Understanding Error Messages

In the days of FORTRAN code, the error messages generated by the compiler, the linker and during execution were generally not too difficult to understand. With the much richer C++ syntax, auto-generated class dictionary code, shared libraries and dynamic linking, it can be very hard to decipher some error messages. The purpose of this section is to collect together the common problems that people encounter. So if you hit a problem, take a look here.

Errors are classified according to what you were doing when the problem occurred:-

Errors while Compiling i.e. when invoking the C++ compiler.
It does not include errors reported during execution by CINT.
Warnings while Compiling i.e. addition warning messages generated by the compiler,
that do not inhibit further code building but indicate potential problems.
Linking i.e. when linking to build an executable.
Program Start i.e. When starting to run a program.
Running i.e. during execution. It includes errors reported by CINT.
Linux System Errors i.e. errors reported by Linux.

Other useful sources of information about errors are:-

Search the ROOT Web Site This can search Roottalk that is a discussion forum that includes many mails from users asking about problems.
MINOS HyperNews Forums: OO Software discussion This is a place where we plan to include discussions about problems with MINOS software.

If all else fails. If things just don't work and you don't know why, try the following in this order,and after each step, see if the problem is fixed.:-

Log out and in again. This will clean up your environment.
If you have a Test Release
1. ```
  cvs update
  gmake
```
  This will help if the interfaces have changed in the Base Release.
2. ```
  gmake clean
  gmake
```
  In case SRT missed some dependency and failed to rebuild something it should have done.

Let me know if you get stuck on a problem not covered here - we may at least spare someone else the pain!

Contact: Nick West (n.west1@physics.oxford.ac.uk>)