rereading my file after extracting characters from it

Question

I know this is a widely asked question and there are answers even on this website, unfortunately, none of the answers helped me with my problem which is the following: i open a file and loop over its characters to see how many rows i will need to initialize my dynamic array, then i have another loop to reread the file found out how many columns i have (i know this inst so efficient), then i will input these chars to my 2d dynamic array. We can see here i reread the file several times. I have tried commands like seekg(),rewind(), closing the file and re-opening it none have worked, here is my code : (we have been giving a hint that each row ends with value 0, that should not be counted.)Any help is much appreciated.

//------------- include section -------------
  #include <iostream>
  #include <iomanip>
  #include <cstdlib>
  #include <new>
  #include <fstream>
  #include <cstring>
  #include <cctype>
//------------- using section -------------
 using std::cin;
 using std::cout;
 using std::cerr;
 using std::endl;
 using std::ifstream;
 using std::ofstream;
 using std::setw;
//------------- const section -------------
const int END_OF_LINE=-1;
const int LEN=100;
//------------- prototypes section -------------
void open_files(ifstream& if1, ifstream& if2);
void convert_to_matrix (ifstream &inp,int*matrix[],int num_of_rows);
void add_2_matrixes (int*matrix[],int* matrix2[],int num_of_rows,int 
num_of_rows2);
int get_length(ifstream & inp,int &length);
int get_rows(ifstream &inp, int &counter);
//------------- main -------------
 int main(int argc, char *argv[])
 {
   ifstream inp;
   ifstream inp2;
   open_files(inp,inp2);

    int num_of_rows=0,counter=0;
     num_of_rows=get_rows(inp,counter);
    int* matrix[num_of_rows];
    //fill rows and cols dynamically
    convert_to_matrix(inp,matrix,num_of_rows);
    int num_of_rows2=0;
    counter=0;
    num_of_rows2=get_rows(inp2,counter);
    //another matrix
    int* matrix1[num_of_rows2];
    //fill rows and cols dynamically
    convert_to_matrix(inp2,matrix1,num_of_rows2);
    add_2_matrixes(matrix,matrix1,num_of_rows,num_of_rows2);

    return EXIT_SUCCESS;

 }
//-----------------------------
void open_files(ifstream& inp, ifstream& inp2){

    char* st_file;
    char* nd_file;
    st_file=new(std::nothrow) char [LEN];
    nd_file=new(std::nothrow) char [LEN];
    //gets the first file name
    cin >> setw(LEN) >> st_file;

    inp.open(st_file);
    //gets the second file name
    cin >> setw(LEN) >> nd_file;

    inp2.open(nd_file);

    // if the opening command failed
    if ((!(inp.is_open())) || (!(inp2.is_open()))) {

        exit(EXIT_FAILURE);

    }
  }
 //------------------------------------------------
int get_rows(ifstream &inp, int &counter){
  int columns=0;
 while(!inp.eof())
 {
    counter++;
    inp>>columns;
    while (columns!=0)
    {
        inp>>columns;
    }

  }
   //!!!! (problem)
 inp.seekg(0,std::ios::beg);
 return counter;
 }
 //---------------------------------------------
  void convert_to_matrix (ifstream &inp,int* matrix[],int num_of_rows){
   //numbers is how many cols
   int length=0;
   //value of each col
   int number;

   for (int row=0;row<num_of_rows;row++){
      //open an array
      get_length(inp,length);
      matrix[row]=new(std::nothrow) int [length+1];
      //if null we failed
       if (matrix[row]==NULL)
       {
        cerr<<"Cannot allocate memory /n";
        exit(EXIT_FAILURE);
     }
     //else start filling in values
     for (number=0;matrix[row][number]!=0;number++)
     {
        inp>>matrix[row][number];
     }
     //at end of filling values last number is -1
     //to help us know when to stop
     matrix[row][number]=END_OF_LINE;
    }
}
//------------------------------------------------------
int get_length(ifstream &inp,int &length){
  int columns=0;
   inp>>columns;
   length++;
   while(columns!=0)
   {
    inp>>columns;
    length++;
   }
     //!!!!!(problem)
     inp.seekg(0,std::ios::beg);
     return length;
   }