“未定义符号"简单模板类的链接器错误

quot;Undefined symbolsquot; linker error with simple template class(“未定义符号简单模板类的链接器错误)

问题描述

离开 C++ 几年了，我从以下代码中收到链接器错误:

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

基因.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

基因.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;
}

如果对任何人都很重要，请使用 Code::Blocks 和 GCC.此外，为了好玩和练习，显然将一些 GA 内容移植到 C++.

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

必须在实例化给定模板类之前包含模板定义(代码中的 cpp 文件)，因此您必须在标头，或在使用类之前#include cpp 文件(或者如果数量有限，则进行显式实例化).

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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