C++ :: Matrix Navigation Via Pointer
Oct 29, 2014
I want to navigate a 2D Matrix (for example: int iMatrix[10][10]), with a pointer.
I'm not sure how to traverse this matrix in both demensions with a single pointer.
I want to know because I'm going to pass a pointer of this matrix into a function and do work with it.
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Jun 20, 2014
i really don't know why has a error in my code, that pass a pointer of pointer (name of a matrix with 2 dimensions). Here is the source code of a simple example where appears segmentation fault when execute (but compiles normal):
#include <stdio.h>
#define LINHAS 3
#define COLUNAS 5
float a[LINHAS][COLUNAS];
void zeros(float **p,float m, float n){
int i,j;
for(i=0;i<m;i++)
[Code]...
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Mar 2, 2014
So I have assigned this method to each TextBox. It works fine pressing the left arrow and right arrow, but for some reason will not work using the up and down arrows. I have tested the string, using MessageBox and it is correct...the loop even proves it finds a matching TextBox. It is correct as in it displays the TextBox name it should be selecting but doesn't. I have no clue! Now the first select method is the one I want to use, I used the loop to check to see if it was even finding a match. It does find it but doesn't select it. The naming convention for my text boxes is r1c1 where the first number indicates the row and the second number is the column. There are 9 rows and 9 columns. This SHOULD be working but for whatever reason it is not. I've even put a message box inside the if statement for the up and down keypress check and it pops up when i press up or down.
private void Navigate(object sender, KeyEventArgs e) {
TextBox input = (TextBox)sender;
string nextBox = input.Name.ToString();
if (e.KeyCode == Keys.Left) {
if (int.Parse(nextBox.Substring(1, 1)) > 1 && int.Parse(nextBox.Substring(3, 1)) == 1)
[Code] ....
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Aug 8, 2012
How can a set a pointer , to a matrix example matrix[20][20] and iterate ( loop ) in each row first sort of X first and then Y through it using the pointer , how to setup dynamic allocation
through pointer = new matrix[20][20]
and finally call delete on pointer when done with the matrix.
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Nov 3, 2012
I developed a sample application in EF which has 3 tables
PersonDetails, BankDetails and FixedDepositDetails.
Please find the table structure below
create table PersonDetails
(PersonId int Primary Key,
PersonName varchar(30))
create table BankDetails
(BankId int Primary Key,
BankName varchar(100),
[Code] ....
But when I run the application I get an error as
The navigation property 'Bank_Id' is not a declared property on type 'FixedDepositDetails'. Verify that it has not been explicitly excluded from the model and that it is a valid navigation property.
If I am not wrong I think I have made some mistakes when creating the model.
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Mar 27, 2013
i want to know how i can solve this question? do i need to create a class or write the program codes.
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Jun 1, 2014
I just want to know the code of the program: Write code to accept matrix as aurgument and display its multiplication matrix which return its multiplication matrix.
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Feb 27, 2012
I want to assign a matrix to submatrix of a bigger matrix.
ublas::matrix<int> A(8,5);
ublas::matrix<int> B(2,5);
for(size_t i=0;i<A.size1();++i)
for(size_t j=0;j<A.size2();++j)
A(i,j)=i*A.size2()+j+1;
for(size_t i=0;i<B.size1();++i)
for(size_t j=0;j<B.size2();++j)
B(i,j)=i*B.size2()+j+5;
ublas::matrix_range<ublas::matrix<int> > a(A,ublas::range(0,2),ublas::range(0,5));
a=B;
and it works.
but if the matrix is compressed_matrix type, there's something with it. the error log as below:
Check failed in file boost_1_48_0/boost/numeric/ublas/detail/matrix_assign.hpp at line 1078:
detail::expression_type_check (m, cm)
terminate called after throwing an instance of 'boost::numeric::ublas::external_logic'
what(): external logic
Aborted
I'm not sure this is a bug or not.
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May 25, 2014
I have to prepare a project. But I don t know how can I do this. Program will find a matrix P for a square matrix A such that P^-1 A P ....
