When your programs contain mistakes, compiling them in the shell can result in large numbers of error messages scrolling by faster than you can read them. For this reason, I find it best to compile from within the emacs editor.

Example 1: Try This:

1. Get into emacs and call up one of the “hello” programs from the prior section. Change it so that it contains one or more syntax errors, and save this file.

2. Now give the emacs command: M-x compile. At the bottom of the screen, you will be asked for the compile command. If the suggested command is not what you want (it won’t be, until you learn to use make to manage your program compilations), then type in the proper command just as if you were typing it into the shell.

   emacs will invoke the compiler, showing its output in a window. Figure 1 shows a typical emacs session after such a compilation.

3. In this case, there should be one or more error messages. The emacs next-error command (C-x` ) will move you to the source code location of the first error. Each subsequent use of C-x ` will move you to the next error location in turn, until all the reported error messages have been dealt with.

   Use this command to step through the errors. (Note carefully that the second character in the C-x ` command is the “backwards” apostrophe, not the regular one.)

Figure 1: Compiling a program in emacs, with syntax errors

vim (“vi improved”) is an reasonable alternative to emacs on many Unix systems. It provides syntax-highlighting editor, can launch the compiler and will display the error messages, synchronized with the source code (here). It provides no interface to the debugger, however.

Figure 2: Compiling in vim

To learn the basics of running vim, give the command vimtutor.