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This is my code. It's to practice using templates.

Header

#ifndef H_rectangleType #define H_rectangleType #include <iostream> using namespace std; namespace Rectangle{ template <class myType> class rectangleType { //Overload the stream insertion and extraction operators friend ostream& operator << (ostream&, const rectangleType &); friend istream& operator >> (istream&, rectangleType &); public: void setDimension(myType l, myType w); myType getLength() const; myType getWidth() const; myType area() const; myType perimeter() const; void print() const; rectangleType<myType> operator+(const rectangleType<myType>&) const; //Overload the operator + rectangleType<myType> operator*(const rectangleType<myType>&) const; //Overload the operator * bool operator==(const myType&) const; //Overload the operator == bool operator!=(const myType&) const; //Overload the operator != rectangleType(); rectangleType(myType l, myType w); private: myType length; myType width; }; } #endif

Member Definitions

#include <iostream> #include "rectangleType.h" using namespace std; namespace Rectangle{ template <class myType> void rectangleType<myType>::setDimension(myType l, myType w) { if (l >= 0) length = l; else length = 0; if (w >= 0) width = w; else width = 0; } template <class myType> myType rectangleType<myType>::getLength() const { return length; } template <class myType> myType rectangleType<myType>::getWidth()const { return width; } template <class myType> myType rectangleType<myType>::area() const { return length * width; } template <class myType> myType rectangleType<myType>::perimeter() const { return 2 * (length + width); } template <class myType> void rectangleType<myType>::print() const { cout << "Length = " << length << "; Width = " << width; } template <class myType> rectangleType<myType>::rectangleType(myType l, myType w) { setDimension(l, w); } template <class myType> rectangleType<myType>::rectangleType() { length = 0; width = 0; } template <class myType> rectangleType<myType> rectangleType<myType>::operator+ (const rectangleType<myType>& rectangle) const { rectangleType<myType> tempRect; tempRect.length = length + rectangle.length; tempRect.width = width + rectangle.width; return tempRect; } template <class myType> rectangleType<myType> rectangleType<myType>::operator* (const rectangleType<myType>& rectangle) const { rectangleType<myType> tempRect; tempRect.length = length * rectangle.length; tempRect.width = width * rectangle.width; return tempRect; } template <class myType> bool rectangleType<myType>::operator== (const myType& rectangle) const { return (length == rectangle.length && width == rectangle.width); } template <class myType> bool rectangleType<myType>::operator!= (const myType& rectangle) const { return (length != rectangle.length || width != rectangle.width); } template <class myType2> ostream& operator << (ostream& osObject, const rectangleType<myType2>& rectangle) { osObject << "Length = " << rectangle.length << "; Width = " << rectangle.width; return osObject; } template <class myType2> istream& operator >> (istream& isObject, rectangleType<myType2>& rectangle) { isObject >> rectangle.length >> rectangle.width; return isObject; } }

Main

#include <iostream> //Line 1 #include "rectangleType.h" //Line 2 using namespace std; //Line 3 using namespace Rectangle; int main() //Line 4 { //Line 5 cout << "Enter the type of your Rectangle.\n1. int\n2. double\n3. float"; rectangleType<double> myRectangle(23, 45); //Line 6 int int1 = 1; int double1 = 2; int float1 = 3; int temp= 0; cin >> temp; //Line 7 if(temp == int1) { rectangleType<int> myRectangle(23, 45); rectangleType<int> yourRectangle; cout << "Line 8: myRectangle: " << myRectangle << endl; cout << "Line 9: Enter the length and width " <<"of a rectangle: "; cin >> yourRectangle; cout << endl; cout << "Line 12: yourRectangle: " << yourRectangle << endl; cout << "Line 13: myRectangle + yourRectangle: " << myRectangle + yourRectangle << endl; cout << "Line 14: myRectangle * yourRectangle: " << myRectangle * yourRectangle << endl; } if(temp == double1) { rectangleType<double> myRectangle(23, 45); rectangleType<double> yourRectangle; cout << "Line 8: myRectangle: " << myRectangle << endl; cout << "Line 9: Enter the length and width " <<"of a rectangle: "; cin >> yourRectangle; cout << endl; cout << "Line 12: yourRectangle: " << yourRectangle << endl; cout << "Line 13: myRectangle + yourRectangle: " << myRectangle + yourRectangle << endl; cout << "Line 14: myRectangle * yourRectangle: " << myRectangle * yourRectangle << endl; } if(temp == float1) { rectangleType<float> myRectangle(23, 45); rectangleType<float> yourRectangle; cout << "Line 8: myRectangle: " << myRectangle << endl; cout << "Line 9: Enter the length and width " <<"of a rectangle: "; cin >> yourRectangle; cout << endl; cout << "Line 12: yourRectangle: " << yourRectangle << endl; cout << "Line 13: myRectangle + yourRectangle: " << myRectangle + yourRectangle << endl; cout << "Line 14: myRectangle * yourRectangle: " << myRectangle * yourRectangle << endl; } return 0;

