpp"
void main()
{
double a,b,c;
double averageValue;
a=2;b=3;c=4;
averageValue=AVE(a,b,c);
cout<<"averageValue:"<<averageValue<<endl;
averageValue=AVE(a,b+1,c+2);
cout<<"averageValue:"<<averageValue<<endl;
}

---abc.cpp---

double AVE(double x,double y,double z)
{
return (x+y+z)/3；
}

---

在abc.h文件中写函数AVE的声明，然后纯枯握在main.cpp中#include "abc.h"败扰

或者

在工程中排除掉abc.cpp文做庆件

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