Question

//this is my source file, .cpp
#include <iostream>
#include <string>
#include "kingdom.h"
namespace westeros{
    void display(Kingdom pKingdom[], int kingdomElement, string KingdomName){
        cout << " ---------------- " << endl;
        cout << " Searching for kingdom " << KingdomName << " in westeros " << endl;
        for(int i=0; i<kingdomElement; i++){
            if (pKingdom[i].m_name == KingdomName){
                cout << " --------------------- " << endl;
                cout << KingdomName << ", population " << pKingdom[i].m_population << endl;
                cout << " --------------------- " << endl;
            }

            else{
                cout << " --------------------- " << endl;
                cout << KingdomName << " is not part of Westeros. " << endl;
                cout << " --------------------- " << endl;
            }
        }
    }
}
//this is my main file
#include <iostream>
#include "kingdom.h"
#include <string>
using namespace std;
using namespace westeros;

int main(void){
    int count = 0;
    Kingdom* pKingdoms = nullptr;
    pKingdoms = new Kingdom[count];
    display(pKingdoms, count, "Mordor");
    display(pKingdoms, count, "The_Vale");
    delete[]pKingdoms;
    pKingdoms = nullptr;
    return 0;
}

//this is my header file
#ifndef KINGDOM_H_
#define KINGDOM_H_
using namespace std;
namespace westeros{
    class Kingdom{
    public:
        char m_name[32];
        int m_population;  
    };
    void display(Kingdom pKingdom[], int kingdomElement, string KingdomName);
}
#endif

现在打印

Mordor不属于维斯特洛魔多不属于维斯特洛魔多不属于维斯特洛魔多不属于维斯特洛 Mordor不属于Westeros

The_Vale不属于维斯特洛 The_Vale，人口234567 The_Vale不是维斯特洛的一部分 The_Vale不是维斯特洛的一部分 The_Vale不是Westeros的一部分

Answer 1

int count = 0;
Kingdom* pKingdoms = nullptr;
pKingdoms = new Kingdom[count];

这会创建一个包含count = 0元素的数组。任何进一步的访问都将超出范围。

我建议你使用std::vector：

std::vector<Kingdom> kingdoms(/*(good) count*/);

std::string的{{1}}类型。

当我看到这条线时：

char m_name[32];

我希望循环跟随，而不是cout << " Searching for kingdom " << KingdomName << " in westeros " << endl;。还有一些代码首先用一些名称填充数组。

if =＆gt;之后if版：您应该打印

KingdomName不属于Westeros。

后循环不在内部，且仅在未找到for的情况下。

Answer 2

也许您忘了将The_Vale添加到pKingdoms数组。

所以，这样的事情会让你明白你做错了什么：

在主文件中你可以改进它，如下所示，所有其他文件都可以;）

    //this is my main file
  #include <iostream>
  #include "kingdom.h"
  #include <string.h>
  using namespace std;
  using namespace westeros;

  int main(void){
      int count = 0;

      // Kingdom* pKingdoms = nullptr;
      // pKingdoms = new Kingdom[count];
      Kingdom* pKingdoms = new Kingdom[count];   // Might be a better choice,
                                          // as it reduces code.

      display(pKingdoms, count, "Mordor");      // pKingdoms doesn't have Mordor
      display(pKingdoms, count, "The_Vale");    // pKingdoms doesn't have The_vale

      // Here I add the 'The_Vale to the array 
      strcpy(pKingdoms[0].m_name, "The_Vale");
      pKingdoms[0].m_population = 1000;

      display(pKingdoms, count, "The_Vale");    // pKingdoms have The_vale

      delete[]pKingdoms;
      pKingdoms = nullptr;
      return 0;
  }

在编辑之后，也许source.cpp中的这样的东西会有所帮助。

//this is my source file, .cpp
#include <iostream>
#include <string>
#include "kingdom.h"
namespace westeros{
    void display(Kingdom pKingdom[], int kingdomElement, string KingdomName){
      int flag = -1;
        cout << " ---------------- " << endl;
        cout << " Searching for kingdom " << KingdomName << " in westeros " << endl;

        for(int i=0; i<kingdomElement; i++)
            if (pKingdom[i].m_name == KingdomName)
                flag = i;

        if (flag != -1)
        {
            cout << " --------------------- " << endl;
            cout << KingdomName << ", population " << pKingdom[flag].m_population << endl;
            cout << " --------------------- " << endl;
        }

        else{
              cout << " --------------------- " << endl;
              cout << KingdomName << " is not part of Westeros. " << endl;
              cout << " --------------------- " << endl;
        }
    }
}

如果语句不起作用，则跳过其他部分

2 个答案: