Thread: Searching a .txt file?

Hi, I was wondering how I could search a .txt file for a certain string. What I mean is this, if I have a string:

Code:

string somestring="three";

and I I have a .txt file that contains the following:

Code:

one
two
three

the program would search the file and compare each line. It would be like this: if somestring equals first line, say "somestring is in the .txt file!", else go to the next line. If somestring equals the second line....etc. Does anyone know how to do this? In other words, I want to know if a string is in a .txt file or not. Thanks in advance!