how can i store address of array elements in an another array element

[tekinalp67]

hi,
i am trying to implement a B+ tree. There is no specification in the implementation so i am using arrays to implement the B+ tree. However, there is a problem that i encountered which is I cannot store the address of an array element in an another array element. it is purpose is reaching the childs. The other thing that i want to mention is that the bucket size of the b+ tree is not specific. It will be determined at the beginning of the program. For example it can store 4,6 or 10 data. it does not matter. Here is my code any help will be appreciated.

#include<iostream>
#include<stdio.h>
#include<stdlib.h>
using namespace std;
#define length(a) (sizeof a / sizeof a[0])
class Node{
public:
    int count;
    int leaf;
    int *data;
    int *pointer;
    Node(int a){
        leaf = 1;
        count = 0;
        data = new int[a];
        pointer = new int[a+1];
 
    }
};
void insert(Node *node, int data, int line){
    Node *temp = new Node(line);
    temp = node;
    int i = 0;
    if(temp->leaf == 1){
        if(temp->count != line){
            while(temp->data[i] < data){
                i++;
            }
            for (int j = line; j > i; j--){
                temp->data[j] = temp->data[j - 1];
            }
            temp->data[i] = data;
            temp->count++;
 
        }
        else{
            Node *temp2 = new Node(line);
            Node *temp3 = new Node(line);
            //temp->pointer[0] = &(temp2->data[0]);
            //temp->pointer[1] = &(temp3->data[0]);
            for(int i = 0; i < 2; i++){
                temp2->data[i] = temp->data[i];
            }
            for(int i = 2; i < 5; i++){
                temp3->data[i] = temp->data[i];
            }
            for(int i = 0; i < 4; i++){
                temp->data[i] = 0;
            }
            temp->data[1]=temp3->data[1];
 
        }
    }
 
}
/*void deneme1(){
    int a[3];
    int *b[4];
    b[1] = &(a[1]);
    cout << b[1] << endl;
    cout << &(a[1]) << endl;
 
 
}*/
 
int main(){
    Node *temp = new Node(4);
    Node *temp2 = new Node(4);
    temp2->data[0] = 2;
    cout << &temp2->data[0] << endl;
    temp->pointer[0] = (int)(&temp2->data[0]);
    //long x = &temp2->data[0];
    //temp->pointer[0] = &temp2->data[0];
    temp->data[0] = 3;
    temp->data[1] = 12;
    temp->data[2] = 45;
    insert(temp,34,4);
    for(int i = 0; i < 4; i++)
        cout << temp->data[i] << endl;
 
    cout << "benim  " << temp->pointer[0] <<endl;
 
    /*cout << sizeof(temp->data) << endl;
    cout << length(temp->data) << endl;
    cout << temp->data[0] << endl;
    cout << temp->data[1] << endl;*/
    return 0;
 
 
}
 

Thank you very much for your helps.

[AmeL]

Could you please put the code bracket around your code for readability; and write us the error message which compiler produce ( with line number ) to make us easy to solve your problem, if that is a syntax error ?

[archonmagnus]

hi,
However, there is a problem that i encountered which is I cannot store the address of an array element in an another array element.

I'm not sure what you mean by your statement. When I compile your code (using GCC version 4.1.2), I get the following output:

0x804a068
3
12
34
45
benim 134520936
 

In your code you have the following:

// This prints: "0x804a068"
cout << &temp2->data[0] << endl;
temp->pointer[0] = (int)(&temp2->data[0]);
...
// This prints: "benim 134520936"
cout << "benim " << temp->pointer[0] <<endl;
 

The observant reader will note that 134520936_(Dec) =0x804a068_(Hex ). So it seems you are correctly storing the address of an array element into another element. Am I understanding your inquiry correctly?

To make the comparison a bit easier, you could have used the lines:

// This prints: "0x804a068"
cout << &temp2->data[0] << endl;
temp->pointer[0] = (int)(&temp2->data[0]);
...
// This prints: "benim 0x804a068"
cout << "benim 0x" << hex << temp->pointer[0] <<endl;
 

[tekinalp67]

Could you please put the code bracket around your code for readability; and write us the error message which compiler produce ( with line number ) to make us easy to solve your problem, if that is a syntax error ?

Ok I will. But there is no error messages. The problem is cannot getting the address of desired element correctly.

