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==Declare a class with method==

<source lang="cpp">class ThreeDimension {
public:
int X;
int Y;
int Z;

int range(); // compute and return the range
};</source>

==Default values in member functions==

<source lang="cpp">#include <iostream>

class Rectangle
{
public:

Rectangle(int width, int height);
~Rectangle(){}
void display(int aWidth, int aHeight,
bool UseCurrentVals = false) const;
private:
int itsWidth;
int itsHeight;
};

Rectangle::Rectangle(int width, int height): itsWidth(width), itsHeight(height
) {}

void Rectangle::display(int width, int height, bool UseCurrentValue) const
{
int printWidth;
int printHeight;

if (UseCurrentValue == true)
{
printWidth = itsWidth;
printHeight = itsHeight;
}
else
{
printWidth = width;
printHeight = height;
}

for (int i = 0; i<printHeight; i++)
{
for (int j = 0; j< printWidth; j++)
{
std::cout << "*";
}
std::cout << "\n";
}
}

int main()
{
Rectangle theRect(30,5);
std::cout << "display(0,0,true)...\n";
theRect.display(0,0,true);
std::cout <<"display(40,2)...\n";
theRect.display(40,2);
return 0;
}</source>
<pre class=codeResult>display(0,0,true)...
******************************
******************************
******************************
******************************
******************************
display(40,2)...
****************************************
****************************************</pre>

==Implement class member function==

<source lang="cpp">#include <iostream>
using namespace std;

// Declare the ThreeDimension class.
class ThreeDimension {
public:
int X;
int Y;
int Z;

int range();
};

// Implement the range member function.
int ThreeDimension::range() {
return Z * Y;
}

int main() {
ThreeDimension aDimension;
ThreeDimension bDimension;

int range1, range2;

// Assign values to fields in aDimension.
aDimension.X = 7;
aDimension.Y = 16;
aDimension.Z = 21;

// Assign values to fields in bDimension.
bDimension.X = 2;
bDimension.Y = 14;
bDimension.Z = 12;

// Compute the ranges assuming a full tank of gas.
range1 = aDimension.range();
range2 = bDimension.range();

cout << range1 << "\n";

cout << range2;

return 0;
}</source>
<pre class=codeResult>336
168</pre>

==member function overloading.==

<source lang="cpp">#include <iostream>
#include <math.h>
#include <stdlib.h>
using namespace std;

class absolute_value {
public:
int number(int);
double number(double);
};

int absolute_value::number(int test_data)
{
int answer;
answer=abs(test_data);
return (answer);
}
double absolute_value::number(double test_data)
{
double answer;
answer=fabs(test_data);
return (answer);
}
main( )
{
absolute_value neg_number;
cout << "The absolute value is " << neg_number.number(-583) << endl;
cout << "The absolute value is " << neg_number.number(-583.1749) << endl;
return (0);
}</source>

==Overloading class member functions==

<source lang="cpp">#include <iostream>

class Rectangle
{
public:
Rectangle(int width, int height);
~Rectangle(){}

// overloaded class function display
void display() const;
void display(int aWidth, int aHeight) const;

private:
int itsWidth;
int itsHeight;
};

Rectangle::Rectangle(int width, int height)
{
itsWidth = width;
itsHeight = height;
}

void Rectangle::display() const
{
display( itsWidth, itsHeight);
}

void Rectangle::display(int width, int height) const
{
for (int i = 0; i<height; i++)
{
for (int j = 0; j< width; j++)
{
std::cout << "+";
}
std::cout << "\n";
}
}

int main()
{
Rectangle theRect(30,5);
std::cout << "display(): \n";
theRect.display();
std::cout << "\ndisplay(40,2): \n";
theRect.display(40,2);
return 0;
}</source>
<pre class=codeResult>display():
++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++
display(40,2):
++++++++++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++++++</pre>

==overloading functions in base and derived classes==

<source lang="cpp">#include <iostream>
using namespace std;
#include <process.h>)
class Stack{
protected:
enum { MAX = 3 };
int st[MAX];
int top;
public:
Stack()
{ top = -1; }
void push(int var)
{ st[++top] = var; }
int pop()
{ return st[top--]; }
};
class Stack2 : public Stack
{
public:
void push(int var)
{
if(top >= MAX-1)
{ cout << "\nError: stack is full"; exit(1); }
Stack::push(var);
}
int pop()
{
if(top < 0)
{ cout << "\nError: stack is empty\n"; exit(1); }
return Stack::pop();
}
};
int main()
{
Stack2 s1;

s1.push(11);
s1.push(22);
s1.push(33);

cout << endl << s1.pop();
cout << endl << s1.pop();
cout << endl << s1.pop();
cout << endl << s1.pop();
cout << endl;
return 0;
}</source>

