Uses of C comma operator [duplicate]

Answer 1

For me the one really useful case with commas in C is using them to perform something conditionally.

  if (something) dothis(), dothat(), x++;

this is equivalent to

  if (something) { dothis(); dothat(); x++; }

This is not about "typing less", it's just looks very clear sometimes.

Also loops are just like that:

while(true) x++, y += 5;

Of course both can only be useful when the conditional part or executable part of the loop is quite small, two-three operations.