The meaning is same for both c and c++.
++i means pre-increment and
i++ means post-increment
For better understanding see the example.
int x, y;
int i = 0;
x = ++i; // here pre-increment the value of i and then store it into x i.e (x = 1)
y = i++; // here post-increment the value of i after storing it into y, i.e (y = 1)
// to verify the above
printf("x = %d and y = %d\n", x, y);
x = 1 and y = 1