[Libusb-win32-devel] runtime error as memory could not be read when using libusb..win32

[usha <sen...@gm...>]

i've written pgm in vc++,windows 2000...

my pgm code is
#include <stdio.h>
#include <string.h>
#include <usb.h>

void readwrite();
struct usb_endpoint_descriptor *endpoint;

int verbose = 0;
usb_dev_handle *udev;
char buf[40]="MEASUrement:IMMed:TYpe PK2PK?";
char buf1[25];
int size,i;

void print_endpoint(struct usb_endpoint_descriptor *endpoint)
{
  printf("bEndpointAddress: %02xh\n", endpoint->bEndpointAddress);
  printf("bmAttributes:     %02xh\n", endpoint->bmAttributes);
  printf("wMaxPacketSize:   %d\n", endpoint->wMaxPacketSize);
  printf("bInterval:        %d\n", endpoint->bInterval);
  printf("bRefresh:         %d\n", endpoint->bRefresh);
  printf("bSynchAddress:    %d\n", endpoint->bSynchAddress);
}

void print_altsetting(struct usb_interface_descriptor *interface)
{


  printf("bInterfaceNumber:   %d\n", interface->bInterfaceNumber);
  printf("bAlternateSetting:  %d\n", interface->bAlternateSetting);
  printf("bNumEndpoints:      %d\n", interface->bNumEndpoints);
  printf("bInterfaceClass:    %d\n", interface->bInterfaceClass);
  printf("bInterfaceSubClass: %d\n", interface->bInterfaceSubClass);
  printf("bInterfaceProtocol: %d\n", interface->bInterfaceProtocol);
  printf("iInterface:         %d\n", interface->iInterface);

  for (i = 0; i < interface->bNumEndpoints; i++)
  print_endpoint(&interface->endpoint[i]);
}

void print_interface(struct usb_interface *interface)
{
    for (i = 0; i < interface->num_altsetting; i++)
    print_altsetting(&interface->altsetting[i]);
}

void print_configuration(struct usb_config_descriptor *config)
{
  printf("wTotalLength:         %d\n", config->wTotalLength);
  printf("bNumInterfaces:       %d\n", config->bNumInterfaces);
  printf("bConfigurationValue:  %d\n", config->bConfigurationValue);
  printf("iConfiguration:       %d\n", config->iConfiguration);
  printf("bmAttributes:         %02xh\n", config->bmAttributes);
  printf("MaxPower:             %d\n", config->MaxPower);

  for (i = 0; i < config->bNumInterfaces; i++)
  print_interface(&config->interface[i]);
}

int print_device(struct usb_device *dev, int level)
{
  //char description[256];
  //char string[256];
  //int ret;

if (!dev->config) 
{
	printf("  Couldn't retrieve descriptors\n");
	return 0;
	for (i = 0; i < dev->descriptor.bNumConfigurations; i++){
		print_configuration(&dev->config[i]);}
}
else 
{
	for (i = 0; i < dev->num_children; i++){
		print_device(dev->children[i], level + 1);}
}
return 0;
}

int main()//int argc, char *argv[])
{
  struct usb_bus *bus;
 // if (argc > 1 && !strcmp(argv[1], "-v"))
  verbose = 1;

  usb_init();
  usb_find_busses();
  usb_find_devices();

  for (bus = usb_get_busses(); bus; bus = bus->next) {
    if (bus->root_dev && !verbose)
      print_device(bus->root_dev, 0);
    else {
      struct usb_device *dev;
      for (dev = bus->devices; dev; dev = dev->next)
        print_device(dev, 0);
    }
  }
readwrite();
  return 0;
}
void readwrite()
{
size=strlen(buf);
usb_bulk_write(udev,endpoint->bEndpointAddress,buf,size,100);
usb_bulk_read(udev,endpoint->bEndpointAddress,buf1,size,100);

for(i=0;i<size;i++)
{
	printf("%d",buf1[i]);
}

}
i'm getting error as 
C:\WINNT\system32\ntdll.dll', no matching symbolic information found.
Loaded 'C:\WINNT\system32\KERNEL32.DLL', no matching symbolic information found.

please give me a solution...
thanks n advance...