MPI result file all goes to .o file [file i/o error]

Question

Since my school's server can only be accessed with my school IP, sorry for no screenshots. I'll explain detailed.

Below is main file(Not important).

MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &size);
MPI_Comm_rank(MPI_COMM_WORLD, &myid);

/** distributing numbers to each node(e.g. distributing 1~100 numbers to 7 nodes: node 1 get 1, 8, 15, 22, ... node 2 get 2, 9, ...) **/    
qu = new mpi_que[size];
for (int i = 1; i <= size; i++) {
    qu[i-1].setId(i);
    qu[i-1].allocate(repeat_number, size - 1);
}

if (myid == MASTER_ID) // 0
    Master();
else
    Slave();

MPI_Finalize();

and this is Slave function.

void Slave() {
    //printf("I am Slave %d out of %d\n", myid, size - 1);

    Sand s(w, h);

    while (!qu[myid - 1].isFinished()) {
        int id_now = qu[myid - 1].current_id();
        int seed = time(NULL) + id_now;

        /** Do some Jobs**/
        string filename = "./data/avalanche" + ToString(w) + "x" + ToString(h) + "_drop" + ToString(count) + "_id" + ToString(id_now) + ".binary";
        writemod(aftershock, aftershock_length, filename);

        qu[myid - 1].finishOneJob();
    }
}

qu is global pointer which I made. I don't think error occurs here. what qu does is changing id_now's value every loop, and so filename changes each loop.

Below is writemod function.

#define WRITE_VAR(_stream, v)   (_stream.write( (char *)(&(v)), sizeof(v)   ))

void writemod(afterBig a[], int len, string path) {

    ofstream outFile((path).c_str(), ios::binary);

    WRITE_VAR(outFile, len);
    for (int i = 0; i < len; i++) {
        WRITE_VAR(outFile, a[i].big_size);
        WRITE_VAR(outFile, a[i].after_size);
    }

    outFile.close();
}

Anyway, what happens when I run this file is that

if I run this file, all output file data seems to go to [jobname].o[jobid] file(default output text file). It's 8.7Gb so I can't even open it with emacs to see what have happened.