i++;
simply mean
i=i+1;
i++; will just increament value of i by 1.
in c,or c++
i++,++i are same if. if they are not used with other variable.
in the same way --i,i-- are same.
consider
i=5;
i++;
now the value of i is simply 6;
i=5
++i;
again value of i is 6;
but u just consider statement
i=5;
c=i++;
the value of c is 5, i is 6.
i=5;
c=++i;
the value of c is 6,i is 6;