我想编一段c程序：在/mnt/usb目录里，找出扩展名为plt的文件？怎么做？给点提示或编程的思路。谢谢帮助！

一个粗糙的版本, 有错请告知, 谢了, :-)

void walkdir(const char *dirname)
{
        char dname[PATH_MAX + 1];
        int mode;
        struct stat sbuf;
        struct dirent *direntp;
        DIR *dirp;
        char *p;
        int len;

        if (lstat(dirname, &sbuf) != 0)
                return ;
        mode = sbuf.st_mode;

        if (S_ISDIR(mode)) {
                if ((dirp = opendir(dirname)) == NULL)
                        return ;
                while ((direntp = readdir(dirp)) != NULL) {
                        if (strcmp(direntp->d_name, ".") && strcmp(direntp->d_name, "..")) {
                                strcpy(dname, dirname);
                                if (strcmp(dirname, "/"))
                                        strcat(dname, "/");
                                strcat(dname, direntp->d_name);
                                walkdir(dname);
                        }
                }
                closedir(dirp);
                return ;
        } else {
                if (S_ISREG(mode)) {
                        if ((len = strlen(dirname)) >= 4) {
                                p = (char *)(dirname + len - 4);
                                if (!strcmp(p, ".plt")) {
                                        printf("%sn", dirname);
                                }
                        }
                }
        }
}

static void findfile( void )
{
#define SUFFIX ".plt"
#define DIRRE "/mnt/usb"

 int i = 0;
 DIR *dirp; struct dirent *dp;
 int suffixlen = strlen( SUFFIX );

 dirp = opendir( DIRRE );
 if( !dirp ){
    perror("opendir");
    return -1;
 }
 while( (dp = readdir(dirp)) != NULL ){
     if( strncmp(dp->d_name+(dp->d_namlen - suffixlen),
                       SUFFIX, suffixlen) == 0 ){ /* find */
         fprintf( stderr, "[%s] found.n", db->d_name );
     }
}

(void)closedir( dirp );
}