个人中心
gpt4 book ai didi

c++ - 从 vector 中的父基转换的模板化子 T 生成的虚假字符

转载 作者：太空宇宙 更新时间：2023-11-04 12:32:12 25 4
gpt4 key购买 nike

<分区>

我正在使用一种将基类分配给模板化类的模式，这样我就可以将不同的类型放入一个 vector 中，相对于 Attribute<String>和 Attribute<int> ，这样做的原因是我想要一个包含继承相同基础对象的不同对象的 vector 。

我遇到的生成虚假文本的问题与从 vector 中检索 Base 对象并转换回原始 Attribute 模板对象后生成的输出有关。

问题输出，使用内联注释显示输出与预期不同的地方:


        T (String)
        ID: Id-1
        Key: -�'��,�'�8���Id-1  // expected key1
        Value:                  // expected one

        T (String)
        ID: Id-2
        Key: -�'��,�'�8���Id-2  // expected key2
        Value:                  // expected two

        T (String)
        ID: Id-3
        Key: -�'��,�'�8���Id-3  // expected key3
        Value:                  // expected three

        T (int)
        ID: Id-4
        Key: -�'��,�'�8���Id-4  // expected key4
        Value: 0                // expected 4

        T (String)
        ID: Id-5
        Key: -�'�-�'�8���Id-5   // expected key5
        Value:                  // expected 5

        T (int)
        ID: Id-6
        Key: -�'�0-�'�8���Id-6  // expected key6
        Value: 0                // expected 6

这是可重现的示例，我添加了一个使用 c++ 编译器而不是 g++ 编译器的 Makefile，因为在 Mac 上(我正在这样做)C++17 尚未完全实现。

线束.cpp

#include <iostream>
#include "Attribute.h"
#include <vector>

using namespace std;
using String = std::string;

int main()
{

    // TEST THE Attribute CLASS BY ITSELF

    Attribute <String> att("testkey","testvalue", TypeRef::String, "testId");

    cout << "Key: "+att.getKey() << endl;;
    cout << "Value: "+att.getValue() << endl;
    cout << "Id: "+att.getId() << endl;
    cout << endl;

    /* Output:

        Key: testkey
        Value: testvalue
        Id: testId

    */

    // TEST SIX INSTANCES OF Attribute CLASS BEFORE ADDING TO vector

    std::vector<AttributeObject> vector; 

    Attribute<String> q("key1","one",TypeRef::String, "Id-1"); AttributeObject &qBase = q;
    cout << "T (String)" << endl;
    cout << "Id1: " << q.getId() << endl;    
    cout << "Key1: " << q.getKey() << endl;
    cout << "Value1: " << q.getValue() << endl;

    cout << endl;

    Attribute<String> w("key2","two",TypeRef::String, "Id-2"); AttributeObject &wBase = w; 
    cout << "T (String)" << endl;
    cout << "Id2: " << w.getId() << endl;    
    cout << "Key2: " << w.getKey() << endl;
    cout << "Value2: " << w.getValue() << endl;

    cout << endl;

    Attribute<String> e("key3","three",TypeRef::String, "Id-3"); AttributeObject &eBase = e;
    cout << "T (String)" << endl;
    cout << "Id3: " << e.getId() << endl;    
    cout << "Key3: " << e.getKey() << endl;
    cout << "Value3: " << e.getValue() << endl;

    cout << endl;

    Attribute<int> r("key4",4,TypeRef::Int, "Id-4"); AttributeObject &rBase = r; 
    cout << "T (int)" << endl;
    cout << "Id4: " << r.getId() << endl;    
    cout << "Key4: " << r.getKey() << endl;
    cout << "Value4: " << r.getValue() << endl;

    cout << endl;

    Attribute<int> t("key5",5,TypeRef::String, "Id-5"); AttributeObject &tBase = t; 
    cout << "T (int)" << endl;
    cout << "Id5: " << t.getId() << endl;    
    cout << "Key5: " << t.getKey() << endl;
    cout << "Value5: " << t.getValue() << endl;

    cout << endl;

    Attribute<int> y("key6",6,TypeRef::Int, "Id-6"); AttributeObject &yBase = y; 
    cout << "T (int)" << endl;
    cout << "Id6: " << y.getId() << endl;    
    cout << "Key6: " << y.getKey() << endl;
    cout << "Value6: " << y.getValue() << endl;

    cout << endl;

    cout << endl;

    /* Output:

        T (String)
        Id1: Id-1
        Key1: key1
        Value1: one

        T (String)
        Id2: Id-2
        Key2: key2
        Value2: two

        T (String)
        Id3: Id-3
        Key3: key3
        Value3: three

        T (int)
        Id4: Id-4
        Key4: key4
        Value4: 4

        T (int)
        Id5: Id-5
        Key5: key5
        Value5: 5

        T (int)
        Id6: Id-6
        Key6: key6
        Value6: 6

    */

    vector.push_back(qBase);
    vector.push_back(wBase);
    vector.push_back(eBase);
    vector.push_back(rBase);
    vector.push_back(tBase);
    vector.push_back(yBase);

