C语言 如何使用 opendir() 获取目录名

Question

我想用函数opendir()通过命令行获取目录的名称，但我不知道如何...我已经实现了函数do_ls，我正在尝试通过命令行传递目录的名称作为参数。

#include    <stdio.h>
#include    <sys/types.h>
#include    <dirent.h>
#include    <sys/stat.h>
#include    <string.h>
void do_ls(char *);
void dostat(char *);
void show_file_info( char *, struct stat *);
void mode_to_letters( int , char [] );
char *uid_to_name( uid_t );
char *gid_to_name( gid_t );

int main(int ac, char *av[])
{
    if ( ac == 1 )
        do_ls( "." );
    else
        while ( --ac ){
            printf("%s:n", *++av );
            do_ls( *av );
        }
    return 0;
}

void do_ls( char argv[] )
/*
 *  list files in directory called dirname
 */
{
    DIR     *dir_ptr;       
    struct dirent   *direntp;       
    if ( ( dir_ptr = opendir( argv[0]) ) == NULL )
        fprintf(stderr,"ls2: cannot open %sn", argv[0]);
    else
    {
        while ( ( direntp = readdir( dir_ptr ) ) != NULL ) {
            if (strcmp(direntp->d_name,".")==0 ||
                strcmp(direntp->d_name,"..")==0) continue;
            dostat( direntp->d_name );
        }
        closedir(dir_ptr);
    }
}

void dostat( char *filename )
{
    struct stat info;
    if ( stat(filename, &info) == -1 )      /* cannot stat   */
        perror( filename );         /* say why   */
    else                    /* else show info    */
        show_file_info( filename, &info );
}

void show_file_info( char *filename, struct stat *info_p )
/*
 * display the info about 'filename'.  The info is stored in struct at *info_p
 */
{
    char    *uid_to_name(), *ctime(), *gid_to_name(), *filemode();
    void    mode_to_letters();
        char    modestr[11];
    mode_to_letters( info_p->st_mode, modestr );
    printf( "%s"    , modestr );
    printf( "%4d "  , (int) info_p->st_nlink);  
    printf( "%-8s " , uid_to_name(info_p->st_uid) );
    printf( "%-8s " , gid_to_name(info_p->st_gid) );
    printf( "%8ld " , (long)info_p->st_size);
    printf( "%.12s ", 4+ctime(&info_p->st_mtime));
    printf( "%sn"  , filename );
}
/*
 * utility functions
 */
/*
 * This function takes a mode value and a char array
 * and puts into the char array the file type and the 
 * nine letters that correspond to the bits in mode.
 * NOTE: It does not code setuid, setgid, and sticky
 * codes
 */
void mode_to_letters( int mode, char str[] )
{
    strcpy( str, "----------" );           /* default=no perms */
    if ( S_ISDIR(mode) )  str[0] = 'd';    /* directory?       */
    if ( S_ISCHR(mode) )  str[0] = 'c';    /* char devices     */
    if ( S_ISBLK(mode) )  str[0] = 'b';    /* block device     */
    if ( mode & S_IRUSR ) str[1] = 'r';    /* 3 bits for user  */
    if ( mode & S_IWUSR ) str[2] = 'w';
    if ( mode & S_IXUSR ) str[3] = 'x';
    if ( mode & S_IRGRP ) str[4] = 'r';    /* 3 bits for group */
    if ( mode & S_IWGRP ) str[5] = 'w';
    if ( mode & S_IXGRP ) str[6] = 'x';
    if ( mode & S_IROTH ) str[7] = 'r';    /* 3 bits for other */
    if ( mode & S_IWOTH ) str[8] = 'w';
    if ( mode & S_IXOTH ) str[9] = 'x';
}
#include    <pwd.h>
char *uid_to_name( uid_t uid )
/* 
 *  returns pointer to username associated with uid, uses getpw()
 */ 
{
    struct  passwd *getpwuid(), *pw_ptr;
    static  char numstr[10];
    if ( ( pw_ptr = getpwuid( uid ) ) == NULL ){
        sprintf(numstr,"%d", uid);
        return numstr;
    }
    else
        return pw_ptr->pw_name ;
}
#include    <grp.h>
char *gid_to_name( gid_t gid )
/*
 *  returns pointer to group number gid. used getgrgid(3)
 */
{
    struct group *getgrgid(), *grp_ptr;
    static  char numstr[10];
    if ( ( grp_ptr = getgrgid(gid) ) == NULL ){
        sprintf(numstr,"%d", gid);
        return numstr;
    }
    else
        return grp_ptr->gr_name;
}

Answer 1

这一行：

( argv[0])

正在从传递的参数中提取第一个字符。

建议：

( argv )

因此，获取指向传递给函数的 NUl 终止字符串的指针。