ifstream not reading next line?

[aseminov]

Hello all,

I have a file blah.txt like this:

3 1 4
1 2 3

and here is my code to read in that file:

int x = 0, y = 0, z = 0;
ifstream data("blah.txt");
while(x != 1)
{
    data >> x >> y >> z;
}

For some reason, it just keeps readin in the values: 3 1 4

What am I doing incorrectly?

Thanks!!

[ZuK]

First of all you should check for a successfu read.
Seems that reading fails and that's why you get an infinite loop.
try something like this

int x = 0, y = 0, z = 0;
ifstream data("blah.txt");
while( data >> x >> y >> z)
{
   if ( x == 1 ) 
       break;
}

Kurt

[aseminov]

Ok I see what you mean... obviously my "data >> x >> y >> z" is failing. How do I debug why it failed?

Thanks.

[ZuK]

I'd add some output statements
e.g.

int x = 0, y = 0, z = 0;
ifstream data("blah.txt");
while( data >> x >> y >> z)
{
   std::cout << "x:" << x << " y:" << y << " z:" << z << std::endl;
   if ( x == 1 ) 
       break;
}
std::cout << "after loop x:" << x << " y:" << y << " z:" << z << std::endl;

if that doesnt give you any clue then I would check "blah.txt"
Kurt

[cconn64]

Hello all,

I have a file blah.txt like this:

3 1 4
1 2 3

and here is my code to read in that file:

int x = 0, y = 0, z = 0;
ifstream data("blah.txt");
while(x != 1)
{
    data >> x >> y >> z;
}

For some reason, it just keeps readin in the values: 3 1 4

What am I doing incorrectly?

Thanks!!

It is the way streams operate. You never read the EOL.
Try adding this to your code:

data >> x >> y >> z;   // Read the values from the file for each line
data.ignore(512, '\n');   // skip past the EOL

[ZuK]

It is the way streams operate. You never read the EOL.

Not true. '\n' is whitspace and the streamextractor for an int skips leading whitspaces by default.
Kurt