c++ - 处理指针 c++ 的段错误(这次有更多代码)

Question

我希望有人能帮助我解决我遇到的段错误，这次我发布了更多代码，希望每个人都能看到我正在尝试做什么。我确信这与我如何指向所有内容有关，因为这是我遇到麻烦的部分。这是.h

  using namespace std;
  // Data

  struct question{
  string programNum;
  string programDesc;
  string programPoints;
  string programInput;
  char* programQuestion;
  };

  void setQuestionFileName(question* q, char* fileName);
  void display(question* q);
  void display(question* q);

这是.cpp

using namespace std;


void setQuestionFileName(question* q, char* fileName){
    strcpy(q->programQuestion, fileName);
}

void display(question* q){

       cout << "Description           =  "   << q->programDesc     << endl;
       cout << "Number of Points      =  "   << q->programPoints   << endl;
       cout << "Name of Question File =  "   << q->programQuestion << endl;

}

// Not used or tested yet
int myCompare (const void * a, const void * b ) {
           const char *pa = *(const char**)a;
           const char *pb = *(const char**)b;

           return strcmp(pa,pb);
 }

和 main.cpp:

 using namespace std;

 int main(int argc, char* argv[]){                                                              //or char** argv
 question* questions[argc-1];                                                           //Array of questions to be filled by loop.
 int sizeOfQuestions = argc;                                                                    //number of questions passed in at run time
 int numLines = 0;                                                                          //number of lines in file
 for(int i=0;i<argc;i++){                                                                   //Test loop to make sure the command line file names are read in
          std::cout << argv[i] << " says hello" << std::endl;
 }
 for(int count=0;count<sizeOfQuestions-1;count++){                                          //This loop places the information from the files into structs
      //char fileName = argv[count+1];
      char* fileName = argv[count+1];
      cout << "Problem number:  " << count+1 << "\t Working with file " << fileName << endl;
      std::fstream questionFile (fileName, std::fstream::in);                                    //Open the file
      if(questionFile.good()){
            cout << "File Opened" << endl;
            setQuestionFileName(questions[count],fileName);
            cout << questions[count]->programQuestion << endl;
            getline(questionFile,questions[count]->programNum);
            getline(questionFile,questions[count]->programDesc);
            getline(questionFile,questions[count]->programPoints);
            getline(questionFile,questions[count]->programInput);
            display(questions[count]);
            questionFile.close();
       }else{
            cout << "Could not open file!!!" << endl;
       }

  }

  return 0;

  }

最后，输出:

     $ ./a.exe q1.txt q2.txt
     ./a says hello
     q1.txt says hello
     q2.txt says hello
     Problem number:  1       Working with file q1.txt
     File Opened
     Segmentation fault (core dumped)

Answer 1

因此，根据对您问题的评论，我建议了解调试器或习惯插入跟踪语句(例如 cout << "got here."; function(); cout << "got here以及!”；等)。

在这种情况下，看起来 question* questions[argc-1] 会咬你一口。它只是创建指向 question 的指针数组，而不是 question 的数组。

您可以按需分配这些(不要忘记事后清理)或使用一些可以更干净地管理生命周期的东西(查看 std::vector 以获得具有其他一些有用特征的基本数组替换).

开始分配结构后，您会注意到您还没有在结构中分配 programQuestion。可能是时候考虑将其作为一个类，或者看看 std::string 的工作方式了。您可以很容易地从 C 字符串(指向 char 的指针)进行初始化。请参阅:Converting a C-style string to a C++ std::string