Question

i’m new in c++ world, i just use it for litle app that help me in my work, now, i need to read the content of a folder, list the folder content, i’ve made a function that return a pointer with the name of every obj in the folder, but now, i don’t know how to read the content of the pointer to just print it in a console, my function look like this

string* listdir (const char *path)
{
    string* result = new string[50]; // limit to 50 obj
    DIR *pdir = NULL;
    pdir = opendir (path);
    struct dirent *pent = NULL;
    if (pdir == NULL)
    { 
        printf ("\nERROR! pdir could not be initialised correctly");
        return NULL;
    } 
    int i = 0;
    while (pent = readdir (pdir))
    {
        if (pent == NULL)
        {
            printf ("\nERROR! pent could not be initialised correctly");
            return NULL;
        }
        //printf ("%s\n", pent->d_name);
        result[i++]= pent->d_name;
    }

    closedir (pdir);
    return result;
}

i’ve been trying to print the result of teh function

int main()
{
    string *dirs;
    dirs = listdir("c:\\");
    int i = 0;
    //while(dirs[i])
    //{
            //cout<<dirs[i]<<'\n';
            //++i;
    //}
}

but i really don’t know what i’m doing, lol, some help would be perfect
thanks

Answer 1

In C++, dereferencing a pointer is achieved using the * operator, just like in ‘C’.

However, there are a number of problems with your code, which I have addressed here because I was bored…

#include <string>
#include <iostream>
#include <list>
#include <dirent.h>

typedef std::list<std::string> dir_list;

bool listdir(const std::string& path, dir_list& result)
{
    bool retval = true;
    DIR* pdir = opendir(path.c_str());
    if (pdir == NULL)
    {
        std::cerr << "ERROR! pdir could not be initialised correctly" << std::endl;;
        retval = false;
    }
    else
    {
        for (dirent* pent = readdir(pdir); pent != NULL; pent = readdir(pdir))
        {
            if (pent == NULL && result.empty())
            {
                std::cerr << "ERROR! pent could not be initialised correctly" << std::endl;
                retval = false;
            }

            if (result.size() < 50)
            {// *really* limit to 50!
                result.push_back(pent->d_name);
            }
        }
        closedir(pdir);
    }
    return retval;
}

int main()
{
    dir_list dirs;
    if (listdir("C:/", dirs))
    {
        for (dir_list::const_iterator iter(dirs.begin()), end(dirs.end()); iter != end; ++iter)
        {
            std::cout << *iter << std::endl;
        }
    }
}

Since you’re using C++, STL, its string and container classes will save you a World of pointer pain!