undefined reference to template class member
I am getting an undefined reference to my Pairwise class after I attempt to run it with sample input. My Pairwise class was made in a headerfile, and I made a main function to pass in key and value as strings to format them as I'd like.
My expected output:
key:value
My headerfile:
#pragma once
#include<iostream>
using std::ostream; using std::cout; using std::endl;
#include<string>
using std::string;
#include<sstream>
using std::ostringstream;
template<typename K, typename V>
struct Pairwise {
K first;
V second;
Pairwise() = default;
Pairwise(K,V);
friend ostream& operator<<(ostream &out, const Pairwise &p){
out << p.first << ":" << p.second;
return out;
}
};
My main function:
#include "file.h"
#include<iostream>
using std::cout; using std::endl;
#include<sstream>
using std::ostringstream;
#include<string>
using std::string;
int main()
{
Pairwise<string,string> p("key", "value");
ostringstream oss;
oss<<p;
string example = oss.str();
cout << example << endl;
}
The error that I am getting:
/tmp/ccfv4iaY.o: In function `main':
main_program.cpp:(.text+0x8b): undefined reference to `Pairwise<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >::Pairwise(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)'
collect2: error: ld returned 1 exit status
c++
asked Nov 25 '18 at 3:28
DracepDracep
10010
add a comment |
I am getting an undefined reference to my Pairwise class after I attempt to run it with sample input. My Pairwise class was made in a headerfile, and I made a main function to pass in key and value as strings to format them as I'd like.
My expected output:
key:value
My headerfile:
#pragma once
#include<iostream>
using std::ostream; using std::cout; using std::endl;
#include<string>
using std::string;
#include<sstream>
using std::ostringstream;
template<typename K, typename V>
struct Pairwise {
K first;
V second;
Pairwise() = default;
Pairwise(K,V);
friend ostream& operator<<(ostream &out, const Pairwise &p){
out << p.first << ":" << p.second;
return out;
}
};
My main function:
#include "file.h"
#include<iostream>
using std::cout; using std::endl;
#include<sstream>
using std::ostringstream;
#include<string>
using std::string;
int main()
{
Pairwise<string,string> p("key", "value");
ostringstream oss;
oss<<p;
string example = oss.str();
cout << example << endl;
}
The error that I am getting:
/tmp/ccfv4iaY.o: In function `main':
main_program.cpp:(.text+0x8b): undefined reference to `Pairwise<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >::Pairwise(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)'
collect2: error: ld returned 1 exit status
c++
asked Nov 25 '18 at 3:28
DracepDracep
10010
3
You've declared aPairwiseconstructor taking two parameters, but you haven't actually implemented it. You are nevertheless trying to use it.
– Igor Tandetnik
Nov 25 '18 at 3:30
@IgorTandetnik Ah I see what you mean! How could I implement Pairwise constructor to print out key:value if you don't mind?
– Dracep
Nov 25 '18 at 3:38
add a comment |
I am getting an undefined reference to my Pairwise class after I attempt to run it with sample input. My Pairwise class was made in a headerfile, and I made a main function to pass in key and value as strings to format them as I'd like.
My expected output:
key:value
My headerfile:
#pragma once
#include<iostream>
using std::ostream; using std::cout; using std::endl;
#include<string>
using std::string;
#include<sstream>
using std::ostringstream;
template<typename K, typename V>
struct Pairwise {
K first;
V second;
Pairwise() = default;
Pairwise(K,V);
friend ostream& operator<<(ostream &out, const Pairwise &p){
out << p.first << ":" << p.second;
return out;
}
};
My main function:
#include "file.h"
#include<iostream>
using std::cout; using std::endl;
#include<sstream>
using std::ostringstream;
#include<string>
using std::string;
int main()
{
Pairwise<string,string> p("key", "value");
ostringstream oss;
oss<<p;
string example = oss.str();
cout << example << endl;
}
The error that I am getting:
/tmp/ccfv4iaY.o: In function `main':
main_program.cpp:(.text+0x8b): undefined reference to `Pairwise<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >::Pairwise(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)'
collect2: error: ld returned 1 exit status
c++
asked Nov 25 '18 at 3:28
DracepDracep
10010
I am getting an undefined reference to my Pairwise class after I attempt to run it with sample input. My Pairwise class was made in a headerfile, and I made a main function to pass in key and value as strings to format them as I'd like.
