this is wat i have,
how can i get the val of the first array that i insert out.
thx
TOm
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include "vector"
using namespace std;
struct vertex
{
float pt[3];
};
void main(int argc, char ** argv)
{
vertex v;
std::vector<vertex> myVec;
v.pt[0] = 3;
v.pt[1] = 3;
v.pt[2] = 3;
myVec.push_back(v);
float temp[3];
temp = myVec.end()
cout << "front : " << temp[0];
}
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void main(int argc, char ** argv)
{
vertex v;
std::vector<vertex> myVec;
v.pt[0] = 3;
v.pt[1] = 3;
v.pt[2] = 3;
myVec.push_back(v);
vertex temp;
temp = myVec.front();
cout << "front : " << temp[0];
}
--------------------Config
Compiling...
array.cpp
C:\array.cpp(29) : error C2676: binary '[' : 'struct vertex' does not define this operator or a conversion to a type acceptable to the predefined operator
Error executing cl.exe.
array.obj - 1 error(s), 0 warning(s)
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include "vector"
using namespace std;
struct vertex
{
float pt[3];
};
void main(int argc, char ** argv)
{
std::vector<vertex> myVec;
vertex v;
v.pt[0] = 3;
v.pt[1] = 3;
v.pt[2] = 3;
myVec.push_back(v);
vertex temp; // missed the ';'
temp = myVec.back();
cout << "front : " << temp.pt[0];
}
compile just fine here...
As I wrote, 'temp[0];' should be 'temp.pt[0];'
Hi tom_mk,
Little correction. temp[0] in incorrect because temp is not an array but a structure. I think you meant temp.pt[0]
Correct the above and it will run perfectly fine.
One important suggestion. 'void main()' is wrong as the standard specifies that main returns an int. Returning anything from main invokes undefined behaviour which can result in anything.
Since main returns an int, insert a 'return 0;' just before the closing brace. The final program will be something like this.
#include <iostream>
#include <vector>
using namespace std;
struct vertex
{
float pt[3];
};
int main(int argc, char ** argv)
{
vertex v;
std::vector<vertex> myVec;
v.pt[0] = 3;
v.pt[1] = 3;
v.pt[2] = 3;
myVec.push_back(v);
vertex temp;
temp = myVec.front();
cout << "front : " << temp.pt[0];
return 0;
}
Cheers!
BTW, for further reference, you might want to check out http://cplus.about.com/lib
this is wat i doing
is this the right approach?
struct obj
{
float pt[3];
float col[3];
};
obj myObj;
obj myT;
std::vector<obj> myvec;
void myVertex(float x, float y, float z)
{
// myv
// myvtemp
myObj.pt[0] = x;
myObj.pt[1] = y;
myObj.pt[2] = z;
// v.push_back(i);
myvec.push_back(myObj);
}
void myColor(float r, float g, float b)
{
myObj.col[0] = r;
myObj.col[1] = g;
myObj.col[2] = b;
myvec.push_back(myObj);
}
Oh, OK, that's different and will work. What you could do is
struct obj {
enum type { POINT, COL};
type objType;
union
{
float pt[3];
float col[3];
}
};
void myVertex(float x, float y, float z)
{
// myv
obj MyObj;
myObj.pt[0] = x;
myObj.pt[1] = y;
myObj.pt[2] = z;
myObj.type = obj::POINT;
// v.push_back(i);
myvec.push_back(myObj);
}
void myColor(float r, float g, float b)
{
obj MyObj;
myObj.col[0] = r;
myObj.col[1] = g;
myObj.col[2] = b;
myObj.type = obj::COL;
myvec.push_back(myObj);
}
and evaluate obj::type when processing these structs.
void myVertex(float x, float y, float z)
{
obj myObj;
myObj.pt[0] = x;
myObj.pt[1] = y;
myObj.pt[2] = z;
myObj.type = obj::POINT;
myvec.push_back(myObj);
}
void myColor(float r, float g, float b)
{
obj myObj;
myObj.col[0] = r;
myObj.col[1] = g;
myObj.col[2] = b;
myObj.type = obj::COL;
myvec.push_back(myObj);
}
--------------------Config
Compiling...
mygl.cpp
C:\Documents and Settings\tooa\Desktop\cour
C:\Documents and Settings\tooa\Desktop\cour
C:\Documents and Settings\tooa\Desktop\cour
C:\Documents and Settings\tooa\Desktop\cour
Error executing cl.exe.
