Debugging

Compile-time Errors

Since D is comprehensive language, you will probably run into error messages from the compiler. Within template code, those error messages can easily become nearly incomprehensible.

Run-time Errors

Run-time errors means that the compiled program does not behave like intended.

Printf Debugging

The easiest way to debug the code is insert print commands everywhere. From C this is called “printf debugging”, although it is “writeln debugging” in D.

There is the debug keyword together with the the -debug compiler switch. You can disable your print commands with this switch without deleting them. Consider the following code snippet.

writeln("Hello");
debug writeln("World");

If compiled without -debug, it will print only “Hello”. However, compiled with -debug, it will also print “World”.

Warning

Be careful not to put necessary code into debug, otherwise your release build might behave differently.

Logging

Unfortunately, there is no logging module in the standard library so far.

Debugger

The dmd compiler provides the -g switch, which enables you to use gdb or whatever debugger you like. The debugger should then know about names, variable values, etc.