The following two function prototypes have been created in the "library. h$"$ file. You are required to implement these two functions in the

"library.cpp$"$ file and call these functions in the main function.

double find $\_$rate$($string abbreviation$)$;

This function is to take the abbreviation of a currency and look up the "rates. txt$"$ file to return the corresponding exchange rate. The function shall return O if no matching currency is found.

Note that the "rates. txt$"$ file stores the exchange rates from US dollars to different foreign currencies.

void convert$($double foreign, double rate, double& dollars$)$;