I'm writing a small C program to post process a huge txt file produced by a CFD software.

The CFD creates a "from.txt" file, in which every line contains many parameters calculated by it.
I need to copy the lines that contain the information i need to another "to.txt" files.

The problem is that I donīt know how to go thru the lines of the from.txt.
Once i know how to go thru them it wouldn't be that hard to write the rest of the program.

I working on something like...

while(c == getchar());
if (c == \n);

... but i have no idea how to go on...

I`m a newbie in this world... hope learn a lot from you all!