C++ Read PGM file

Hello everyone,

I am attempting to read a PGM file on standard input and print out the number of rows and columns that exist. I know that the file format begins with P2 and the next lines in the file are 235, 185, 255, then the pixels etc. I need to read these values and print them out using printf. I could use some help as to how to read in the values. Thanks for any help I can get.

fstream won't work? IF you know what to expect I would read in untill you get to the dimensions and just save the dimensions and close the fstream.

Well, I will be running on it several different files from the command line. Example: ./a.out < something.pgm and somethingelse.pgm.
So I was thinking of fscanf or sscanf. Or if fstream will work could you post an example?

**EDIT:
I just wanted to mention I am new to c++. I have experience with java but not much in c or c++.

If your doing command line you can pass it as an arg... I would think at least.

Code:

#include <iostream>
#include <fstream>

using namespace std;

int main(int argc, char* argv[])
{
   ifstream infile;
   char *filepath;
   char var1[80];
   filepath = new char[strlen(argv[1])+1];
   strcpy(filepath,argv[1]);
   infile.open(filepath);
   infile>>var1;   //loop this to read next chunk of data
   return 0;

}

I don't know the PGM layout, but you can use this general code to read from a file. Whitespace will break the read by the way so we don't always grab 80 chars of data just seperate chunks this might help some.

Actually, I figured out how I wanted to read in the file. I just used a while loop and getline and stored the information in a string. How can I take the first few lines from my input and print them out?

just cout<<varname