Victor Bazarov
9/24/2008 5:52:00 PM
bingo wrote:
> Hi, All:
> I'm really new to C++, so please forgive If I asked stupid
> questions:
>
> I was trying to use the following Vector class to do some
> calculations:
>
> =============================
> class Vector {
> public:
> double x,y,z;
>
> inline Vector(void) : x(-99999), y(-99999), z(-99999) { ; }
> // inline Vector(void) { ; }
>
> inline Vector( double newx, double newy, double newz)
> : x(newx), y(newy), z(newz) { ; }
>
> inline Vector( double newv ) // allow Vector v = 0; etc.
> : x(newv), y(newv), z(newv) { ; }
>
> inline Vector(const FloatVector &v) : x(v.x), y(v.y), z(v.z)
> { ; }
>
> inline double operator[](int i) {
> return i==0 ? x
> :i==1 ? y
> :i==2 ? z
> : x;
>
> }
>
> // v1 = v2
> inline Vector& operator=(const Vector &v2) {
> x = v2.x;
> y = v2.y;
> z = v2.z;
> return *this;
> }
>
> // v1 = const;
> inline Vector& operator=(const double &v2) {
> x = v2;
> y = v2;
> z = v2;
> return *this;
> }
>
> // addition of two vectors
> inline friend Vector operator+(const Vector& v1, const Vector&
> v2) {
> return Vector( v1.x+v2.x, v1.y+v2.y, v1.z+v2.z);
> }
>
> // negation
> inline friend Vector operator-(const Vector &v1) {
> return Vector( -v1.x, -v1.y, -v1.z);
> }
>
> // subtraction
> inline friend Vector operator-(const Vector &v1, const Vector
> &v2) {
> return Vector( v1.x-v2.x, v1.y-v2.y, v1.z-v2.z);
> }
>
> // inner ("dot") product
> inline friend double operator*(const Vector &v1, const Vector
> &v2) {
> return v1.x * v2.x + v1.y * v2.y + v1.z * v2.z;
> }
> // scalar product
> inline friend Vector operator*(const double &f, const Vector &v1)
> {
> return Vector(f*v1.x, f*v1.y, f*v1.z);
> }
> // scalar product
> inline friend Vector operator*(const Vector &v1, const double &f)
> {
> return Vector(f*v1.x, f*v1.y, f*v1.z);
> }
> // division by a scalar
> inline friend Vector operator/(const Vector &v1, const double &f)
> {
> return Vector(v1.x/f, v1.y/f, v1.z/f);
> }
>
> };
> =======================================
>
> and my main program looks like this:
>
> int main () {
>
> Vector a, b, c, d;
> a = b - c + d;
> a = b * 0.5;
> ......
> }
>
> Now my question is : for the operation - , + and scalar product, will
> it create a new Vector for return, and not be released in my
> calculation, which finally leads to memory leak? If so, how can I
> solve the problem?
No, there is no memory leak. The temporary object is created by the
language and disposed of at the end of its lifetime without your
explicit instruction. Don't worry about it.
V
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