directory file openong

hi!
1)my program ask my to open a file which is in a directory named DIR.how can i do this(i want to enter only the file name,without the complete path)?
2)how can i display time and date who change every second, and make delays lower than 1ms?

Use a FILE type.

Code:

#include <stdio.h>

int main (int argc, char *argv[])
{
   FILE *fp;

   if ( (fp = open("filename", r)) != NULL)
   {
       printf("error opening file.\n");
   }

   /* now do things with the file */

There is a good article that deals with "working with files in *nix" on this website. Look at the tutorials section. The tutorials mostly cover both Win/*nix

1) The simplest way would be to concatenate the string entered with a previously saved directory string:

Code:

#include <stdio.h>
#include <string.h>

FILE *
open_file_in(
  const char *path,
  const char *filename,
  const char *mode
  )
{
  char buf[BUFSIZ];

  strcpy(buf, path);
  strcat(buf, filename);

  return fopen(buf, mode);
}

int
main(void)
{
  FILE *in = open_file_in("C:\\", "test.txt", "r");
  char ch;

  if (!in) {
    perror(NULL);
  }
  while ((ch = getc(in)) != EOF) {
    putc(ch, stdout);
  }
  fclose(in);

  return 0;
}

2) Why do you need delays less than 1ms when the time only changes each second? Displaying the date and time is simple if you do a search on this forum. In fact, I believe the FAQ board has one potential answer to that question. High resolution delays are harder, and the solution depends on your operating system.

One of simpliest way is make delays on nanoseconds... ( *nix )

Code:

   ...
   usleep ( n ); 
   ...

people, look what i asked for:

#include <stdio.h>
#include <string.h>

void main(void){

FILE *fp;
char buf[40],filename[13];
strcpy(buf,"DIRNAME/");
clrscr();
printf("enter the file name:\n");
gets(filename);
strcat(buf,filename);

fp=fopen(buf,"rb");
if(fp==NULL){
printf(" file can't be opened");
exit(1);
}
......
main programme
......
fclose(fp);
exit(0);
}
it really works!
was that so complicated?
prelude, thanks for the idea!