问题描述
我希望拥有超过一百万个具有唯一名称的文件。我被告知,如果我将所有这些文件放在一个或两个目录中,这些文件的搜索速度将会非常慢。所以我想出了以下目录结构。
i expect to have more than one million files with unique names. I have been told that if i put all this files in one or two directories the search speed for these files will be extremely slow. So i have come up with the following directory architecture.
我希望目录结构能够分支出10个子目录,子目录的级别将为4.因为文件名保证是唯一的,我想使用这些文件名来创建可用于将文件放在目录中的哈希值,以后再找到它们。随机哈希值将使一个目录具有大约1,000个文件。
I want the directory structure to branch out with 10 sub directories and the level of the sub directories will be 4. because the file names are guaranteed to be unique i want to use these file names to make hashes which can be used to put the file in a directory and also later to find it. The random hash values will make a directory to have,approximately, 1,000 files.
所以如果F是根目录,那么插入或搜索文件将不得不经过以下步骤:
so if F is root directory then inserting or searching for a file will have to go through these steps:
我想使用0-9的数字作为目录名
I want to use numbers from 0-9 as directory names
h=hash(filename)
sprintf(filepath,"f//%d//%d//%d//%d//.txt",h%10,h%10,h%10,h%10);
我如何创建这些董事?
编辑:
所有文件都是文本文件。
该计划将分发给许多人,以收集研究信息。所以tt很重要,这些文件是这样创建的。
All the files are text files.The program will be distributed to many people in order to collect information for a research. So tt is important that these files are created like this.
编辑:
我创建了以下代码实施 perreal的伪代码。它编译成功,但给出最后给出的运行时错误。
错误发生在 sprintf()
行。
i created the following code to implement perreal's pseudo code. It compiles to success but gives the run time error given at the end.error occurs at the sprintf()
line.
#include<iostream>
#include<stdlib.h>
#include<windows.h>
void make_dir(int depth, char *dir) {
if (depth < 4) {
if (! CreateDirectoryA (dir,NULL))
for (int i = 0; i < 10; i++) {
sprintf(dir,"\\%d",i);
char *sdir=NULL ;
strcpy(sdir,dir);
CreateDirectoryA(sdir,NULL);
make_dir(depth + 1, sdir);
}
}
}
int main()
{
make_dir(0,"dir");
return 1;
}
推荐答案
类型的伪代码,但可以这样做:
Kind of pseudo code, but can be done like this:
void make_dir(int depth, char *dir) {
if (depth < 4) {
CreateDirectoryA (dir,NULL);
for (int i = 0; i < 10; i++) {
char *sdir= (char*)malloc(strlen(dir+10)); // XXX 10?
strcpy(sdir, dir);
sprintf(sdir + strlen(sdir), "\\%d", i);
printf("%s\n", sdir);
//CreateDirectoryA(sdir,NULL);
make_dir(depth + 1, sdir);
free(sdir);
}
}
}
}
并调用 make_dir(0,rootdir);
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