mygl.obj - 3 error(s), 0 warning(s)
my prior post has s.t incorrect
this is the correct one
void myVertex(float x, float y, float z)
{
obj myObj;
myObj.pt[0] = x;
myObj.pt[1] = y;
myObj.pt[2] = z;
myObj.type = obj::PT; // <--- problem
myvec.push_back(myObj);
}
//////////////////////////
// FUNC: myColor(r,g,b)
//////////////////////////
void myColor(float r, float g, float b)
{
obj myObj;
myObj.col[0] = r;
myObj.col[1] = g;
myObj.col[2] = b;
myObj.type = obj::COL; // <---- PROB
myvec.push_back(myObj);
}
--------------------Config
Compiling...
mygl.cpp
C:\Documents and Settings\tooa\Desktop\cour
C:\Documents and Settings\tooa\Desktop\cour
Error executing cl.exe.
mygl.obj - 2 error(s), 0 warning(s)
Sorry, my fault again (case and...), the following compiles fine:
struct obj {
enum type { POINT, COL};
type objtype;
union
{
float pt[3];
float col[3];
};
};
vector<obj> myvec;
void myVertex(float x, float y, float z)
{
obj myObj;
myObj.pt[0] = x;
myObj.pt[1] = y;
myObj.pt[2] = z;
myObj.objtype = obj::POINT;
myvec.push_back(myObj);
}
void myColor(float r, float g, float b)
{
obj myObj;
myObj.col[0] = r;
myObj.col[1] = g;
myObj.col[2] = b;
myObj.objtype = obj::COL;
myvec.push_back(myObj);
}
>> my prior post has s.t incorrect
OK, according to that it should be
struct obj {
enum type { POINT, COL};
type objtype;
union
{
float pt[3];
float col[3];
};
};
vector<obj> myvec; // this one needs to be declared somewhere
void myVertex(float x, float y, float z)
{
obj myObj;
myObj.pt[0] = x;
myObj.pt[1] = y;
myObj.pt[2] = z;
myObj.objtype = obj::PT; // <--- problem
myvec.push_back(myObj);
}
//////////////////////////
// FUNC: myColor(r,g,b)
//////////////////////////
void myColor(float r, float g, float b)
{
obj myObj;
myObj.col[0] = r;
myObj.col[1] = g;
myObj.col[2] = b;
myObj.objtype = obj::COL; // <---- PROB
myvec.push_back(myObj);
}
I made a different approach using derived classes:
#include <iostream>
#include <vector>
using namespace std;
class Obj
{
public:
Obj() {}
virtual ~Obj() { }
virtual bool isPoint() { return false; }
virtual bool isColor() { return false; }
virtual ostream& print(ostream& os) const { return os; }
friend ostream& operator << (ostream& os, const Obj& ob)
{
return ob.print(os);
}
};
class PtObj : public Obj
{
float pt[3];
public:
PtObj(float x, float y, float z) { pt[0] = x; pt[1] = y; pt[2] = z; }
virtual bool isPoint() { return true; }
virtual ostream& print(ostream& os) const { os << (*this); return os; }
friend ostream& operator << (ostream& os, const PtObj& pt)
{
os << "POINT(" << pt.pt[0] << "," << pt.pt[1] << "," << pt.pt[2] << ") ";
return os;
}
};
class ColObj : public Obj
{
float col[3];
public:
ColObj(float r, float g, float b) { col[0] = r; col[1] = g; col[2] = b; }
virtual bool isColor() { return true; }
virtual ostream& print(ostream& os) const { os << (*this); return os; }
friend ostream& operator << (ostream& os, const ColObj& col)
{
os << "COLREF(" << (int)col.col[0] << ","
<< (int)col.col[1] << "," << (int)col.col[2] << ") ";
return os;
}
};
int main(int argc, char ** argv)
{
std::vector<Obj*> myVec;
PtObj* ppt = new PtObj(3, 3, 3);
myVec.push_back(ppt);
ColObj* pcol = new ColObj(255, 128, 128);
myVec.push_back(pcol);
cout << (*myVec[0]) << (*myVec[1]) << endl;
for (int i = 0; i < myVec.size(); ++i)
delete myVec[i];
return 0;
}
Derived objects are type-safe while unions are not. So you couldn't change a PtObj to a ColObj.
Regards, Alex
Business Accounts
Answer for Membership
by: jkrPosted on 2004-11-07 at 19:20:19ID: 12520517
'myVec.end()' will return a 'pseudo iterator' that os special for indicating the end of the vector - you should use
vertex v;
std::vector<vertex> myVec;
v.pt[0] = 3;
v.pt[1] = 3;
v.pt[2] = 3;
myVec.push_back(v);
vertex temp
temp = myVec.back();
This member function returns a reference to the last element of the vector.