“未定义符号”链接器错误与简单模板类 [英] "Undefined symbols" linker error with simple template class

问题描述

已离开C ++几年，并从以下代码得到链接器错误：

Been away from C++ for a few years and am getting a linker error from the following code:

Gene.h

#ifndef GENE_H_INCLUDED
#define GENE_H_INCLUDED

template <typename T>
class Gene {
    public:
    T getValue();
    void setValue(T value);
    void setRange(T min, T max);

    private:
    T value;
    T minValue;
    T maxValue;
};

#endif // GENE_H_INCLUDED

Gene.cpp

#include "Gene.h"

template <typename T>
T Gene<T>::getValue() {
    return this->value;
}

template <typename T>
void Gene<T>::setValue(T value) {
    if(value >= this->minValue && value <= this->minValue) {
        this->value = value;
    }
}

template <typename T>
void Gene<T>::setRange(T min, T max) {
    this->minValue = min;
    this->maxValue = max;
}

如果对任何人都重要，使用Code :: Blocks和GCC。此外，显然将一些GA的东西移植到C ++以便有趣和练习。

Using Code::Blocks and GCC if it matters to anyone. Also, clearly porting some GA stuff to C++ for fun and practice.

推荐答案

模板定义（代码中的cpp文件）必须在实例化给定模板类之前包含，因此您必须在头中包含函数定义，或在使用类之前#include cpp文件（如果数量有限，请执行显式实例化）。

The template definition (the cpp file in your code) has to be included prior to instantiating a given template class, so you either have to include function definitions in the header, or #include the cpp file prior to using the class (or do explicit instantiations if you have a limited number of them).

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