#include<iostream> #include<stdio.h> #include<stdlib.h> using namespace std; #define length(a) (sizeof a / sizeof a[0]) class Node{ public:     int count;     int leaf;     int *data;     int *pointer;     Node(int a){         leaf = 1;         count = 0;         data = new int[a];         pointer = new int[a+1];     } }; void insert(Node *node, int data, int line){     Node *temp = new Node(line);     temp = node;     int i = 0;     if(temp->leaf == 1){         if(temp->count != line){             while(temp->data[i] < data){                 i++;             }             for (int j = line; j > i; j--){                 temp->data[j] = temp->data[j - 1];             }             temp->data[i] = data;             temp->count++;         }         else{             Node *temp2 = new Node(line);             Node *temp3 = new Node(line);             //temp->pointer[0] = &(temp2->data[0]);             //temp->pointer[1] = &(temp3->data[0]);             for(int i = 0; i < 2; i++){                 temp2->data[i] = temp->data[i];             }             for(int i = 2; i < 5; i++){                 temp3->data[i] = temp->data[i];             }             for(int i = 0; i < 4; i++){                 temp->data[i] = 0;             }             temp->data[1]=temp3->data[1];         }     } } void deneme1(){     int a[3];     int *b[4];     b[1] = &(a[1]);     cout << b[1] << endl;     cout << &(a[1]) << endl; } int main(){     Node *temp = new Node(4);     Node *temp2 = new Node(4);     temp2->data[0] = 2;     cout << &temp2->data[0] << endl;     temp->pointer[0] = (int)(&temp2->data[0]);     //long x = &temp2->data[0];     //temp->pointer[0] = &temp2->data[0];     temp->data[0] = 3;     temp->data[1] = 12;     temp->data[2] = 45;     insert(temp,34,4);     for(int i = 0; i < 4; i++)         cout << temp->data[i] << endl;     cout << "benim  " << temp->pointer[0] <<endl;     cout << "benim 00" << hex << temp->pointer[0] <<endl;     cout << *&temp2->data[0] << endl;     /*cout << sizeof(temp->data) << endl;     cout << length(temp->data) << endl;     cout << temp->data[0] << endl;     cout << temp->data[1] << endl;*/     deneme1();     return 0; }

In the line "temp->pointer[0] = (int)(&temp2->data[0]);"
thank you

[tekinalp67]

I'm not sure what you mean by your statement. When I compile your code (using GCC version 4.1.2), I get the following output:

0x804a068
3
12
34
45
benim 134520936
 

In your code you have the following:

// This prints: "0x804a068"
cout << &temp2->data[0] << endl;
temp->pointer[0] = (int)(&temp2->data[0]);
...
// This prints: "benim 134520936"
cout << "benim " << temp->pointer[0] <<endl;
 

The observant reader will note that 134520936_(Dec) =0x804a068_(Hex ). So it seems you are correctly storing the address of an array element into another element. Am I understanding your inquiry correctly?

To make the comparison a bit easier, you could have used the lines:

// This prints: "0x804a068"
cout << &temp2->data[0] << endl;
temp->pointer[0] = (int)(&temp2->data[0]);
...
// This prints: "benim 0x804a068"
cout << "benim 0x" << hex << temp->pointer[0] <<endl;
 

first of thank you for your reply.
I have question about the "x". what is it for
for example there is an output that i generate.
000221D8
3
12
34
45
benim 139736
benim 0x221d8
2
in here 000221D8 is not same with the 0x221d8.
Thank you again for your helps.

[tekinalp67]

I want to ask another thing. :)
For example and assume that in my code this line

temp->pointer[0] = (int)(&temp2->data[0]);

get the address of the temp2->data[0] to the temp->pointer[0]
after getting the address of the element how can I get the actual value in that address I mean which statement will give it to me.
The second question is how can i store the address of the elements in the insert method.
In the code lines
temp->pointer[0] = &(temp2->data[0]);
temp->pointer[1] = &(temp3->data[0]);
thank you. very much.
I cannot put code tag around the codes because then there are &nbps which I cannot correct. Sorry for the inconvience.

[JosAH]

For example and assume that in my code this line

temp->pointer[0] = (int)(&temp2->data[0]);

get the address of the temp2->data[0] to the temp->pointer[0]
after getting the address of the element how can I get the actual value in that address

That is all very unsafe what you're doing there: it assumes that sizeof(int) ==
sizeof(your pointer type). Better define a small union type that can safely hold
both (one of each) type.

kind regards,

Jos

[tekinalp67]

That is all very unsafe what you're doing there: it assumes that sizeof(int) ==
sizeof(your pointer type). Better define a small union type that can safely hold
both (one of each) type.

kind regards,

Jos

thank you very much. but i am beginner in c++.
Can you tell me how can i define a small union type.:)
if you can write that piece of code i will very happy:)
Thank you very much.

