ANONYMOUS wrote: When formatting output with printf() and friends, there really is no difference. However when scanning/parsing input with scanf() and friends, using "%i" supports reading in integers in different numeric bases, such as base-10 (decimal), base-8 (octal) and base-16 (hexadecimal). I prefer (try) to keep my use of "%i" consistent when using either printf() or scanf(), so try to always use "%i". And, while (I believe) "%d" is derived from the word 'decimal', my brain associates 'decimal' with 'decimal-point' and floating-point values, and not with a base-10 integer. So, again, I prefer "%i" with which I simply associate 'integer'.