二进制分段错误 11

Question

I'm trying to write to a binary file, such that I have time, id1, id2, and two garbage bytes (0) per line. When I do this without the garbage bytes, it works, but once I add the garbage bytes, I get "segmentation fault 11" as an error. I'm sure the CastorArray2 is written correctly (checked before this block of code).

Here is my code:

    struct Packet
    {
    //int64_t Time;                                                                                                                                                                                                                              
    uint32_t Time;
    uint32_t Crystal_ID1;``
    uint32_t Crystal_ID2;
    int Garbage1;
    int Garbage2;
    };
    printf("working before opening file");
    ofstream myfile;
    myfile.open("/Users/Desktop/Archive/WorkNEW.dat", ios::binary | 
    ios::out);
    if (myfile.is_open()) {
        printf("file open");
     // cout<< "cannot open file!" << endl;                                                                                                                                                                                                 
     // return 1;                                                                                                                                                                                                                           
    }
    Packet Event[495842];
    for (int n=0; n<495842; n++)
    {
        Event[n].Time=1.0;
        //       Event[n].Time=CastorArray2[n][3];                                                                                                                                                                                          
        Event[n].Crystal_ID1=CastorArray2[n][1];
        Event[n].Crystal_ID2=CastorArray2[n][2];
        Event[n].Garbage1=0;
        Event[n].Garbage2=0;
    }
    if (myfile.is_open()) {
        printf("Works");

     //   cout<<"file opened successfully"<<endl;                                                                                                                                                                                           
     //   return 1;                                                                                                                                                                                                                         
        for (int m=0;m<495842;m++)
        {
                                                                                                                                                   
          myfile.write((char*) &Event[m], sizeof(Packet));
        }
        myfile.close();
    }
    else {
        printf("notworking");
     //cout<< "unable to open file"<<endl;                                                                                                                                                                                                  
        return 1;
    }
    
   //}                                                                                                                                                                                                                                      
    
    return 0;

Answer 1

If I understand your code correctly you are allocating way too much on your stack frame.

Packet Event[495842];

495842 instances of Packet sums to about 20 MB of stack memory.

A simple solution would be

std::vector<Packet> event(495842);

For the "new to c++ comment", std::vector allows you to use [index] syntax in the same fashion you use it on arrays.

@user451301 makes a good point. The stack is created when the program is started. It doesn't change afterwards. It is meant to hold the state of function calls including variables and arrays. In this case a function call exceeds the available stack space and forcibly terminates the program.