用于C ++代码的std :: out_of_range

Question

我在运行此代码时遇到错误。执行时会发出错误，如 -

  

在抛出'std :: out_of_range'的实例后终止调用   what（）：basic_string :: substr

关于我在这里做错了什么想法？

#include <string.h>
#include <cstring>
#include <string>
#include <iostream>
#include <fstream>
#include "fix_nvt.h"
#include "group.h"
#include "modify.h"
#include "error.h"

using namespace LAMMPS_NS;
using namespace FixConst;
using namespace std;

 std::ifstream inFile;

double x,y,z;
string str_val;

/* ---------------------------------------------------------------------- */

FixNVT::FixNVT(LAMMPS *lmp, int narg, char **arg) :
  FixNH(lmp, narg, arg)
{
  if (!tstat_flag)
    error->all(FLERR,"Temperature control must be used with fix nvt");
  if (pstat_flag)
    error->all(FLERR,"Pressure control can not be used with fix nvt");

  // create a new compute temp style
  // id = fix-ID + temp

  int n = strlen(id) + 6;
  id_temp = new char[n];
  strcpy(id_temp,id);
  strcat(id_temp,"_temp");

  char **newarg = new char*[3];
  newarg[0] = id_temp;
  newarg[1] = group->names[igroup];
  newarg[2] = (char *) "temp";

  modify->add_compute(3,newarg);
  delete [] newarg;
  tflag = 1;
  printf("syracuse rocks\n\n\n");
  inFile.open("matrix.txt", ios::in);
  while(getline(inFile,str_val));
    {
  x = atof(str_val.substr(1,4).c_str());
  y = atof(str_val.substr(17,4).c_str());
  z = atof(str_val.substr(33,4).c_str());
  printf ("x = %f, y =%f, z=%f\n",x,y,z);
 }
  inFile.close();



}