Get a List of Files in the Directory in C++

Getting a list of files in a given directory is some of the most common and basic computer usage tasks. As a developer, it is, therefore, reasonable to understand how file listing in a directory works.

In this tutorial, we cover some methods of implementing a program that lists the files and directories of a given directory using C++.

Using the filesystem::directory_iterator

In C++ 17 and above, we have access to the directory_iteratormethod from the filesystem package. As the name suggests, this method performs an iteration, going through each item in a given directory one after another.

The method takes the path to the target directory as the argument. We can use the method as the argument for` a loop to iterate over each file and directory in the target path.

Example code:

//
//  main.cpp
//  GeekBits
//
//  Created by captain on 01/12/2022.
//

#include <iostream>
#include <filesystem>
#include <string>
#include <vector>

using std::cin; using std::cout;
using std::filesystem::directory_iterator;
using std::endl; using std::string;


int main(int argc, const char * argv[]) {
    string directory_path = "/Users/csalem/Desktop";
    for (const auto & file: directory_iterator(directory_path)) {
        cout << file.path() << endl;
    }
    return 0;
}

Once we run the code above, we should get the path of the files and directories in the target path. An example output is as shown:

"/Users/csalem/Desktop/Developer"
"/Users/csalem/Desktop/.DS_Store"
"/Users/csalem/Desktop/.localized"
"/Users/csalem/Desktop/articles"
"/Users/csalem/Desktop/GeekBits"
"/Users/csalem/Desktop/codes"
"/Users/csalem/Desktop/temp_files"
Program ended with exit code: 0

Note that the output may vary depending on your target directory.

Using the std::filesystem::recursive_directory_iterator

We can also use the recursive_directory_iterator method to fetch the list of files and directories. This method behaves similarly to the directory_iterator. However, it is useful when working with subdirectories where you need to search for specific filenames.

Example code:

//
//  main.cpp
//  GeekBits
//
//  Created by captain on 01/12/2022.
//

#include <iostream>
#include <filesystem>
#include <string>
#include <vector>

using std::cin; using std::cout;
using std::filesystem::recursive_directory_iterator;
using std::endl; using std::string;


int main(int argc, const char * argv[]) {
    string directory_path = "/Users/csalem/Desktop";
    for (const auto & file: recursive_directory_iterator(directory_path)) {
        cout << file.path() << endl;
    }
    return 0;
}

Running the code above should allow the program to list all the files and directories even in multiple subdirectories as:

"/Users/csalem/Desktop/Developer"
"/Users/csalem/Desktop/Developer/test_variable.sh"
"/Users/csalem/Desktop/Developer/passkeep.py"
"/Users/csalem/Desktop/Developer/test.py"
"/Users/csalem/Desktop/Developer/sender.java"
"/Users/csalem/Desktop/Developer/nanproduct.py"
"/Users/csalem/Desktop/Developer/fs.cpp"
"/Users/csalem/Desktop/Developer/main.py"
"/Users/csalem/Desktop/.DS_Store"
"/Users/csalem/Desktop/.localized"
"/Users/csalem/Desktop/GeekBits"
"/Users/csalem/Desktop/GeekBits/.DS_Store"
"/Users/csalem/Desktop/GeekBits/GeekBits.xcodeproj"
"/Users/csalem/Desktop/GeekBits/GeekBits.xcodeproj/project.pbxproj"
"/Users/csalem/Desktop/GeekBits/GeekBits.xcodeproj/xcuserdata"
"/Users/csalem/Desktop/GeekBits/GeekBits.xcodeproj/xcuserdata/csalem.xcuserdatad"
"/Users/csalem/Desktop/GeekBits/GeekBits.xcodeproj/xcuserdata/csalem.xcuserdatad/xcschemes"
"/Users/csalem/Desktop/GeekBits/GeekBits.xcodeproj/xcuserdata/csalem.xcuserdatad/xcschemes/xcschememanagement.plist"
"/Users/csalem/Desktop/GeekBits/GeekBits.xcodeproj/project.xcworkspace"
"/Users/csalem/Desktop/GeekBits/GeekBits.xcodeproj/project.xcworkspace/contents.xcworkspacedata"
"/Users/csalem/Desktop/GeekBits/GeekBits.xcodeproj/project.xcworkspace/xcuserdata"
"/Users/csalem/Desktop/GeekBits/GeekBits.xcodeproj/project.xcworkspace/xcuserdata/csalem.xcuserdatad"
"/Users/csalem/Desktop/GeekBits/GeekBits.xcodeproj/project.xcworkspace/xcuserdata/csalem.xcuserdatad/UserInterfaceState.xcuserstate"
"/Users/csalem/Desktop/GeekBits/GeekBits.xcodeproj/project.xcworkspace/xcshareddata"
"/Users/csalem/Desktop/GeekBits/GeekBits.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist"
"/Users/csalem/Desktop/GeekBits/GeekBits.xcodeproj/project.xcworkspace/xcshareddata/swiftpm"
"/Users/csalem/Desktop/GeekBits/GeekBits.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/configuration"
"/Users/csalem/Desktop/GeekBits/GeekBits"
"/Users/csalem/Desktop/GeekBits/GeekBits/main.cpp"
"/Users/csalem/Desktop/codes"
"/Users/csalem/Desktop/codes/geekbits.http"
"/Users/csalem/Desktop/codes/string_conversion.java"
"/Users/csalem/Desktop/codes/byte_array_to_string.go"
"/Users/csalem/Desktop/codes/table.cql"

Using the opendir/readdir Functions

We can also use the opendir and readdir functions from the direct.h header file to read files in a given directory. As the name suggests, the opendir opens the directory at the specified path and returns a DIR* pointer, while the readdir method operates the DIR* pointer and returns the pointer and returns a structure that represents the next directory entry in the directory stream.

You can learn more here -> https://www.man7.org/linux/man-pages/man3/readdir.3.html

We can put the readdirfunction on a while loop and compare the nullptr which works as directory iterator. We can then fetch the filenames from the struct of the function.

Example:

//
//  main.cpp
//  GeekBits
//
//  Created by captain on 01/12/2022.
//

#include <iostream>
#include <vector>
#include <dirent.h>

using std::cin; using std::cout; using std::endl;
using std::vector;

int main(int argc, const char * argv[]) {
    DIR *dir_ptr;
    struct dirent *diread;
    vector<char *> filenames;
    if ((dir_ptr = opendir("/Users/csalem/Desktop")) != nullptr) {
        while ((diread = readdir(dir_ptr)) != nullptr) {
            filenames.push_back(diread->d_name);
        }
        closedir(dir_ptr);
    } else {
        perror("fail");
        return -1;
    }
    for (auto file: filenames) {
        cout << file << "";
        cout << endl;
    }
    return 0;
}

Output:

.
..
Developer
.DS_Store
.localized
articles
GeekBits
codes
temp_files
Program ended with exit code: 0

Conclusion

In this tutorial, you discovered three main methods for fetching files and listing a given directory in C++.