C++读书笔记之 关系运算符重载 大于号; 小于号< 等于号== 重载 overload
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public:
static const double absError=0.0000001;
static bool IsEqual(double a, double b)
if (a==b)
return true;
if (fabs(a-b)<absError)
return true;
return false;
/**重载赋值运算符后 交换两个类的数据**/
void swap(Distance& d)Distance temp;
temp=*this;
*this=d;
d=temp;
/*** overloaded < operator 重载小于号 ***/
bool operator <(const Distance& d)
if((feet - d.feet<absError)||(feet == d.feet && inches - d.inches<absError))
return true;
return false;
/*** overloaded > operator 重载大于号***/
bool operator > (const Distance& d)
if((feet -d.feet>absError)||(feet == d.feet && inches - d.inches>absError))
return true;
return false;
/*** overloaded == operator 重载等于号 ***/
bool operator ==(const Distance& d)
if(IsEqual(feet,d.feet) && IsEqual(inches,d.inches))
return true;
return false;
#include <iostream>
#include <math.h>
using namespace std;
class Distance
private:
double feet; // 0 to infinite
double inches;
public:
static const double absError=0.0000001;
static bool IsEqual(double a, double b)
if (a==b)
return true;
if (fabs(a-b)<absError)
return true;
return false;
// required constructors
Distance()
feet = 0;
inches = 0;
Distance(double f, double i)
feet = f;
inches = i;
/**重新设置数据**/
void set(double f, double i)
feet = f;
inches = i;
/**重载赋值运算符后 交换两个类的数据**/
void swap(Distance& d)
Distance temp;
temp=*this;
*this=d;
d=temp;
// method to display distance
void displayDistance()
cout <<" Feet: " << feet << " Inches:" << inches <<endl;
/*** overloaded minus (-) operator ***/
Distance operator- ()
feet = -feet;
inches = -inches;
return Distance(feet, inches);
/*** overloaded < operator 重载小于号 ***/
bool operator <(const Distance& d)
if((feet - d.feet<absError)||(feet == d.feet && inches - d.inches<absError))
return true;
return false;
/*** overloaded > operator 重载大于号***/
bool operator > (const Distance& d)
if((feet -d.feet>absError)||(feet == d.feet && inches - d.inches>absError))
return true;
return false;
/*** overloaded == operator 重载等于号 ***/
bool operator ==(const Distance& d)
if(IsEqual(feet,d.feet) && IsEqual(inches,d.inches))
return true;
return false;
;
int main()
Distance D1(20.08,5.12 ), D2(20.13, 4.20);
cout<<"before swap :\\n";
cout<<"D1:----> ";
D1.displayDistance();
cout<<"D2:----> ";
D2.displayDistance();
if( D1 < D2 )
cout << "D1 is less than D2 " << endl;
else
cout << "D2 is less than D1 " << endl;
D1.swap(D2);
cout<<"after swap :\\n";
cout<<"D1:----> ";
D1.displayDistance();
cout<<"D2:----> ";
D2.displayDistance();
if( D1 < D2 )
cout << "D1 is less than D2 " << endl;
else
cout << "D2 is less than D1 " << endl;
double a=0.33,b=0.33;
cout<<"\\ndouble a=0.33,b=0.33 then Distance::IsEquall(a,b) = "
<<Distance::IsEqual(a,b)<<endl;
cout<<"after set(199.1,11.05)\\n";
D1.set(199.1,11.05);
D2.set(199.1,11.05);
D1.displayDistance();
D2.displayDistance();
if(D1==D2)
cout<<"\\n D1 equal D2 \\n";
return 0;
/**************************
运行结果：
before swap :
D1:----> Feet: 20.08 Inches:5.12
D2:----> Feet: 20.13 Inches:4.2
D1 is less than D2
after swap :
D1:----> Feet: 20.13 Inches:4.2
D2:----> Feet: 20.08 Inches:5.12
D2 is less than D1
double a=0.33,b=0.33 then Distance::IsEquall(a,b) = 1
after set(199.1,11.05)
Feet: 199.1 Inches:11.05
Feet: 199.1 Inches:11.05
D1 equal D2
Process returned 0 (0x0) execution time : 0.894 s
Press any key to continue.
****************************/
运行结果：
before swap :
D1:----> Feet: 20.08 Inches:5.12
D2:----> Feet: 20.13 Inches:4.2
D1 is less than D2
after swap :
D1:----> Feet: 20.13 Inches:4.2
D2:----> Feet: 20.08 Inches:5.12
D2 is less than D1
double a=0.33,b=0.33 then Distance::IsEquall(a,b) = 1
after set(199.1,11.05)
Feet: 199.1 Inches:11.05
Feet: 199.1 Inches:11.05
D1 equal D2
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