    // TEST ALL Attribute CLASS INSTANCES AS EXTRACTED FROM A vector

    int x = 0;
    for (AttributeObject baseObject : vector) {

        TypeRef typeRef = baseObject.getTypeRef();
        if(typeRef == TypeRef::String)
        {
            cout << endl;
            cout << "T (String)" << endl;
            Attribute <String> *pChild =  (Attribute <String> *) &baseObject;
            cout << "ID: " << pChild->getId() << endl; 
            const String sKey = pChild->getKey();
            cout << "Key: " << sKey << endl;
            const String sValue = pChild->getValue();
            cout << "Value: " << sValue << endl;
        }
        else if(typeRef == TypeRef::Int)
        {
            cout << endl;
            cout << "T (int)" << endl;
            Attribute <int> *pChild =  (Attribute <int> *) &baseObject;
            cout << "ID: " << pChild->getId() << endl; 
            const String sKey = pChild->getKey();
            cout << "Key: " << sKey << endl;
            const int iValue = pChild->getValue();
            cout << "Value: " << (int)iValue << endl;

        }
        x++;
    }

    /* Output (with differing expected values added as inline comments)

        T (String)
        ID: Id-1
        Key: -�'��,�'�8���Id-1  // expected key1
        Value:                  // expected one

        T (String)
        ID: Id-2
        Key: -�'��,�'�8���Id-2  // expected key2
        Value:                  // expected two

        T (String)
        ID: Id-3
        Key: -�'��,�'�8���Id-3  // expected key3
        Value:                  // expected three

        T (int)
        ID: Id-4
        Key: -�'��,�'�8���Id-4  // expected key4
        Value: 0                // expected 4

        T (String)
        ID: Id-5
        Key: -�'�-�'�8���Id-5   // expected key5
        Value:                  // expected 5

        T (int)
        ID: Id-6
        Key: -�'�0-�'�8���Id-6  // expected key6
        Value: 0                // expected 6
    */

    return 0;
}

Attribute.cpp(这里只是为了 Makefile，因为如果您不使用 .cpp 文件，c++ 编译器会生成一个讨厌的警告):

#include "Attribute.h"

属性.h:

#include <iostream>
#include <string>
#include <type_traits>
#include <vector>

using String = std::string;

enum class TypeRef {   
    String,
    Int
};

class AttributeObject{
    public:
            AttributeObject() {}
            AttributeObject(TypeRef typeRef, String Id) : typeRef(typeRef), id(Id) {}

            TypeRef getTypeRef()
            {
                return this->typeRef;
            }

            String getId()
            {
                return this->id;
            }


    protected:
            TypeRef typeRef;
            String id;
};

template<class T>
class Attribute : public AttributeObject {
public:
    using value_type = T;

    Attribute(const String& Key, const T& Value, const TypeRef& TypeRef, const String& Id) : 
        AttributeObject(TypeRef, Id),
        key(Key),        
        value(Value)
        {}

    String const& getKey() const {
        return key;
    };
    T const& getValue() const {
        return value;
    }

    TypeRef const& getTypeRef() const {
        return typeRef;
    }

private:
    String key;
    T value;
};

生成文件:

CC=c++
FLAGS=-c -g -std=c++17

All: build

mkdirs:
    # In mkdirs:
    mkdir -p obj

build: clean mkdirs harness.o Attribute.o
    # In build:
    $(CC) obj/harness.o obj/Attribute.o -o harness
    ls

harness.o: harness.cpp
    # harness.o:
    $(CC) $(FLAGS) harness.cpp -o obj/harness.o
    ls obj

Attribute.o: Attribute.cpp
    $(CC) $(FLAGS) Attribute.cpp -o obj/Attribute.o
    ls obj

clean:
    # In clean:
    rm -rf obj
    ls

亲切的问候。

25 4 0
文章推荐： python - 使用 Python 在 Linux 终端中同时运行进程
文章推荐： java - 我的星号框程序无法正常工作
文章推荐： javascript - 找不到 null 的 innerHTML，css3 过渡翻转
文章推荐： java - 如何处理Spring Boot注释中的403禁止错误？
太空宇宙
个人简介

我是一名优秀的程序员,十分优秀！

滴滴打车优惠券免费领取
滴滴打车优惠券
全站热门文章
Copyright 2021 - 2024 cfsdn All Rights Reserved 蜀ICP备2022000587号
广告合作:1813099741@qq.com 6ren.com