Creating folders in C++

问题

I have recently started working in C++ and came across this situation when I have to create a directory while executing my code. The code is working fine when I have to create a single folder but it fails when I have to create another folder withing this newly created folder.

Suppose, I am in C: and want to store my file in C:/A/B/ .The following piece of code using mkdir() works fine if I have to store my file in C:/A/ but fails when I am adding another folder B.

Following is my code snippet:

#include <sys/stat.h>
#include <string>
using namespace std;

int main()
{
    string stringpath = "C:/A/B/"; 
    int status = mkdir(stringpath.c_str(),0777);

    if(status!=0)
    {
        //.....
    }
    else
    {
        //....
    }
}

Can someone help me in creating this directory where I can have any number of folders inside the parent directory? (P.S:I have added the header files sys/stat.h,iostream and string)

回答1:

This is how you do it in C++17:

#include <filesystem>
namespace fs = std::filesystem;
fs::create_directories("./a/b/c")

回答2:

mkdir() creates only the last component of the specified path. In your example, it will create only B. If any of the parent directories do not exist (ie, if A does not exist), the function fails with ENOENT. You need to split up the path and call mkdir() for every intermediate directory in the path, ignoring EEXIST errors as you go.

status = mkdir("C:/A/", 0777);
if ((status < 0) && (errno != EEXIST)) ...

status = mkdir("C:/A/B/", 0777);
if ((status < 0) && (errno != EEXIST)) ...

If you don't want to handle this manually, use a wrapper that handles it for you, such as Boost's create_directories() function:

bool create_directories(const path& p);
bool create_directories(const path& p, system::error_code& ec);

Effects: Establishes the postcondition by calling create_directory() for any element of p that does not exist.

Postcondition: is_directory(p)

Returns: true if a new directory was created, otherwise false.

Throws: As specified in Error reporting.

Complexity: O(n+1)where n is the number of elements of p that do not exist.

回答3:

You can call the following:

string stringpath = "C:/A/B/";
int status = mkdir(stringpath.c_str(),0777);

If C:/A/ directory exists. If its not exists, then do the following:

string stringpath = "C:/A/";
int status = mkdir(stringpath.c_str(),0777);
stringpath = "C:/A/B/";
int status = mkdir(stringpath.c_str(),0777);

回答4:

In C++11 you can use the experimental functios:

#include <experimental/filesystem>
...
std::stringstream bufH;
bufH << dirName << fName;
if (!std::experimental::filesystem::exists(bufH.str()))
{
 std::experimental::filesystem::create_directories(bufH.str());
}

来源：https://stackoverflow.com/questions/50960492/creating-folders-in-c

标签

c++

c++11

filesystems