C / C++ / MFC

fstream in("test.txt",ios::in | ios::out);
if(!in)
    cout<<"error...";
else
{
    char ch;
    in.seekg(0,ios::end);
    int end=in.tellg();//get the length

    in.seekg(0);//get back to the start
    for(int i=0;i<end;i++)
    {
       //in.seekg(in.tellg());//if i uncomment this the code will work
       if(!in.get(ch).fail())//read a character
       {
           in.seekp(static_cast<int>(in.tellg())-1);//move the pointer back to the previously read position,so i could write on it
           if(in.put(ch).fail())//write back,this also move position to the next character to be read/write
               break;//break on error
       }
    }
}

#include <stdlib.h>
#define __CL_ENABLE_EXCEPTIONS
#pragma warning(disable:4996)
#include <CL/cl.hpp>
#include <fstream>
#include <iostream>
#include <time.h>
#include <cmath>

#define LOCAL_SIZE 512
#define WIDTH_A (4096*2)
#define HEIGHT_A (4096*2)

float *matrix_A;
float *vector_B;
float *result_vector;
float *result_vector_host;


#define MAX_SOURCE_SIZE (0x100000)	

int main()
{
	cl_platform_id platform_id = NULL;
	cl_device_id device_id = NULL;
	cl_context context = NULL;
	cl_command_queue command_queue = NULL;
	cl_mem Amobj = NULL;
	cl_mem Bmobj = NULL;
	cl_mem Cmobj = NULL;
	cl_program program = NULL;
	cl_kernel kernel = NULL;
	cl_uint ret_num_devices;
	cl_uint ret_num_platforms;
	cl_int ret;

	int i, j;

	/* Get Platform/Device Information*/
	ret = clGetPlatformIDs(1, &platform_id, &ret_num_platforms);
	ret = clGetDeviceIDs(platform_id, CL_DEVICE_TYPE_DEFAULT, 1, &device_id, &ret_num_devices);

	/* Create OpenCL Context */
	context = clCreateContext(NULL, 1, &device_id, NULL, NULL, &ret);


	char buffer[10240];
	cl_uint buf_uint;
	cl_ulong buf_ulong;
	printf("Num of devices=%i", ret_num_devices);
	for (i = 0; i < ret_num_devices; i++)
	{
		printf("  -- %d --\n", i);
		clGetDeviceInfo(device_id, CL_DEVICE_NAME, sizeof(buffer), buffer, NULL);
		printf("  DEVICE_NAME = %s\n", buffer);
		clGetDeviceInfo(device_id, CL_DEVICE_VENDOR, sizeof(buffer), buffer, NULL);
		printf("  DEVICE_VENDOR = %s\n", buffer);
		clGetDeviceInfo(device_id, CL_DEVICE_VERSION, sizeof(buffer), buffer, NULL);
		printf("  DEVICE_VERSION = %s\n", buffer);
		clGetDeviceInfo(device_id, CL_DRIVER_VERSION, sizeof(buffer), buffer, NULL);
		printf("  DRIVER_VERSION = %s\n", buffer);
		clGetDeviceInfo(device_id, CL_DEVICE_MAX_COMPUTE_UNITS, sizeof(buf_uint), &buf_uint, NULL);
		printf("  DEVICE_MAX_COMPUTE_UNITS = %u\n", (unsigned int)buf_uint);
		clGetDeviceInfo(device_id, CL_DEVICE_MAX_CLOCK_FREQUENCY, sizeof(buf_uint), &buf_uint, NULL);
		printf("  DEVICE_MAX_CLOCK_FREQUENCY = %u\n", (unsigned int)buf_uint);
		clGetDeviceInfo(device_id, CL_DEVICE_GLOBAL_MEM_SIZE, sizeof(buf_ulong), &buf_ulong, NULL);
		printf("  DEVICE_GLOBAL_MEM_SIZE = %llu\n", (unsigned long long)buf_ulong);
	}
}

l created an application with a button "LogOut", which l want, when the user clicks the LogOut button, the application starts afresh. Just like in a standard program(eg. MSWORD) where when "New" is clicked, a new workspace pops out. So l need help in making my program to start afresh when LogOut button is clicked.

case IDC_LOGOUTBTN:
 SendMessage(hWnd,WM_CREATE, 0,(LPARAM)lpcs)//where lpcs is a pointer to CreateStruct structure.
break;

At some point in my program, l generate random numbers using srand((unsigned)time(&t)) and rand() functions when NEXT button is clicked. But l want to know if there is anyway to get the previous random number(s) when PREVIOUS button is clicked?