This should be done in C not C++.

Write a function (order_char) that orders the stored values of three characters. Suppose, for example, that c1, c2, and c3 are character variables having the values C, B, and D, respectively. Then the function call order_char(&c1, &c2, &c3) should cause the stored values of c1, c2, and c3 to be B, C, and D, respectively.