My expected output:
key:value
My headerfile:
#pragma once
#include<iostream>
using std::ostream; using std::cout; using std::endl;
#include<string>
using std::string;
#include<sstream>
using std::ostringstream;
template<typename K, typename V>
struct Pairwise {
K first;
V second;
Pairwise() = default;
Pairwise(K,V);
friend ostream& operator<<(ostream &out, const Pairwise &p){
out << p.first << ":" << p.second;
return out;
}
};
My main function:
#include "file.h"
#include<iostream>
using std::cout; using std::endl;
#include<sstream>
using std::ostringstream;
#include<string>
using std::string;
int main()
{
Pairwise<string,string> p("key", "value");
ostringstream oss;
oss<<p;
string example = oss.str();
cout << example << endl;
}
The error that I am getting:
/tmp/ccfv4iaY.o: In function `main':
main_program.cpp:(.text+0x8b): undefined reference to `Pairwise<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >::Pairwise(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)'
collect2: error: ld returned 1 exit status
c++
c++
asked Nov 25 '18 at 3:28
DracepDracep
10010
asked Nov 25 '18 at 3:28
DracepDracep
10010
asked Nov 25 '18 at 3:28
DracepDracep
10010
asked Nov 25 '18 at 3:28
DracepDracep
10010
asked Nov 25 '18 at 3:28
DracepDracep
10010
10010
3
You've declared aPairwiseconstructor taking two parameters, but you haven't actually implemented it. You are nevertheless trying to use it.
– Igor Tandetnik
Nov 25 '18 at 3:30
@IgorTandetnik Ah I see what you mean! How could I implement Pairwise constructor to print out key:value if you don't mind?
– Dracep
Nov 25 '18 at 3:38
add a comment |
3
You've declared aPairwiseconstructor taking two parameters, but you haven't actually implemented it. You are nevertheless trying to use it.
– Igor Tandetnik
Nov 25 '18 at 3:30
@IgorTandetnik Ah I see what you mean! How could I implement Pairwise constructor to print out key:value if you don't mind?
– Dracep
Nov 25 '18 at 3:38
3
3
You've declared a
Pairwise constructor taking two parameters, but you haven't actually implemented it. You are nevertheless trying to use it.– Igor Tandetnik
Nov 25 '18 at 3:30
You've declared a
Pairwise constructor taking two parameters, but you haven't actually implemented it. You are nevertheless trying to use it.– Igor Tandetnik
Nov 25 '18 at 3:30
@IgorTandetnik Ah I see what you mean! How could I implement Pairwise constructor to print out key:value if you don't mind?
– Dracep
Nov 25 '18 at 3:38
@IgorTandetnik Ah I see what you mean! How could I implement Pairwise constructor to print out key:value if you don't mind?
– Dracep
Nov 25 '18 at 3:38
add a comment |
1 Answer
1
active
oldest
votes
Your template contains a declaration for Pairwise(K,V);, but it is never defined / implemented anywhere.
You need to add the definition in the same (or another) header file. To verify, replace the ; by {}, and the linker error should be gone: Pairwise(K,V) {} (it won't work but it will compile and link fine).
answered Nov 25 '18 at 3:33
AganjuAganju
5,1641721
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Your template contains a declaration for Pairwise(K,V);, but it is never defined / implemented anywhere.
You need to add the definition in the same (or another) header file. To verify, replace the ; by {}, and the linker error should be gone: Pairwise(K,V) {} (it won't work but it will compile and link fine).
answered Nov 25 '18 at 3:33
AganjuAganju
5,1641721
add a comment |
Your template contains a declaration for Pairwise(K,V);, but it is never defined / implemented anywhere.
You need to add the definition in the same (or another) header file. To verify, replace the ; by {}, and the linker error should be gone: Pairwise(K,V) {} (it won't work but it will compile and link fine).
answered Nov 25 '18 at 3:33
AganjuAganju
5,1641721
add a comment |
Your template contains a declaration for Pairwise(K,V);, but it is never defined / implemented anywhere.
You need to add the definition in the same (or another) header file. To verify, replace the ; by {}, and the linker error should be gone: Pairwise(K,V) {} (it won't work but it will compile and link fine).
answered Nov 25 '18 at 3:33
AganjuAganju
5,1641721
Your template contains a declaration for Pairwise(K,V);, but it is never defined / implemented anywhere.
You need to add the definition in the same (or another) header file. To verify, replace the ; by {}, and the linker error should be gone: Pairwise(K,V) {} (it won't work but it will compile and link fine).
answered Nov 25 '18 at 3:33
AganjuAganju
5,1641721
answered Nov 25 '18 at 3:33
AganjuAganju
5,1641721
answered Nov 25 '18 at 3:33
AganjuAganju
5,1641721
answered Nov 25 '18 at 3:33
AganjuAganju
5,1641721
5,1641721
add a comment |
add a comment |
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3
You've declared a
Pairwiseconstructor taking two parameters, but you haven't actually implemented it. You are nevertheless trying to use it.– Igor Tandetnik
Nov 25 '18 at 3:30
@IgorTandetnik Ah I see what you mean! How could I implement Pairwise constructor to print out key:value if you don't mind?
– Dracep
Nov 25 '18 at 3:38