Question

Does defining multiple variables on one line offer some form of optimization for the build process or is it simply a choice of coding style?

For example would this:

void foo()
{
    int a, b, c, d;

    ..... // do something with a,b,c and d
}

Offer any optimization over this:

void bar()
{
    int a;
    int b;
    int c;
    int d;

    ..... // do something with a,b,c and d
}

Answer 1

Possibly, yes. Smaller input files are faster to read for the compiler. But it would depend a lot on the implementation of the compiler. If you are interested in reducing build times in a compiler independent manner, there are a lot of other optimisations which can be done. Large-Scale C++ Software Design by John Lakos is a very good book to read for this.