xxxx没有命名c++类型

xxxx does not name a type C++

本文关键字：c++ 类型 xxxx      更新时间：2023-10-16

我是C/c++的新手，正在努力提高编码技能。我正在写一个最小的代码来计算我在大学学习中使用的公式。这段代码由许多类组成。当我试图构建它时，在类的标题中出现了错误。下面是我的代码:

materials.hpp 

#ifndef MATERIALS_HPP
#define MATERIALS_HPP
#include <cmath>
#include <iostream>
using namespace std;
class materials{
public: 
double MassNumber, AtomNumber, Density, I, C, a, m, X1, X0, X, delta; 
    materials();
    materials(double, double, double, double, double, double, double, double, double);
     ~materials();
};
materials Magnesium;
materials Cupper;
materials Alluminium;
materials Plumbo;
materials Water;
#endif // MATERIALS_HPP

这是来源;

materials.cpp 

#include "materials.hpp"
#include <cmath>
#include <iostream>
using namespace std;
materials::materials()
{
    MassNumber = AtomNumber = Density = I = a = m = C = X1 = X0 = X = delta = 0.0;
}
materials::materials(double a1, double a2, double a3, double a4, double a5, double a6,double a7, double a8, double a9)
{
    MassNumber = a1;
    AtomNumber = a2;
    Density = a3;
    I = a4;
    C = a5;
    a = a6;
    m = a7;
    X1 = a8;
    X0 = a9;
}
Magnesium.materials(23.0, 12.0, 1.738, 156.0, -4.53, 0.0816, 3.62, 3.07, 0.1499);
Cupper.materials(63.0, 29.0, 8.96, 322.0, -4.42, 0.1434, 2.90, 3.28, 0.0254);
Alluminium.materials(26.0, 13.0, 2.70, 166.0, -4.24, 0.0802, 3.63, 3.01, 0.1708);
Plumbo.materials(207.0, 82.0, 11.34, 823.0, -6.20, 0.0936, 3.16, 3.81, 0.3776);
Water.materials(18.0, 10.0, 1.0, 75.0, -3.50, 0.0911, 3.48, 2.80, 0.2400);

和我得到的错误;

materials.cpp:64:1: error: 'Magnesium' does not name a type
 Magnesium.materials(23.0, 12.0, 1.738, 156.0, -4.53, 0.0816, 3.62, 3.07, 0.1499
);
 ^
materials.cpp:66:1: error: 'Cupper' does not name a type
Cupper.materials(63.0, 29.0, 8.96, 322.0, -4.42, 0.1434, 2.90, 3.28, 0.0254);
^
materials.cpp:68:1: error: 'Alluminium' does not name a type
Alluminium.materials(26.0, 13.0, 2.70, 166.0, -4.24, 0.0802, 3.63, 3.01, 0.1708
);
^
materials.cpp:70:1: error: 'Plumbo' does not name a type
Plumbo.materials(207.0, 82.0, 11.34, 823.0, -6.20, 0.0936, 3.16, 3.81, 0.3776);
^
materials.cpp:72:1: error: 'Water' does not name a type
Water.materials(18.0, 10.0, 1.0, 75.0, -3.50, 0.0911, 3.48, 2.80, 0.2400);
^
make: *** [materials.o] Error 1

我在Linux上的GCC 4.9.0和Windows上的GCC 4.8.1的MinGW上尝试它。我读过其他关于它的文章，但我没能做到。为什么会出现这些错误?

你应该去找一本很好的介绍c++中类是如何工作的书。

问题是，你试图做某种奇怪的两部分结构，首先声明 
materials Magnesium;

然后尝试显式调用

Magnesium.materials(23.0, 12.0, 1.738, 156.0, -4.53, 0.0816, 3.62, 3.07, 0.1499);

但是构造函数在c++中不这样工作!

你应该这样做:

materials Magnesium(23.0, 12.0, 1.738, 156.0, -4.53, 0.0816, 3.62, 3.07, 0.1499);

这里不是解释类构造细节的地方，但我可以肯定地说，您应该对此做更多的研究。

如果您希望这些全局变量可以在其他源文件中访问:

在头文件中修改为: 

extern materials Magnesium;
extern materials Cupper;
extern materials Alluminium;
extern materials Plumbo;
extern materials Water;

在源文件中修改为:

materials Magnesium(23.0, 12.0, 1.738, 156.0, -4.53, 0.0816, 3.62, 3.07, 0.1499);
materials Cupper(63.0, 29.0, 8.96, 322.0, -4.42, 0.1434, 2.90, 3.28, 0.0254);
materials Alluminium(26.0, 13.0, 2.70, 166.0, -4.24, 0.0802, 3.63, 3.01, 0.1708);
materials Plumbo(207.0, 82.0, 11.34, 823.0, -6.20, 0.0936, 3.16, 3.81, 0.3776);
materials Water(18.0, 10.0, 1.0, 75.0, -3.50, 0.0911, 3.48, 2.80, 0.2400);

如果您不希望在其他源文件中访问这些全局变量:

从头文件中删除:

materials Magnesium;
materials Cupper;
materials Alluminium;
materials Plumbo;
materials Water;

在源文件中修改为:

static materials Magnesium(23.0, 12.0, 1.738, 156.0, -4.53, 0.0816, 3.62, 3.07, 0.1499);
static materials Cupper(63.0, 29.0, 8.96, 322.0, -4.42, 0.1434, 2.90, 3.28, 0.0254);
static materials Alluminium(26.0, 13.0, 2.70, 166.0, -4.24, 0.0802, 3.63, 3.01, 0.1708);
static materials Plumbo(207.0, 82.0, 11.34, 823.0, -6.20, 0.0936, 3.16, 3.81, 0.3776);
static materials Water(18.0, 10.0, 1.0, 75.0, -3.50, 0.0911, 3.48, 2.80, 0.2400);
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