Get parent directory from file in C++ - c++

Question

I need to get parent directory from file in C++:
For example:
Input:
D:\Devs\Test\sprite.png
Output:
D:\Devs\Test\ [or D:\Devs\Test]
I can do this with a function:
char *str = "D:\\Devs\\Test\\sprite.png";
for(int i = strlen(str) - 1; i>0; --i)
{
if( str[i] == '\\' )
{
str[i] = '\0';
break;
}
}
But, I just want to know there is exist a built-in function.
I use VC++ 2003.
Thanks in advance.

Answer 1

If you're using std::string instead of a C-style char array, you can use string::find_last_of and string::substr in the following manner:
std::string str = "D:\\Devs\\Test\\sprite.png";
str = str.substr(0, str.find_last_of("/\\"));

Answer 2

Now, with C++17 is possible to use std::filesystem::path::parent_path:
#include <filesystem>
namespace fs = std::filesystem;
int main() {
fs::path p = "D:\\Devs\\Test\\sprite.png";
std::cout << "parent of " << p << " is " << p.parent_path() << std::endl;
// parent of "D:\\Devs\\Test\\sprite.png" is "D:\\Devs\\Test"
std::string as_string = p.parent_path().string();
return 0;
}

Answer 3

Heavy duty and cross platform way would be to use boost::filesystem::parent_path(). But obviously this adds overhead you may not desire.
Alternatively you could make use of cstring's strrchr function something like this:
include <cstring>
char * lastSlash = strrchr( str, '\\');
if ( *lastSlash != '\n') *(lastSlash +1) = '\n';

Answer 4

Editing a const string is undefined behavior, so declare something like below:
char str[] = "D:\\Devs\\Test\\sprite.png";
You can use below 1 liner to get your desired result:
*(strrchr(str, '\\') + 1) = 0; // put extra NULL check before if path can have 0 '\' also

Answer 5

On POSIX-compliant systems (*nix) there is a commonly available function for this dirname(3). On windows there is _splitpath.
The _splitpath function breaks a path
into its four components.
void _splitpath(
const char *path,
char *drive,
char *dir,
char *fname,
char *ext
);
So the result (it's what I think you are looking for) would be in dir.
Here's an example:
int main()
{
char *path = "c:\\that\\rainy\\day";
char dir[256];
char drive[8];
errno_t rc;
rc = _splitpath_s(
path, /* the path */
drive, /* drive */
8, /* drive buffer size */
dir, /* dir buffer */
256, /* dir buffer size */
NULL, /* filename */
0, /* filename size */
NULL, /* extension */
0 /* extension size */
);
if (rc != 0) {
cerr << GetLastError();
exit (EXIT_FAILURE);
}
cout << drive << dir << endl;
return EXIT_SUCCESS;
}

Answer 6

On Windows platforms, you can use
PathRemoveFileSpec or PathCchRemoveFileSpec
to achieve this.
However for portability I'd go with the other approaches that are suggested here.

Answer 7

You can use dirname to get the parent directory
Check this link for more info
Raghu