check_parent_exists.cc

.cc

#include <iostream>

#include <experimental/filesystem>

namespace fs = std::experimental::filesystem;

void ensure_parent_exists(const std::string& filepath) {
    fs::path p(filepath);
    fs::path parent = p.parent_path();
    
    if (!parent.empty() && !fs::exists(parent)) {
        std::cout << "Creating directory: " << parent << std::endl;
        fs::create_directories(parent);
    }
}

void ensure_parent_exists2(const std::string& filepath) {
    fs::create_directories(fs::path(filepath).parent_path());
}

int main() {
    ensure_parent_exists2("./tmp/subdir/file.txt");
    return 0;
}

// g++ test_fs.cpp   -std=c++11 -lstdc++fs