Stock
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//Stock.h #ifndef__STOCK_H__ #define__STOCK_H__ Const int NAME_SIZE=20; Class Stock { Public: Stock(char* szName, double dValue, int nNum); void Buy(int nAdd); double Sell(int nSold); Private: char* n_szName; char m_szName[NAME_SIZE+1]; double m_dPrice; int m_nNumber Public: void SetPrice(double dPrice); const double GetPrice()const; }; #endif OR Class Stock { Public: Stock(char* szName, double dValue, int nNum); ~stock(): //to clean up memory void Buy(int nAdd); double Sell(int nSold); Private: char* n_szName; double m_dPrice; int m_nNumber Public: void SetPrice(double dPrice); const double GetPrice()const; }; #endif |
//Stock.cpp #include "Stock.h" Stock::stock(char*, szName, double dValue, int nNum) { m_nNumber=nNum; m_dPrice = dValue; strncpy(m_szName, szName, NAME_SIZE); m_szName[NAME_SIZE]= ‘\0’; } -don’t need to assign memory -don’t need a destructor, compiler will give you one which is adequate OR Stock::stock(char*, szName, double dValue, int nNum) { m_nNumber=nNum; m_dPrice = dValue; m_szName = new char [strlen(szName) +1]; strcpy(m_szName,szName); } Stock::~Stock() //to clean up memory, deconstructor { delete[] m_szName; } |
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<Accessor Functions> void Stock::SetPrice(double dPrice) { m_dPrice=dPrice; }
const double stock::GetPrice() const { return n_dPrice; } |
<Accessor Functions> void Stock::Buy(int nAdd) { m_nNumber += nAdd; }
double stock::Sell(int nSold) { assert(nSold <= m_nNumber); double dValue = n_dPrice * nSold; m_nNumber -= nSold; return dValue; } |
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#inlcude "stock.h" int main() { Stock s("microsloth", 91.385,100); s.Add(100; double dCash = s.Sell(150);
(version using only SetPrice) int main() { Stock s("microsloth", 91.385,100); s.SetPrice(100.5); if(sGetPrice()==100.5) { cout<<"C++Rocks!" << endl; } else { cout<<"VB Drools" <<endl; } |
Rules: -use new-> delete in c++ -you can use malloc->freem but why? -if you use malloc, don’t use delete -if you use new,, don’t use free Constructors (ctor) -can take arguments return no vlaue – not even null/void -they can be explicitly or implictly called -used for dat initialization -method name: same as the class Destructors (dtor) -take no arguments -return no values, not even void -used for data cleanup -method name: tilde followed by the name of the name of the class (~stock() ) -always called implicity -if you don’t write one, the compiler will supply a "do nothing" dtor for you. –but, will not "delete" your memory. |
