- Class definition contains
necessary information
to
create
and
use
variables and methods of that class
- Class definition must include:
- member variables
- Name
- Type
- Relative offset (derived from the order of the variables)
- member methods
- Name
- Return Type
- Parameters
- Relative offset (derived from the order of the methods)
- member variables
- Example:
class Matrix3x3 { private: double A[3][3]; public: Vector3 operator* ( Vector3 & v ); // The implementation is elsewhere !! }; - Notice:
The body of the member function is not considered as part of the class definition
- The
implementation
of a
member function
can be specified in these places:
- inside the
class definition
(An inline function)
- outside the
class definition
This option permit the use of:
- header files to contain class definitions
- C program files to contain member function implementations
- inside the
class definition
- We will make 2 separate classes:
- Vector3
- Matrix3x3
- Vector3 provides
- Data for the vector
- Constructor() and Constructor(a,b,c)
- Vector3 * Matrix3x3 operation
- cout << Vector3 operation
- Matrix3x3 provides
- Data for the matrix
- Constructor() and Constructor(a,b,c,e,f,g,h,i)
- Matrix3x3 * Vector3 operation
- cout << Matrix3x3 operation
- Class definition
for Vector3
Vector3.h #include <iostream.h> class Matrix3x3; class Vector3 { private: double x[3]; public: Vector3(); Vector3(double a, double b, double c); Matrix3x3 operator*(Matrix3x3 & M); friend ostream & operator<<(ostream &, Vector3 &); friend class Matrix3x3; };
- Class definition
for Matrix3x3
Matrix3x3.h #include <iostream.h> class Vector3; class Matrix3x3 { private: double A[3][3]; public: Matrix3x3(); Matrix3x3(double a, double b, double c, double d, double e, double f, double g, double h, double i ); Vector3 operator*(Vector3 & v); friend ostream & operator<<(ostream &, Matrix3x3 &); friend class Vector3; };
- Class implementation
for Vector3
Vector3.C #include <iostream.h> #include "Matrix3x3.h" #include "Vector3.h" // constructor() Vector3::Vector3() { x[0] = 0; x[1] = 0; x[2] = 0; } // constructor(a,b,c) Vector3::Vector3(double a, double b, double c) { x[0] = a; x[1] = b; x[2] = c; } // Vector3 * Matrix3x3 operator Matrix3x3 Vector3::operator*(Matrix3x3 & X) { Matrix3x3 Z; int i, j; for (j = 0; j < 3; j = j + 1) for (i = 0; i < 3; i = i + 1) Z.A[i][j] = x[j] * X.A[i][j]; return Z; } // Output operator ostream & operator<<(ostream & cout, Vector3 & v) { int i; for (i = 0; i < 3; i=i+1) cout << v.x[i] << "\t"; cout << endl; return(cout); }
- Class implementation
for Matrix3x3
Matrix3x3.h #include <iostream.h> #include "Vector3.h" #include "Matrix3x3.h" // constructor() Matrix3x3::Matrix3x3() { int i, j; for (i = 0; i < 3; i = i + 1) for (j = 0; j < 3; j = j + 1) A[i][j] = 0; } // constructor(a,b,c,d,e,f,g,h,i) Matrix3x3::Matrix3x3(double a, double b, double c, double d, double e, double f, double g, double h, double i ) { A[0][0] = a; A[0][1] = b; A[0][2] = c; A[1][0] = d; A[1][1] = e; A[1][2] = f; A[2][0] = g; A[2][1] = h; A[2][2] = i; } // Matrix3x3 * Vector3 operator Vector3 Matrix3x3::operator*(Vector3 & v) { Vector3 z; int i, j; for (i = 0; i < 3; i=i+1) z.x[i] = 0; for (i = 0; i < 3; i=i+1) for (j = 0; j < 3; j=j+1) z.x[i] = z.x[i] + A[i][j]*v.x[j]; return z; } // Output operator ostream & operator<<(ostream & cout, Matrix3x3 & M) { int i, j; for (i = 0; i < 3; i=i+1) { for (j = 0; j < 3; j=j+1) cout << M.A[i][j] << "\t"; cout << endl; } return(cout); }
- Example program
using Matrix3x3
and Vector3
main.C #include
#include "Vector3.h" #include "Matrix3x3.h" int main(int argc, char *argv[]) { Matrix3x3 M1(1,1,1,1,1,1,1,1,1), M2(1,0,0,1,1,0,1,1,1); Vector3 v1(1,2,3), v2; // Matrix-vector multiply v2 = M1 * v1; M2 = v1 * M1; // Output operations cout << "Matrix M1:" << endl << M1 << endl; cout << "Vector v1:" << endl << v1 << endl; }
- Example Program:
(Demo above code)
- Vector3.h header file: click here
- Matrix3x3.h header file: click here
- Vector3.C implementation file: click here
- Matrix3x3.C implementation file: click here
- main.C program file: click here
Compile with:
CC main.C Vector3.C Matrix3x3.C
(Or use separate compilation).