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Problem when generate ID from txt file

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Join Date: Nov 2009

Posts: 2

Reputation: just4why is an unknown quantity at this point

Solved Threads: 0

just4why

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Newbie Poster

Problem when generate ID from txt file

29 Days Ago

I would like to automatically generated staff number before generated the staff number i would like to check the staff.txt is the staff number exist. If exist then it will get the last's staff number and continue to adding. But the code that i creating it wont work. Please help to me rewrite.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
void staff::setstaffid()
{
	int count = 0;
 
	ifstream instaffile("staff.txt", ios::in);
 
		if(!instaffile)
		{
			ofstream outstaffile("staff.txt", ios::out);
			outstaffile.close();
 
			ifstream instaffile("staff.txt", ios::in);
		}
 
		instaffile.read(reinterpret_cast<char *>(this), sizeof(staff));
 
		if(instaffile.eof())						//if the staff id is 0 then it will start from 20000
		{
			staffid = 1;
			return;
		}
		else
		{
			while(instaffile && !instaffile.eof())
			{
				count++;
				instaffile.read(reinterpret_cast<char *>(this),sizeof(staff));
			}
		}
 
		staffid = 1 + (count);					//increment the staff id
 
		instaffile.close();
		return;
}
void staff::setstaffid()
{
	int count = 0;

	ifstream instaffile("staff.txt", ios::in);

		if(!instaffile)
		{
			ofstream outstaffile("staff.txt", ios::out);
			outstaffile.close();

			ifstream instaffile("staff.txt", ios::in);
		}

		instaffile.read(reinterpret_cast<char *>(this), sizeof(staff));

		if(instaffile.eof())						//if the staff id is 0 then it will start from 20000
		{
			staffid = 1;
			return;
		}
		else
		{
			while(instaffile && !instaffile.eof())
			{
				count++;
				instaffile.read(reinterpret_cast<char *>(this),sizeof(staff));
			}
		}

		staffid = 1 + (count);					//increment the staff id

		instaffile.close();
		return;
}

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Join Date: Aug 2005

Posts: 15,412

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Ancient Dragon Ancient Dragon is offline

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Still Learning

-7

29 Days Ago

line 17 is probably the wrong way to determine if the file is empty or not. What you should do is seek to end of file then get the file position.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
instaffile.seekg(0, ios::end);
size_t sz = instaffile.tellg();
if( sz == 0)
{
    staffid = 1;
    return;
}
instaffile.seekg(0, ios::end);
size_t sz = instaffile.tellg();
if( sz == 0)
{
    staffid = 1;
    return;
}

The loop at lines 24-28 is also wrong

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
instaffile.seekp(0, ios::beg); // go to beginning of tile
count = 0;
while( instaffile.read(reinterpret_cast<char *>(this),sizeof(staff))
{
     ++count;
}
instaffile.seekp(0, ios::beg); // go to beginning of tile
count = 0;
while( instaffile.read(reinterpret_cast<char *>(this),sizeof(staff))
{
     ++count;
}