template class problem

[michael]

Hi All,

Not sure if this is a c++ issue or a compiler issue.

I have the following in a class:

template<class T>
bool Utility::getInp ut(T& i, T low, T up){
bool result = false;
if(cin >i){
if((i >= low)&&(i <= up)){
result = true;
}
} else {
cin.clear();
cin.ignore(1000 , '\n');
}
return result;
}

in another file and class I have :

Utility utility;
utility.getInpu t(sal, 0.0, 999999.99);
utility.getInpu t(sid, 0, 999999);

Now, if I put all this in one file it compiles no worries. But, if I compile
it as is i get an error from the linker:

[linker error] Undefined reference to 'bool
Utility::getInp ut<double>(doub le&, double, double)'

Why if the linker can't find the reference to 'bool
Utility::getInp ut<double>(doub le&, double, double)' does it not complain
about the (int&, int, int) reference that comes before it in the code? How
can I resolve the error? The only linker errors I've had before have been
related to not including files in the compile command, but this is something
else....

Thanks for your help.

Regards

Michael

[mliptak]

On Mar 28, 12:51 pm, "michael" <[e-mail] twrote:

Hi All,

Not sure if this is a c++ issue or a compiler issue.

I have the following in a class:

template<class T>
bool Utility::getInp ut(T& i, T low, T up){
bool result = false;
if(cin >i){
if((i >= low)&&(i <= up)){
result = true;
}
} else {
cin.clear();
cin.ignore(1000 , '\n');
}
return result;

}

in another file and class I have :

Utility utility;
utility.getInpu t(sal, 0.0, 999999.99);
utility.getInpu t(sid, 0, 999999);

Now, if I put all this in one file it compiles no worries. But, if I compile
it as is i get an error from the linker:

[linker error] Undefined reference to 'bool
Utility::getInp ut<double>(doub le&, double, double)'

Why if the linker can't find the reference to 'bool
Utility::getInp ut<double>(doub le&, double, double)' does it not complain
about the (int&, int, int) reference that comes before it in the code? How
can I resolve the error? The only linker errors I've had before have been
related to not including files in the compile command, but this is something
else....

Thanks for your help.

Regards

Michael

can you post a minimal testcase that compiles but does not link to
demonstrate your problem?
m.

[Alexander Block]

michael schrieb:

Hi All,

Not sure if this is a c++ issue or a compiler issue.

I have the following in a class:

template<class T>
bool Utility::getInp ut(T& i, T low, T up){
bool result = false;
if(cin >i){
if((i >= low)&&(i <= up)){
result = true;
}
} else {
cin.clear();
cin.ignore(1000 , '\n');
}
return result;
}

in another file and class I have :

Utility utility;
utility.getInpu t(sal, 0.0, 999999.99);
utility.getInpu t(sid, 0, 999999);

Now, if I put all this in one file it compiles no worries. But, if I compile
it as is i get an error from the linker:

[linker error] Undefined reference to 'bool
Utility::getInp ut<double>(doub le&, double, double)'

Why if the linker can't find the reference to 'bool
Utility::getInp ut<double>(doub le&, double, double)' does it not complain
about the (int&, int, int) reference that comes before it in the code? How
can I resolve the error? The only linker errors I've had before have been
related to not including files in the compile command, but this is something
else....

Thanks for your help.

Regards

Michael

Is the definition and implementation of this function inside the same
header? You have to put the definition into the same header or into
one that is included by this header.

[terminator]

On Mar 28, 2:51 pm, "michael" <[e-mail] twrote:

Hi All,

Not sure if this is a c++ issue or a compiler issue.

I have the following in a class:

template<class T>
bool Utility::getInp ut(T& i, T low, T up){
bool result = false;
if(cin >i){
if((i >= low)&&(i <= up)){
result = true;
}
} else {
cin.clear();
cin.ignore(1000 , '\n');
}
return result;

}

in another file and class I have :

Utility utility;
utility.getInpu t(sal, 0.0, 999999.99);
utility.getInpu t(sid, 0, 999999);

Now, if I put all this in one file it compiles no worries. But, if I compile
it as is i get an error from the linker:

[linker error] Undefined reference to 'bool
Utility::getInp ut<double>(doub le&, double, double)'

Why if the linker can't find the reference to 'bool
Utility::getInp ut<double>(doub le&, double, double)' does it not complain
about the (int&, int, int) reference that comes before it in the code? How
can I resolve the error? The only linker errors I've had before have been
related to not including files in the compile command, but this is something
else....

Thanks for your help.

Regards

Michael

The problem is not in the code.You seem to not know how to device
modular (multi-file projects) programming with C++ .Read the
documentation for your compiler.

[linker error] Undefined reference to 'bool
Utility::getInp ut<double>(doub le&, double, double)'

this means that you have refered to(called/used) an
identifier(func tion in this context) that the linker can not find in
any file.