[英]recursive folder scanning in c++
I want to scan a directory tree and list all files and folders inside each directory. 我想扫描目录树并列出每个目录中的所有文件和文件夹。 I created a program that downloads images from a webcamera and saves them locally.
我创建了一个程序,可从网络摄像机下载图像并将其保存在本地。 This program creates a filetree based on the time the picture is downloaded.
该程序根据图片的下载时间创建文件树。 I now want to scan these folders and upload the images to a webserver but I´m not sure how I can scan the directories to find the images.
我现在想扫描这些文件夹并将图像上传到Web服务器,但是我不确定如何扫描目录以查找图像。 If anyone could post some sample code it would be very helpful.
如果有人可以张贴一些示例代码,那将非常有帮助。
edit : I´m running this on an embedded linux system and don´t want to use boost 编辑 :我在嵌入式linux系统上运行它,不想使用boost
See man ftw
for a simple "file tree walk". 有关简单的“文件树遍历”,请参见
man ftw
。 I also used fnmatch
in this example. 在此示例中,我还使用了
fnmatch
。
#include <ftw.h>
#include <fnmatch.h>
static const char *filters[] = {
"*.jpg", "*.jpeg", "*.gif", "*.png"
};
static int callback(const char *fpath, const struct stat *sb, int typeflag) {
/* if it's a file */
if (typeflag == FTW_F) {
int i;
/* for each filter, */
for (i = 0; i < sizeof(filters) / sizeof(filters[0]); i++) {
/* if the filename matches the filter, */
if (fnmatch(filters[i], fpath, FNM_CASEFOLD) == 0) {
/* do something */
printf("found image: %s\n", fpath);
break;
}
}
}
/* tell ftw to continue */
return 0;
}
int main() {
ftw(".", callback, 16);
}
(Not even compile-tested, but you get the idea.) (甚至没有经过编译测试,但是您知道了。)
This is much simpler than dealing with DIRENT
s and recursive traversal yourself. 这比自己处理
DIRENT
和递归遍历要简单得多。
For greater control over traversal, there's also fts
. 为了更好地控制遍历,还可以使用
fts
。 In this example, dot-files (files and directories with names starting with ".") are skipped, unless explicitly passed to the program as a starting point. 在此示例中,点文件(名称以“。”开头的文件和目录)将被跳过,除非作为起点明确传递给程序。
#include <fts.h>
#include <string.h>
int main(int argc, char **argv) {
char *dot[] = {".", 0};
char **paths = argc > 1 ? argv + 1 : dot;
FTS *tree = fts_open(paths, FTS_NOCHDIR, 0);
if (!tree) {
perror("fts_open");
return 1;
}
FTSENT *node;
while ((node = fts_read(tree))) {
if (node->fts_level > 0 && node->fts_name[0] == '.')
fts_set(tree, node, FTS_SKIP);
else if (node->fts_info & FTS_F) {
printf("got file named %s at depth %d, "
"accessible via %s from the current directory "
"or via %s from the original starting directory\n",
node->fts_name, node->fts_level,
node->fts_accpath, node->fts_path);
/* if fts_open is not given FTS_NOCHDIR,
* fts may change the program's current working directory */
}
}
if (errno) {
perror("fts_read");
return 1;
}
if (fts_close(tree)) {
perror("fts_close");
return 1;
}
return 0;
}
Again, it's neither compile-tested nor run-tested, but I thought I'd mention it. 同样,它既没有经过编译测试也没有运行测试,但我想我已经提到了。
Boost.Filesystem allows you to do that. Boost.Filesystem允许您执行此操作。 Check out the docs !
查看文档 !
EDIT: 编辑:
If you are using Linux and you don't want to use Boost, you will have to use the Linux native C functions. 如果您使用的是Linux,并且不想使用Boost,则必须使用Linux本机C函数。 This page shows many examples on how to do just that.
此页面显示了有关如何执行此操作的许多示例。
I'm old school, no ftw() for me! 我是老学校,对我没有ftw()! This is crude (it's been a while since I did straight C programming), and lots of stuff is hardcoded, and I probably messed up my length calculations for the strnc*() functions, but you get the idea.
这很粗糙(自从我进行直接C编程以来已经有一段时间了),并且很多东西都是硬编码的,而且我可能弄乱了strnc *()函数的长度计算,但是您明白了。 There's a similar example in K&R btw.
K&R btw中有一个类似的例子。
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <dirent.h>
void listdir(char* dirname, int lvl);
int main(int argc, char** argv)
{
if (argc != 2) {
fprintf(stderr, "Incorrect usage!\n");
exit(-1);
}
listdir(argv[1], 0);
return 0;
}
void listdir(char* dirname, int lvl)
{
int i;
DIR* d_fh;
struct dirent* entry;
char longest_name[4096];
while( (d_fh = opendir(dirname)) == NULL) {
fprintf(stderr, "Couldn't open directory: %s\n", dirname);
exit(-1);
}
while((entry=readdir(d_fh)) != NULL) {
/* Don't descend up the tree or include the current directory */
if(strncmp(entry->d_name, "..", 2) != 0 &&
strncmp(entry->d_name, ".", 1) != 0) {
/* If it's a directory print it's name and recurse into it */
if (entry->d_type == DT_DIR) {
for(i=0; i < 2*lvl; i++) {
printf(" ");
}
printf("%s (d)\n", entry->d_name);
/* Prepend the current directory and recurse */
strncpy(longest_name, dirname, 4095);
strncat(longest_name, "/", 4095);
strncat(longest_name, entry->d_name, 4095);
listdir(longest_name, lvl+1);
}
else {
/* Print some leading space depending on the directory level */
for(i=0; i < 2*lvl; i++) {
printf(" ");
}
printf("%s\n", entry->d_name);
}
}
}
closedir(d_fh);
return;
}
You will want to use the directory functions declared in dirent.h. 您将要使用dirent.h中声明的目录功能。 This wikipedia page describes them and includes sample code.
此Wikipedia页面描述了它们并包括示例代码。 For your application, once you have identified a directory, you will want to call the processing function again recursively to process the directory contents.
对于您的应用程序,一旦确定了目录,您将希望再次递归调用处理函数以处理目录内容。
您也可以使用glob / globfree。
I think if you can use Qt/Embedded, there are QDir and QFileInfo classes which can help you, though it depends if you can use the Qt. 我认为,如果可以使用Qt / Embedded,则有QDir和QFileInfo类可以为您提供帮助,尽管这取决于您是否可以使用Qt。 The question is which API your system provides.
问题是您的系统提供哪种API。
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