shel2dos.c

C语言库函数的源代码,是C语言学习参考的好文档。

/* +++Date last modified: 05-Jul-1997 */

/*
**  SHEL2DOS.C - Shell to DOS from a running program
**
**  Original Copyright 1989-1991 by Bob Stout as part of
**  the MicroFirm Function Library (MFL)
**
**  The user is granted a free limited license to use this source file
**  to create royalty-free programs, subject to the terms of the
**  license restrictions specified in the LICENSE.MFL file.
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <process.h>
#include "snpdosys.h"

int shell_to_DOS(void)
{
      char *comspec, prompt[256], *oldprompt;
      int retval;

      comspec = getenv("COMSPEC");
      if(comspec == NULL)
            comspec = "COMMAND.COM";     /* Better than nothing... */

      sprintf(prompt, "PROMPT=[Type EXIT to return to program]\r\n%s",
            oldprompt = getenv("PROMPT"));
      putenv(prompt); 

      retval = spawnlp(0, comspec, comspec, NULL);

      sprintf(prompt, "PROMPT=%s", oldprompt);
      putenv(prompt);

      return retval;
}

#ifdef TEST

#include <stdio.h>

main()
{
      int retval = shell_to_DOS();

      printf("shell_to_DOS() returned %d\n", retval);

      retval = shell_to_DOS();
      printf("shell_to_DOS() returned %d\n", retval);
      return 0;
}

#endif /* TEST */