(turn) c about inheritance get dizzy-CodePudding

Recently in the title of type c + +, always make mistakes about inheritance, before using the feeling is very good, some of the same code can pass some but not by very headache
Want to ask where there's a better interpretation of the
Such as this code calculates the distance to the origin: () is not in conformity with the result, only the output of the first input value

 # include 
#include 
using namespace std; 
The class point1d 
{
Protected: 
Float x; 
Public: 
Point1d (float a) 
{
X=a; 
} 
Float short () 
{
If (x<0) 
The return - x; 
The else 
return x; 
} 
}; 
The class point2d: public point1d 
{
Protected: 
Float y; 
Public: 
Point2d (float a, float b) : point1d (a) 
{
X=a; 
Y=b; 
} 
Float short () 
{
Float d=SQRT (x * * y x + y); 
Return d; 
} 
}; 
The class point3d: public point2d 
{
Protected: 
Float z; 
Public: 
Point3d (float a, float b, float c) : point2d (a, b) 
{
X=a; 
Y=b; 
Z=c; 
} 
Float short () 
{
Float d=SQRT (x * * y x + y + z * z); 
return d; 
} 
}; 
Int main () 
{
The int type. 
Cin> The type; 
Point1d * p; 
float a,b,c; 
While (type!=0) 
{
The switch (type) 
{
Case 1: 
Cin> a; 
P=new point1d (a); 
break; 
Case 2: 
Cin> a> b; 
P=new point2d (a, b); 
break; 
Case 3: 
Cin> a> b> c; 
P=new point3d (a, b, c); 
break; 
} 
CoutCin> The type; 
} 
}

There is more to the previous version:

 
#include 
#include 
using namespace std; 
The class point1d 
{
Protected: 
Float x; 
Public: 
Point1d float (p=0.0);//the line commented out via 
Float short () 
{
Cin> x; 
If (x<0) 
The return - x; 
The else 
return x; 
} 
}; 
Class point2d: public point1d//complains here 
{
Protected: 
Float y; 
Public: 
Float short () 
{
Cin> X> y; 
Float d=SQRT (x * * y x + y); 
return d; 
} 
}; 
The class point3d: public point2d 
{
Protected: 
Float z; 
Public: 
Float short () 
{
Cin> X> y> Z; 
Float d=SQRT (x * * y x + y + z * z); 
return d; 
} 
}; 
Int main () 
{
The int type. 
Cin> The type; 
While (type!=0) 
{
Point1d * p; 
Switch (type)//if this operation, the result is not in conformity with the 
{
Case 1: 
P=new point1d//if no this line will run this situation error 
Coutbreak; 
Case 2: 
P=new point2d; 
Cout
break; 
Case 3: 
P=new point3d; 
Cout
break; 
} 
} 
}

TAT is stunned

CodePudding user response:

Reduce the number of inheritance may be better

CodePudding user response:

You this is the wrong use of the inheritance

CodePudding user response:

refer to the second floor truth is right or wrong response:

you that this is the wrong use of inheritance

So just for help, didn't understand so wrong

CodePudding user response:

reference Sy_Faker reply: 3/f

Quote: refer to the second floor truth is right or wrong response:

You this is the wrong use of the inheritance

So just for help, didn't understand so wrong

Your first question, is the inheritance,
According to the magnitude of rule: any base class can appear, subclasses can appear,
Your base class is point1, you think about it, any point1 *, whether can be replaced with point2 and point3???????
Obviously can't,
The second problem is that the problem of c/c + + language,
Type pointer variable to point to specific address can be calculated,
So after p must be new to short ()

CodePudding user response:

Again again come, I knock a code error

 # include 
#include 
using namespace std; 
The class time 
{
Protected: 
Int second; 
Int minute; 
Int hour; 
Public: 
Void init () 
{
Int h, m, s; 
Cin> H> M> s; 
getchar(); 
Hour=h; 
Minute=m; 
Second=s; 
} 
Void operator + + () 
{
Second++; 
If (second==60) 
{
Second=0; 
Minute++; 
} 
If (minute==60) 
{
Minute=0; 
Hour++; 
} 
} 
Void operator, () 
{
Second,; 
If (second<0) 
{
Second=59; 
Minute -; 
} 
If (minute<0) 
{
Minute=59; 
Hour -; 
} 
} 
}; 
The class time_12hours: public time 
{
The string type. 
String interval; 
Public: 
Void the print () 
{
Cout} 
Void in (string STR) 
{
The interval=STR; 
} 
Void operator, () 
{
If (hour<0) 
Hour=12; 
} 
Void operator + + () 
{
If (hour==60) 
Hour=0; 
} 
}; 
The class time_24hours: public time 
{
The string type. 
Public: 
Void the print () 
{
Cout} 
Void operator + + () 
{
If (hour==60) 
Hour=0; 
} 
Void operator, () 
{
If (hour<0) 
Hour=23; nullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnull