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C/C++ Users Group Library 1996 July
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C-C++ Users Group Library July 1996.iso
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v_01_02
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1n02061a
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1990-07-08
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149 lines
/*
** Listing 7 - PushDir() and PopDir()
*/
#include <dos.h>
#include <stdlib.h>
#include <string.h>
#define DIR_STACK_SIZE 8
#define MAX_FLEN 67
typedef enum {ERROR = -1, FALSE, TRUE} LOGICAL;
int chdrv(int);
static int PushDir_stack_ptr;
static char PushDir_stack[DIR_STACK_SIZE][MAX_FLEN];
/*********************************************************************/
/* */
/* PushDir() */
/* */
/* Like chdir(), except a drive may be specified and the old */
/* directory is saved. */
/* */
/* Arguments: 1 - newdir, the buffer containing the new directory */
/* name */
/* */
/* Returns: -1 - stack overflow */
/* 0 - error */
/* 1 - success, still on same drive */
/* 2 - success, changed drive */
/* */
/* Side effects: Converts name in newdir to upper case and prepends */
/* a drive letter. */
/* */
/* CAUTION: Since a drive will be prepended to newdir, it's buffer */
/* should be at at least MAX_FLEN long. */
/* */
/*********************************************************************/
int PushDir(char *newdir)
{
char pname[MAX_FLEN];
char drive[3];
char *target = &pname[2];
int i, new_drv = 0, ercode = 0;
static int init = 0;
if (!init)
PushDir_stack_ptr = init = -1;
if (DIR_STACK_SIZE <= ++PushDir_stack_ptr)
{
ercode = -1;
goto ErrEx;
}
getcwd(PushDir_stack[PushDir_stack_ptr], MAX_FLEN);
strupr(PushDir_stack[PushDir_stack_ptr]);
strncpy(drive, PushDir_stack[PushDir_stack_ptr], 2);
drive[2] = '\0';
if (':' == newdir[1])
{ /* If a drive is specified */
strupr(newdir);
strcpy(pname, newdir);
if (strchr(target, ':')) /* if filename is illegal */
goto ErrEx;
if (*drive != *newdir)
{
if (ERROR == chdrv(newdir[0]))
{ /* If the drive is invalid */
goto ErrEx;
}
else new_drv = 1;
}
}
else
{ /* If a drive isn't specified */
if (!strchr(strupr(newdir), ':'))
{ /* If legal filename */
strcpy(pname, drive);
strcat(pname, newdir);
strcpy(newdir, pname);
}
else
{ /* If filename is illegal */
goto ErrEx;
}
}
if (*target)
{
if (chdir(target))
{
if (1 == new_drv) /* We already changed
drives */
chdrv(*drive); /* Go home before exit */
goto ErrEx;
}
}
return (new_drv + 1);
ErrEx: --PushDir_stack_ptr;
return (ercode);
}
/*********************************************************************/
/* */
/* PopDir() */
/* */
/* Like chdir(), except goes to the drive/directory specified on */
/* the top of the PushDir stack. */
/* */
/* Arguments: none */
/* */
/* Returns: -1 - stack empty */
/* 0 - error - stack pointer unchanged */
/* 1 - success, still on same drive */
/* 2 - success, changed drive */
/* */
/* Side effects: none */
/* */
/* CAUTION: chdir() or chdrv() should not be called between PushDir-*/
/* PopDir calls. */
/* */
/*********************************************************************/
int PopDir(void)
{
char I_am_here[MAX_FLEN], target_drv, *target;
int new_drv = 0;
if (0 > PushDir_stack_ptr)
return -1;
getcwd(I_am_here, MAX_FLEN);
target = &PushDir_stack[PushDir_stack_ptr][2];
target_drv = PushDir_stack[PushDir_stack_ptr][0];
if (I_am_here[0] != target_drv)
{
if (ERROR == chdrv(target_drv))
return 0;
new_drv = 1;
}
if (!chdir(target))
{
--PushDir_stack_ptr;
return (1 + new_drv);
}
else return 0;
}