Create a directory if it doesn't exist - c++

Question

In my app I want to copy a file to the other hard disk so this is my code:
#include <windows.h>
using namespace std;
int main(int argc, char* argv[] )
{
string Input = "C:\\Emploi NAm.docx";
string CopiedFile = "Emploi NAm.docx";
string OutputFolder = "D:\\test";
CopyFile(Input.c_str(), string(OutputFolder+CopiedFile).c_str(), TRUE);
return 0;
}
so after executing this, it shows me in the D:HDD a file testEmploi NAm.docx
but I want him to create the test folder if it doesn't exist.
I want to do that without using the Boost library.

Answer 1

Use the WINAPI CreateDirectory() function to create a folder.
You can use this function without checking if the directory already exists as it will fail but GetLastError() will return ERROR_ALREADY_EXISTS:
if (CreateDirectory(OutputFolder.c_str(), NULL) ||
ERROR_ALREADY_EXISTS == GetLastError())
{
// CopyFile(...)
}
else
{
// Failed to create directory.
}
The code for constructing the target file is incorrect:
string(OutputFolder+CopiedFile).c_str()
this would produce "D:\testEmploi Nam.docx": there is a missing path separator between the directory and the filename. Example fix:
string(OutputFolder+"\\"+CopiedFile).c_str()

Answer 2

#include <experimental/filesystem> // or #include <filesystem> for C++17 and up
namespace fs = std::experimental::filesystem;
if (!fs::is_directory("src") || !fs::exists("src")) { // Check if src folder exists
fs::create_directory("src"); // create src folder
}

Answer 3

Probably the easiest and most efficient way is to use boost and the boost::filesystem functions. This way you can build a directory simply and ensure that it is platform independent.
const char* path = _filePath.c_str();
boost::filesystem::path dir(path);
if(boost::filesystem::create_directory(dir))
{
std::cerr<< "Directory Created: "<<_filePath<<std::endl;
}
boost::filesystem::create_directory - documentation

Answer 4

Here is the simple way to create a folder.......
#include <windows.h>
#include <stdio.h>
void CreateFolder(const char * path)
{
if(!CreateDirectory(path ,NULL))
{
return;
}
}
CreateFolder("C:\\folder_name\\")
This above code works well for me.

Answer 5

_mkdir will also do the job.
_mkdir("D:\\test");
https://msdn.microsoft.com/en-us/library/2fkk4dzw.aspx

Answer 6

OpenCV Specific
Opencv supports filesystem, probably through its dependency Boost.
#include <opencv2/core/utils/filesystem.hpp>
cv::utils::fs::createDirectory(outputDir);

Answer 7

Since c++17, you can easily do this cross-platform with:
#include <filesystem>
int main() {
auto created_new_directory
= std::filesystem::create_directory("directory_name");
if (not created_new_directory) {
// Either creation failed or the directory was already present.
}
}
Note, that this version is very useful, if you need to know, whether the directory is actually newly created.
And I find the documentation on cppreference slightly difficult to understand on this point: If the directory is already present, this function returns false.
This means, you can more or less atomically create a new directory with this method.

Answer 8

Use CreateDirectory (char *DirName, SECURITY_ATTRIBUTES Attribs);
If the function succeeds it returns non-zero otherwise NULL.

Answer 9

You can use cstdlib
Although- http://www.cplusplus.com/articles/j3wTURfi/
#include <cstdlib>
const int dir= system("mkdir -p foo");
if (dir< 0)
{
return;
}
you can also check if the directory exists already by using
#include <dirent.h>

Answer 10

This works in GCC:
Taken from:
Creating a new directory in C
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
struct stat st = {0};
if (stat("/some/directory", &st) == -1) {
mkdir("/some/directory", 0700);
}