How to set the include path an environment variables of g++

[eqq2002]

Hi:
Recently I was very interested in console model to compile some simple examples of c++, Unfortunately,I failed to do so.
My operation system is winxp, and I had installed DevCPP 4 inside. I also set path = "c:\dev-c++\bin", but it seemed to be hard to determine where and what I could set my "Include" and "lib".
For example:A simple piece of my code #include <iostream.h> doesn't work, the error raised by g++ is "can't find iostream.h"
PLS Help me ; a begginer of c++.
I've searched my question in this forum,but no suitble answer.Google don't work as well as your country in my homeland.

[RRick]

In unix, the PATH variable is good for finding programs (like your compiler). For the include and lib paths, you have to tell the compiler directly. For includes, add a -I (big i) in front of each include directory. For libraries, the simpliest way is to add -l (small l) before the complete path and library name. For example:

g++ -I. -I../include -l../lib/libstuff.a ... blah blah blah ...

Its also smart to turn on the compiler warnings (-Wall) and the debugger (-g -O0). Try 'man g++' to get more options, but watch out, there are a lot of them.

[eqq2002]

RRick:
Thank for your reply. "g++ -i" really help.
For std lib, Is there easy way such as Java's lib and include to set the path?

[RRick]

For the C++ and system libraries, the compiler knows where they are and takes care of the include and library path information.

You only need to add include paths for header files that aren't the C++ header files. Some of the sytem libraries need to be explicitly defined. Some are:

• -lm // math library
• -lpthread // Thread library

Your own and 3rd party libraries are bit more involved and take a -L (big L) path parameter. All libraries have the form lib<name>.a for a static library. For -lm the compiler looks for libm.a.

[Dillon02003]

In unix, the PATH variable is good for finding programs (like your compiler). For the include and lib paths, you have to tell the compiler directly. For includes, add a -I (big i) in front of each include directory. For libraries, the simpliest way is to add -l (small l) before the complete path and library name. For example:

g++ -I. -I../include -l../lib/libstuff.a ... blah blah blah ...

Its also smart to turn on the compiler warnings (-Wall) and the debugger (-g -O0). Try 'man g++' to get more options, but watch out, there are a lot of them.

How exactly do I go about doing that? I have the exact same problem as the guy who started this thread.

[kiseitai2]

If you are using an IDE such as Dev-CPP, there shouldn't be any error finding standard headers when you include. If there is a search issue you can add the path in the compiler options within the IDE. Also, know that a modern IDE usually takes care of the cmpiler parameter business for you, so you only need to tell the IDE where to find your lib and include folders. In fact, the IDE makes a full make file for you with all necessary variables / compiler parameters! Also, check your syntax, for not all header files in the std library set requires .h. Example, #include <iostream.h> would in fact be #include <iostream>. I had Dev-CPP before Code::Blocks and I used to have that problem, since some headers do need the .h. Try my correction and report back! That should be my mole of Si (a chemist will get this)! :)