==overloading two class member functions==

<source lang="cpp">#include <iostream>
#include <math.h>
#include <string>
using namespace std;
const double DEG_TO_RAD=0.0174532925;

class trigonometric {
double angle;
double answer_sine;
double answer_cosine;
double answer_tangent;
public:
void trig_calc(double);
void trig_calc(char *);
};
void trigonometric::trig_calc(double degrees)
{
angle=degrees;
answer_sine=sin(angle * DEG_TO_RAD);
answer_cosine=cos(angle * DEG_TO_RAD);
answer_tangent=tan(angle * DEG_TO_RAD);
cout << "\nFor an angle of " << angle << " degrees." << endl;
cout << "The sine is " << answer_sine << endl;
cout << "The cosine is " << answer_cosine << endl;
cout << "The tangent is " << answer_tangent << endl;
}

void trigonometric::trig_calc(char *dat)
{
char *deg,*min,*sec;
deg=strtok(dat,"d ");
min=strtok(0,"m ");
sec=strtok(0,"s");
angle=atof(deg)+((atof(min))/60.0)+((atof(sec))/360.0);
answer_sine=sin(angle * DEG_TO_RAD);
answer_cosine=cos(angle * DEG_TO_RAD);
answer_tangent=tan(angle * DEG_TO_RAD);
cout << "\nFor an angle of " << angle << " degrees." << endl;
cout << "The sine is " << answer_sine << endl;
cout << "The cosine is " << answer_cosine << endl;
cout << "The tangent is " << answer_tangent << endl;
}
main()
{
trigonometric data;
data.trig_calc(75.0);

char str1[] = "35d 75m 20s";
data.trig_calc(str1);

data.trig_calc(145.72);
char str2[] = "65d 45m 30s";
data.trig_calc(str2);

return (0);
}</source>

==The class member access operators . and ->==

<source lang="cpp">#include <iostream>
using std::cout;
using std::endl;
class MyClass
{
public:
void setX( int value )
{
x = value;
}
void print()
{
cout << x << endl;
}
private:
int x;
};
int main()
{
MyClass obj;
MyClass *objPtr = &obj;
MyClass &objRef = obj;
obj.setX( 1 );
obj.print();
objRef.setX( 2 );
objRef.print();
objPtr->setX( 3 );
objPtr->print();
return 0;
}</source>
<pre class=codeResult>1
2
3</pre>

==Use class as the member function parameter type==

<source lang="cpp">#include<iostream.h>
#include<iomanip.h>
class Rectangle
{
private:
float length;
float height;
public:
Rectangle(){}
Rectangle(float loge,float shge)
{
length=loge;
height=shge;
}
void getlength()
{
cout<<"Input large edge:";
cin>>length;
cout<<"Input small edge:";
cin>>height;
}
void showsquare()
{
cout<<setprecision(3) <<length*height<<endl;
}
void addsquare(Rectangle r1,Rectangle r2);
void addedge(Rectangle r1,Rectangle r2);
};
void Rectangle::addsquare(Rectangle r1,Rectangle r2)
{
length=r1.length+r2.length;
height=r1.height+r2.height;
cout<<"\n Total of Rectangle square:"
<<r1.length*r1.height+r2.length*r2.height;
}
void Rectangle::addedge(Rectangle r1,Rectangle r2)
{
length=r1.length+r2.length;
height=r1.height+r2.height;
cout<<"\n Toatal of Rectangle length:"
<<setprecision(3)<<(length+height)*2;
}
main()
{
Rectangle room1(15.5,6.5);
Rectangle room2,room3;
room2.getlength();
cout<<"Square of room1 Rectangle is:";
room1.showsquare();
cout<<"square of room2 Rectangle is:";
room2.showsquare();
room3.addsquare(room1,room2);
room3.addedge(room1,room2);
return 0;
}</source>
<pre class=codeResult>Input large edge:123
Input small edge:12
Square of room1 Rectangle is:101
square of room2 Rectangle is:1.48e+003
Total of Rectangle square:1.58e+003
Toatal of Rectangle length:314"</pre>

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