Software Quality

When developing software, here's a partial list of things I value:

Build using multiple compilers

Sometimes you forget to #include something from a standard library that works on one compiler but doesn't on another or use constructs that don't compile on all compilers.

Static Analysis and high warning levels

I regularly run PVS-Studio, CppCheck and Clang static analyzers and use very high warning levels on my compilers.

My GCC warnings: -Wall -pedantic -Wextra -Wcast-align -Wcast-qual -Wctor-dtor-privacy -Wdisabled-optimization \
 -Wdouble-promotion -Wformat=2 -Winit-self -Winvalid-pch -Wlogical-op -Wmissing-include-dirs \
 -Wshadow -Wredundant-decls -Wsign-promo -Wstrict-null-sentinel -Wstrict-overflow=5 -Wtrampolines \
 -Wunsafe-loop-optimizations -Wvector-operation-performance -Wzero-as-null-pointer-constant

Unit Tests

I have found many bugs using them. Excellent for math stuff, serialization testing, error handling testing etc.
 

Test graphics code on multiple GPUs

Some drivers accept bad syntax in shaders or have bugs. I test my graphics code on NVIDIA, AMD and Intel GPUs on Windows, OS X and on Linux.

Minimize variable scope

Declare variables as close as possible to their use site and try to make them const. Ternary operator and lambdas can help here.
 

Avoid Boolean arguments

They make the code hard to read and often break the Single Responsibility Principle.

Avoid magic numbers

Same as above.

Collect metrics

Use tools like Metrix++ to get metrics like line count, cyclomatic complexity etc.

Extract complex conditionals into descriptive variables and methods.

Look out for Code Smells

Comment things that can't be expressed in code

First try to name your variables/methods so the comments are unnecessary. Only after that write comments.