Help: Eof

[zeny]

Hi everybody,

My program reads user commands from the console until it finds an EOF. My question is: how does the program knows that an EOF has been inserted? And how does a user introduces an EOF as input through the console?

I´m using the method below to read the input:

static String readLn (int maxLg)
{
byte lin[] = new byte[maxLg];
int lg = 0, car = -1;
String line = "";
try
{
while (lg < maxLg)
{
car = System.in.read ();
if ((car < 0) || (car == '\n'))
break;
lin[lg++] += car;
}
}
catch (IOException e)
{
return (null);
}
if ((car < 0) && (lg == 0)){
return (null); // eof
}

return (new String (lin, 0, lg));
}

Thus, to read the input the program calls that method, readLn(). For example:
String input = readLn(1024).tr im();. From this example how do i know that the string "input" is an EOF? I´d be much thankful for any help.

Best Regards

[sicarie]

Hi everybody,

My program reads user commands from the console until it finds an EOF. My question is: how does the program knows that an EOF has been inserted? And how does a user introduces an EOF as input through the console?

I´m using the method below to read the input:

static String readLn (int maxLg)
{
byte lin[] = new byte[maxLg];
int lg = 0, car = -1;
String line = "";
try
{
while (lg < maxLg)
{
car = System.in.read ();
if ((car < 0) || (car == '\n'))
break;
lin[lg++] += car;
}
}
catch (IOException e)
{
return (null);
}
if ((car < 0) && (lg == 0)){
return (null); // eof
}

return (new String (lin, 0, lg));
}

Thus, to read the input the program calls that method, readLn(). For example:
String input = readLn(1024).tr im();. From this example how do i know that the string "input" is an EOF? I´d be much thankful for any help.

Best Regards

I'm pretty sure the concept is the same as C/C++ (please correct me if I'm wrong!), so that's what the rest of this post will be drawing from.

EOF is a sentinel value that is interpreted by a compiler. I know in GCC, last time I printed it out, it was -1 when assigned an int value - similar to how strings are terminated with '\0' (once again, certain types of strings - I believe C strings in this case). It's just a representation of some arbitrary, but known, value.

But that is why you can make the 'stream.eof()' call - you can insert that into a while loop (while !stream.eof()) and have it do all the work for you, and I have no idea how to input one from the keyboard, my recommendation would be

"Enter 'end' to end the program: "
and then do an
if (s_inputLine.eq ualsIgnoreCase( "end"))
System.exit()
structure.

[r035198x]

Yes

 
if (s_inputLine.equalsIgnoreCase("end")) 
System.exit(0)

Use that.

[sicarie]

Yes

 
if (s_inputLine.equalsIgnoreCase("end")) 
System.exit(0)

Use that.

r0-

I suppose I should be trying it (and will as soon as I finish this post), but will "end" work? I didn't know that was a Java keyword...

[r035198x]

r0-

I suppose I should be trying it (and will as soon as I finish this post), but will "end" work? I didn't know that was a Java keyword...

end is not a Java keyword. It does not matter in this case anyway because you are getting it as a String literal not using it as a variable