/in/foo.cc: In constructor 'BigInt::BigInt(int)':
/in/foo.cc:33:34: error: 'floor' was not declared in this scope
    nInteger = floor(nInteger / 10);
                                  ^
/in/foo.cc: In constructor 'BigInt::BigInt(char*)':
/in/foo.cc:67:33: error: 'strlen' was not declared in this scope
   int nLength = strlen(strBigInt);
                                 ^
/in/foo.cc: In member function 'BigInt BigInt::IntegerToBigInt(int)':
/in/foo.cc:335:34: error: 'floor' was not declared in this scope
    nInteger = floor(nInteger / 10);
                                  ^
/in/foo.cc: In static member function 'static BigInt BigInt::StringToBigInt(char*)':
/in/foo.cc:403:33: error: 'strlen' was not declared in this scope
   int nLength = strlen(strBigInt);
                                 ^