Macro definition error in C?

Question

#define SOUND_SPEED 0.034;    
int rtt; //round trip time in microsecond
double distance;
distance = (double)(rtt*SOUND_SPEED)/2;

It complains erro

Answer 1

#define SOUND_SPEED 0.034;
                         ^

Do not use the trailing ;

Actually you should never terminate a macro with a ;:

PRE11-C. Do not conclude macro definitions with a semicolon https://www.securecoding.cert.org/confluence/display/seccode/PRE11-C.+Do+not+conclude+macro+definitions+with+a+semicolon