}

Here,I'm getting these errors

1>testOpOverLoadClass.obj : error LNK2019: unresolved external symbol "public: class Rectangle::rectangleType<float> __thiscall Rectangle::rectangleType<float>::operator*(class Rectangle::rectangleType<float> const &)const " (??D?$rectangleType@M@Rectangle@@QBE?AV01@ABV01@@Z) referenced in function _main 1>testOpOverLoadClass.obj : error LNK2019: unresolved external symbol "public: class Rectangle::rectangleType<float> __thiscall Rectangle::rectangleType<float>::operator+(class Rectangle::rectangleType<float> const &)const " (??H?$rectangleType@M@Rectangle@@QBE?AV01@ABV01@@Z) referenced in function _main 1>testOpOverLoadClass.obj : error LNK2019: unresolved external symbol "class std::basic_istream<char,struct std::char_traits<char> > & __cdecl Rectangle::operator>>(class std::basic_istream<char,struct std::char_traits<char> > &,class Rectangle::rectangleType<float> &)" (??5Rectangle@@YAAAV?$basic_istream@DU?$char_traits@D@std@@@std@@AAV12@AAV?$rectangleType@M@0@@Z) referenced in function _main 1>testOpOverLoadClass.obj : error LNK2019: unresolved external symbol "class std::basic_ostream<char,struct std::char_traits<char> > & __cdecl Rectangle::operator<<(class std::basic_ostream<char,struct std::char_traits<char> > &,class Rectangle::rectangleType<float> const &)" (??6Rectangle@@YAAAV?$basic_ostream@DU?$char_traits@D@std@@@std@@AAV12@ABV?$rectangleType@M@0@@Z) referenced in function _main 1>testOpOverLoadClass.obj : error LNK2019: unresolved external symbol "public: __thiscall Rectangle::rectangleType<float>::rectangleType<float>(void)" (??0?$rectangleType@M@Rectangle@@QAE@XZ) referenced in function _main 1>testOpOverLoadClass.obj : error LNK2019: unresolved external symbol "public: __thiscall Rectangle::rectangleType<float>::rectangleType<float>(float,float)" (??0?$rectangleType@M@Rectangle@@QAE@MM@Z) referenced in function _main 1>testOpOverLoadClass.obj : error LNK2019: unresolved external symbol "public: class Rectangle::rectangleType<double> __thiscall Rectangle::rectangleType<double>::operator*(class Rectangle::rectangleType<double> const &)const " (??D?$rectangleType@N@Rectangle@@QBE?AV01@ABV01@@Z) referenced in function _main 1>testOpOverLoadClass.obj : error LNK2019: unresolved external symbol "public: class Rectangle::rectangleType<double> __thiscall Rectangle::rectangleType<double>::operator+(class Rectangle::rectangleType<double> const &)const " (??H?$rectangleType@N@Rectangle@@QBE?AV01@ABV01@@Z) referenced in function _main 1>testOpOverLoadClass.obj : error LNK2019: unresolved external symbol "class std::basic_istream<char,struct std::char_traits<char> > & __cdecl Rectangle::operator>>(class std::basic_istream<char,struct std::char_traits<char> > &,class Rectangle::rectangleType<double> &)" (??5Rectangle@@YAAAV?$basic_istream@DU?$char_traits@D@std@@@std@@AAV12@AAV?$rectangleType@N@0@@Z) referenced in function _main 1>testOpOverLoadClass.obj : error LNK2019: unresolved external symbol "class std::basic_ostream<char,struct std::char_traits<char> > & __cdecl Rectangle::operator<<(class std::basic_ostream<char,struct std::char_traits<char> > &,class Rectangle::rectangleType<double> const &)" (??6Rectangle@@YAAAV?$basic_ostream@DU?$char_traits@D@std@@@std@@AAV12@ABV?$rectangleType@N@0@@Z) referenced in function _main 1>testOpOverLoadClass.obj : error LNK2019: unresolved external symbol "public: __thiscall Rectangle::rectangleType<double>::rectangleType<double>(void)" (??0?$rectangleType@N@Rectangle@@QAE@XZ) referenced in function _main 1>testOpOverLoadClass.obj : error LNK2019: unresolved external symbol "public: class Rectangle::rectangleType<int> __thiscall Rectangle::rectangleType<int>::operator*(class Rectangle::rectangleType<int> const &)const " (??D?