Why do you not declare several variables of the same type on the same line?

Because in some languages, var2 and var3 in your example would not be strings, they would be variants (untyped).

To be honest I am not against it. I think that its perfectly feasible to group similar variables on the same line e.g.

float fMin, fMax;

however I steer clear when the variables are unrelated e.g.

int iBalance, iColor;

Here's my reasons:

• Readability, easier to spot if you know there's only one on each line
• Version control, less intra-line changes, more single-line additions, changes, or deletions, easier to merge from one branch to another