int？ C (point? A, point? b)？ //what is returned is int? //change it to double.

{Double? sum，s 1，S2；

s 1 = ABS(a . x-b . x)；

S2 = ABS(a . y-b . y)；

sum = 2.0 *(s 1+S2)；

Return? Sum;

}

int？ C (double? R){// What is returned is int? //change it to double.

Return? (2.0 * pi * r)；

}

//Check the output again

c 1=C(a，b)；

C2 = C(r)；

cout & lt& ltc 1 & lt； & ltendl & lt& ltc2 & lt& ltendl////output the return values of c (a, b) and c (r).

//How can it not be cosmetic surgery? To get a double, change the return types of the above two functions.