const reference
#include <iostream>
class MyType
{
public:
MyType();
MyType(int initialValue);
~MyType(){}
int GetItsVal()const { return itsVal; }
void SetItsVal(int x) {itsVal = x; }
MyType Add(const MyType &);
private:
int itsVal;
};
MyType::MyType(int initialValue): itsVal(initialValue) {}
MyType::MyType(): itsVal(0) {}
MyType MyType::Add(const MyType & rhs)
{
return MyType(itsVal+ rhs.GetItsVal());
}
int main()
{
MyType varOne(2), varTwo(4), varThree;
varThree = varOne.Add(varTwo);
std::cout << "varOne: " << varOne.GetItsVal()<< std::endl;
std::cout << "varTwo: " << varTwo.GetItsVal() << std::endl;
std::cout << "varThree: " << varThree.GetItsVal()
<< std::endl;
return 0;
}varOne: 2
varTwo: 4
varThree: 6
Use a const pointer parameter
#include <iostream>
using namespace std;
int f(const int *val);
int main()
{
int result;
int v = 10;
result = f(&v);
cout << v << " fd is " << result;
cout << "\n";
return 0;
}
int f(const int *val)
{
return - *val;
}10 fd is -10
