LNK2019: unresolved external symbol but I have coded the function - c++

Question

Can somebody help me with this? I'm using Visual Studio 2010
I'm getting this message and I don't know how to solve this.
1> Generating Code...
1>dct.obj : error LNK2019: unresolved external symbol "public:
__thiscall Amostras::Amostras(class std::basic_string,class std::allocator >)"
(??0Amostras##QAE#V?$basic_string#DU?$char_traits#D#std##V?$allocator#D#2##std###Z)
referenced in function _main
1>C:\Users\redneck\documents\visual studio
2010\Projects\dct\Debug\dct.exe : fatal error LNK1120: 1 unresolved
externals
Here is some of the *.cpp file:
class Amostras {
public:
int original[10][257];
int idct[10][257];
float dct[10][257];
int grupos;
Amostras::Amostras(void)
{
for (int i=0;i<10;i++)
{
this->original[i][0]=0;
this->dct[i][0]=0.0;
this->idct[i][0]=0;
}
this->grupos=0;
}
Amostras::Amostras(string arquivo)
{
int n_samples=0,linha=0,coluna=0;
int cont;
..
and here is the *.h
class Amostras {
public:
int original[10][257];
int idct[10][257];
float dct[10][257];
int grupos;
Amostras::Amostras();
Amostras::Amostras(string arquivo);
void Amostras::mostra(void);
};
main
int main(void)
{
Amostras *amostra = new Amostras("in.txt");
dct(amostra,0);
show(amostra,0);
amostra->mostra();
return 0;
}
hope it helps, i'm running out of options here :(
Solution:
So what I did was just putting the class just in *.h and then including the *.h in the class *.cpp that only has the methods and functions of that class. It worked!

Answer 1

This linker error usually means that you have prototyped a function but forgotten to define it. Make sure that you have implemented the function
Amostras::Amostras(string arg);
somewhere, and that when you were linking your code that the object file containing that implementation was linked in.
Hope this helps!

Answer 2

you forgot to define the Amostras::Amostras(string arg);
though declared in your *.h file
Amostras::Amostras(string arg)
{
}
copy the above code in your *.cpp file
OR
you can also do this by commenting the line from your *.h file.
//Amostras::Amostras(string arg);
whoa! do you have a *.h file ? if you are working in only *.cpp then lemme know.