Thread: file streams

Would anyone be able to help me with the following problem. I am trying to create a generic function, which accepts a stream name and the file name to open. The function output an error if it can't open the file. I've written some sample code to try and illustrate what I mean. Any ideas would be v.greatful thanks.

#include <iostream.h>
#include <fstream.h>

const int MAX_BUFFER=256;

void OpenFile(ifstream InFile, char FileName[MAX_BUFFER]);

int main()
{
char FileName[MAX_BUFFER]="Test.txt";

ifstream InFile;

OpenFile(InFile,FileName);
getchar();

return 0;
}

void OpenFile(ifstream InFile, char FileName[MAX_BUFFER])
{
InFile.open(FileName);

if(Infile.fail())
cout << "\nCould not open file.";
}

Can someone please help me on this, I can't make the streams global.

Try it like this.

#include <iostream.h>
#include <fstream.h>

const int MAX_BUFFER=256;

void OpenFile(ifstream &InFile, char FileName[MAX_BUFFER]);

int main()
{
char FileName[MAX_BUFFER]="Test.txt";

ifstream InFile;

OpenFile(InFile,FileName);
getchar();

return 0;
}

void OpenFile(ifstream &InFile, char FileName[MAX_BUFFER])
{
InFile.open(FileName);

if(InFile.fail())
cout << "\nCould not open file.";
}

..or this -

Code:

#include <iostream> 
#include <fstream>

using namespace std;

const int MAX_BUFFER=256; 

void OpenFile(ifstream &InFile, char FileName[MAX_BUFFER]); 

int main() 
{ 
	char FileName[MAX_BUFFER]="Test.txt"; 

	ifstream InFile; 

	OpenFile(InFile,FileName); 
	getchar(); 

	return 0; 
} 

void OpenFile(ifstream &InFile, char FileName[MAX_BUFFER]) 
{ 
	InFile.open(FileName); 

	if(!InFile.is_open()) 
		cout << "\nCould not open file."; 
}

You should use the standard headers, otherwise you'll have to set flags to prevent automatic creation of the file.

Thanks for your help. Just couple of questions so I can learn from this. Why does the stream name have to be passed by reference, and what does "using namespace std" do? Thanks for your help, again.

Thanks, i'm with you now.

or you could use

if(!InFile)
cout << "\nCould not open file.";

right?