list problem

[RobBinS]

I use one list<string> object to store the file names in one directory. There is a function called ScanDiretory(list) which adds file names into the list. In the end of this function, I check list.size(), nothing was wrong. But just after the function finished, I rechecked the size, it return 0.
Here is the codes

bool ScanDirectory(string _dirname,string _fnmp, list<string> _lname)
{
	DIR *dir;
	struct dirent *ent;
	size_t found;
	string fn,ext;

	dir = opendir (_dirname.c_str());

	if(dir != NULL)
	{
		cout<<"Open directory <"<<_dirname<<"> successfully!"<<endl;

		while ((ent = readdir (dir)) != NULL) 
		{
			//		printf ("%s\n", ent->d_name);

			string tmp;
			tmp = ent->d_name;

			found = tmp.find_last_of(".");
			if(found!=tmp.npos)
			{
				fn = tmp.substr(0,found);
				ext = tmp.substr(found+1);
				if(fn==_fnmp)
				{
					_lname.push_back(tmp); //add to the list
			//		printf ("%s  %s\n",fn.c_str(),ext.c_str());
				}
			}
		}
		
		_lname.sort();
		cout<<"Scan directory <"<<_dirname<<"> finished!"<<endl;
		cout<<(int)_lname.size()<<" mean path files were found."<<endl;
		
		for(list<string>::iterator it=_lname.begin();it!=_lname.end();it++)
			cout<<*it<<endl;

	//	cout<<(int)_lname.size()<<" mean path files were found."<<endl;

		closedir(dir);
		return true;
	}
	else
	{
		cout<<"Can not open directory <"<<_dirname<<">"<<endl;
		return false;
	}
}

[jsmith]

You aren't returning the list to the caller.

[RobBinS]

Can you explain more in details? I'm not quite sure what you mean.

[Galik]

This function signature...

bool ScanDirectory(string _dirname,string _fnmp, list<string> _lname)
{
    // ...
}

... passes a copy of your list _lname into the function. That copy is destroyed when your function exits.

In order to change the original list that you pass in you need to pass it by reference rather than a copy.

bool ScanDirectory(string _dirname,string _fnmp, list<string>& _lname)
{
    // ...
}

That way when the function adds elements to _lname it is adding them to the one you passed in rather than a copy.

[RobBinS]

Thanks. Got it.