Thread: file pointer as an argument?

hello,

When we pass int pointer or char to a function, we do something like this:

main()
{
pass(&i,&c);
}

void pass(int *i, char *c)
{
.........................
}

Question:
How do I pass a file pointer that is opened in the main function to another function as an argument? After passing the file pointer to the function, do I need to close the file i.e fclose(fp) at the end of that function, eventhough, there is fclose(fp) in the main function?

Please help!

FILE*fp = fopen("myfile.txt","r");
myfunction( fp );


where:

void myfunction( FILE* fp )
{
... do stuff here...
}



Quzah.

You should be able to close the file from your main() function or your other function, I don't think it really matters WHERE you close it, as long as you make sure it gets closed...

(:

Additionally, if you try and close a file that has been closed, you may end up with fun errors / unexpected results.

I use this rule of thumb: Close the file where you open it.

Exceptions to this would be if you were trying for OO design and had open and close methods.

Quzah.

Let me clarify that: Close the file in the same block / function you open it in. That is to say:

Code:

void myfun( FILE* fp )
{
   fclose( fp ); //bad, IMO
}

void myfun2( char *s )
{
   FILE*fp=fopen( s, "r" );
   //do stuff here
   fclose( fp );
}

int main( void )
{
   FILE*fp=NULL;
   fp = fopen( SomeFileHere, "r" );
   //do stuff here

   myfun( fp ); //bad, IMO

   myfun2( "SomeFile" ); //good IMO

   fclose( fp ); //good, IMO
}

Quzah.