[tekinalp67]

 void deneme1(){
    int a[3];
    int *b[4];
    b[1] = &(a[1]);
    cout << b[1] << endl;
    cout << &(a[1]) << endl;
} 

In here one of the array is an int array the other is pointer of array. So there is no problem while storig the addresses.
How can I make the pointer of array to an array to not get the errors "1>------ Build started: Project: BPlusTreeSecond , Configuration: Debug Win32 ------
1>Compiling...
1>BPlusTree.cp p
1>c:\users\asus \documents\visu al studio 2008\projects\b plustreesecond\ bplustreesecond \bplustree.cpp( 15) : error C2440: '=' : cannot convert from 'int *' to 'int'
1> There is no context in which this conversion is possible
1>c:\users\asus \documents\visu al studio 2008\projects\b plustreesecond\ bplustreesecond \bplustree.cpp( 25) : error C2109: subscript requires array or pointer type
1>c:\users\asus \documents\visu al studio 2008\projects\b plustreesecond\ bplustreesecond \bplustree.cpp( 25) : fatal error C1903: unable to recover from previous error(s); stopping compilation
1>Build log was saved at "file://c:\Users\asus\D ocuments\Visual Studio 2008\Projects\B PlusTreeSecond\ BPlusTreeSecond \Debug\BuildLog .htm"
1>BPlusTreeSeco nd - 3 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
".

class Node{
public:
    int count;
    int leaf;
    int data;
    int *pointer;
    Node(int a){
        leaf = 1;
        count = 0;
        data = new int[a];
        pointer = new int[a+1];
    }
};

In the above on the line 5 data is an ordinary array. it is not a pointer of array. But then there are lots of errors I encountered. Is there anyone who can propose a better solution.
Thank you very much.

[tekinalp67]

Please some one help me...
I change my code so that I can store the address of the array elements in an array. However, there is another problem which i mentioned earlier is that I cannot reach the element that this address refers. This is my code:

#include<iostream>
#include<stdio.h>
#include<stdlib.h>
using namespace std;
#define length(a) (sizeof a / sizeof a[0])
class Node{
public:
    int count;
    int leaf;
    int *data;
    int** pointer;
    Node(int a){
        leaf = 1;
        count = 0;
        data = new int[a];
        pointer = new int*[a+1];
    }
};
void insert(Node *node, int data, int line){
    Node *temp = new Node(line);
    temp = node;
    int i = 0;
    if(temp->leaf == 1){
        if(temp->count != line){
            while(temp->data[i] < data){
                i++;
            }
            for (int j = line; j > i; j--){
                temp->data[j] = temp->data[j - 1];
            }
            temp->data[i] = data;
            temp->count++;
        }
        else{
            Node *temp2 = new Node(line);
            Node *temp3 = new Node(line);
            //temp->pointer[0] = (int)&(temp2->data);
            //temp->pointer[1] = (int)&(temp3->data);
            for(int i = 0; i < 2; i++){
                temp2->data[i] = temp->data[i];
            }
            for(int i = 2; i < 5; i++){
                temp3->data[i] = temp->data[i];
            }
            for(int i = 0; i < 4; i++){
                temp->data[i] = 0;
            }
            temp->data[1]=temp3->data[1];
        }
    }
}
void deneme1(){
    int a[3];
    int *b[4];
    b[1] = &(a[1]);
    cout << b[1] << endl;
    cout << &(a[1]) << endl;
}
int main(){
    Node *temp = new Node(4);
    Node *temp2 = new Node(4);
    temp2->data[0] = 2;
    cout << &temp2->data << endl;
    temp->pointer[0] = (int*)(&temp2->data);
    //long x = &temp2->data[0];
    //temp->pointer[0] = &temp2->data[0];
    temp->data[0] = 3;
    temp->data[1] = 12;
    temp->data[2] = 45;
    insert(temp,34,4);
    for(int i = 0; i < 4; i++)
        cout << temp->data[i] << endl;
    cout << "benim  " << temp->pointer[0] <<endl;
    //cout << "benim 0x" << hex << temp->pointer[0] <<endl;
    cout << *&temp->pointer[0] << endl;
    /*cout << sizeof(temp->data) << endl;
    cout << length(temp->data) << endl;
    cout << temp->data[0] << endl;
    cout << temp->data[1] << endl;*/
    //deneme1();
    return 0;
}

on line 11 i changed the code.
Please some one help me to fix this.
Thank you.