$rectangleType@H@Rectangle@@QBE?AV01@ABV01@@Z) referenced in function _main 1>testOpOverLoadClass.obj : error LNK2019: unresolved external symbol "public: class Rectangle::rectangleType<int> __thiscall Rectangle::rectangleType<int>::operator+(class Rectangle::rectangleType<int> const &)const " (??H?$rectangleType@H@Rectangle@@QBE?AV01@ABV01@@Z) referenced in function _main 1>testOpOverLoadClass.obj : error LNK2019: unresolved external symbol "class std::basic_istream<char,struct std::char_traits<char> > & __cdecl Rectangle::operator>>(class std::basic_istream<char,struct std::char_traits<char> > &,class Rectangle::rectangleType<int> &)" (??5Rectangle@@YAAAV?$basic_istream@DU?$char_traits@D@std@@@std@@AAV12@AAV?$rectangleType@H@0@@Z) referenced in function _main 1>testOpOverLoadClass.obj : error LNK2019: unresolved external symbol "class std::basic_ostream<char,struct std::char_traits<char> > & __cdecl Rectangle::operator<<(class std::basic_ostream<char,struct std::char_traits<char> > &,class Rectangle::rectangleType<int> const &)" (??6Rectangle@@YAAAV?$basic_ostream@DU?$char_traits@D@std@@@std@@AAV12@ABV?$rectangleType@H@0@@Z) referenced in function _main 1>testOpOverLoadClass.obj : error LNK2019: unresolved external symbol "public: __thiscall Rectangle::rectangleType<int>::rectangleType<int>(void)" (??0?$rectangleType@H@Rectangle@@QAE@XZ) referenced in function _main 1>testOpOverLoadClass.obj : error LNK2019: unresolved external symbol "public: __thiscall Rectangle::rectangleType<int>::rectangleType<int>(int,int)" (??0?$rectangleType@H@Rectangle@@QAE@HH@Z) referenced in function _main 1>testOpOverLoadClass.obj : error LNK2019: unresolved external symbol "public: __thiscall Rectangle::rectangleType<double>::rectangleType<double>(double,double)" (??0?$rectangleType@N@Rectangle@@QAE@NN@Z) referenced in function _main 1>C:\Users\jr\Documents\Visual Studio 2010\Projects\CMPE 126\Lab 2\Debug\Lab 2.exe : fatal error LNK1120: 18 unresolved externals

I cant seem to make what these errors mean. Thanks inadvance

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  • ... and once again, there is using namespace std; in the beginning of a header file. Commented Feb 11, 2013 at 11:16
  • @LihO Do you not need the "using namespace std;" my professor gave us the basic code and we had to edit it Commented Feb 12, 2013 at 0:23
  • It's considered a bad practice to have it in a header file. Have a look at this answer: stackoverflow.com/questions/1265039/using-std-namespace/… Commented Feb 12, 2013 at 8:02

2 Answers 2

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2

You can't separate definition and implementation for templated classes. You have to put the functions in the header file as well.

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2 Comments

Actually you can separate them. You have to make sure they have been instantiated though.
@JoachimPileborg after putting the two codes together, i'm still getting a couple of error LNK2019 errors. I know it's a long code but is the formatting correct?
1

Your template function definitions should be visible by the calling code.

Inline them.

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3 Comments

They don't have to be visible but they do have to be instantiated for all types using them.
@PeterWood +1 ... arguably overkill for this question though.
This whole question is overkill as many have asked it before (c:

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