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Oct 4, 2014
3 3
2 1 3 2 3
1 0 2
1 2 6
First line shows row and column number
First index of the second line tells the number of non-zero entries of the first row and second index tell the column number where the non zero entry is placed
for 1st row of matrix:
non-zero entries=2
column number=1
non-zero entry=3
column number=2
non-zero entry=2
covert this in the given form
0 3 3
2 0 0
0 0 6
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Jan 17, 2014
I was having problems changing the value of my head node I passed it as an argument as head which would be the address. The parameter was defined as struct node *head. like this
bool deleteNode(struct node *head, struct node *delptr)
I tried manipultaing pointer values to change head node value but it did not work. I saw some code online which used pointer to pointers(in code below) to change head node value it worked I dont fully understand why. Would like better understanding of why.
Would also like to know why the argument call needed &head instead of just head.
remove = deleteNode(&head,found); opposed to remove = deleteNode(head,found);
#include "stdafx.h"
#include<iostream>
struct node{
[Code].....
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Aug 19, 2014
I am attempting to implement function pointers and I am having a bit of a problem.
See the code example below; what I want to be able to do is call a function pointer from another pointer.
I'll admit that I may not be explaining this 100% correct but I am trying to implement the code inside the main function below.
class MainObject;
class SecondaryObject;
class SecondaryObject {
public:
[Code]....
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Nov 27, 2013
I have to write a program to print pascals triangle and stores it in a pointer to a pointer , which I am not entirely sure how to do. I also have to write the file and read it, then create a binary file. Assignment is attached. I am not the best with programming and especially with pointers. I will post my code below.
Code:
#include <stdio.h>
#include <stdlib.h>
void writePascalTriangle(char *fileName, int heightOfTriangle, int **triangle) {
FILE *fp;
fp=fopen("writePascalTriangle.txt", "w");
[Code] ....
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Apr 19, 2014
I'm making a system like twitter for class called ShoutOut.com I want to be able to get the PublicShoutOut pointer pointed to by the start iterator and assign it to firstShoutOutToDisplay and secondShoutOutToDisplay because I need that in order to pass the pointers to one of my functions. When I step through the debugger the values in start are all default values like "" and so are the values in this->firstShoutOutToDisplay but the message that start points to is being output just fine.
EDIT: got rid of irrelevant code. Am I using the correct syntax to do this?
if (start != finish) {
//getting these because a shoutout needs to be passed to the function that displays
//options for a shoutout
this->firstShoutoutToDisplay = (*start);
[Code] ....
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Mar 7, 2013
I have a function:
const void insertStuff(const void *key, const int value){
// I want to convert the void pointer into one
// of three types of pointers(int, string, or double)
switch(value){
case 0:
int *intPtr = key;
[Code] .....
But this causes an error of: "crosses initialization of int*intPtr"
What's the correct way of implementing this?
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Dec 25, 2013
i have been fiddling with pointers but I don't understand how the proper syntax is written when I want to acces an element of an array through a pointer to a pointer...The code is all mostly just random bs for learning purposes. I marked the problem "// THIS LINE"
Code:
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#define MAX_DATA 100
int find_average(char *iden, ...) {
[Code]...
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Jul 16, 2013
This is a sample program that declares a Matrix as a structure with an array as a pointer to a pointer. The following program is supposed to store a matrix in the structure "_Matrix" and later print the matrix just entered but it fails giving me a "segmentation fault". The sample code is given below
Code:
#include <stdio.h>
#include <stdlib.h>
struct _Matrix {
int row_size;
int col_size;
int **mat;
[Code] ......
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Mar 4, 2015
I need to make a copy of a string that is defined by char *full and copy it into a different pointer defined by char *duplicate. I have written code to do this however it will not work and i cannot figure it out my code is as follows:
char *duplicate = (char *)malloc(strlen(full) + 1);
strcpy(duplicate, full); /*Make second version of full*/
char *Ptr = strtok(duplicate, " "); /*Split duplicate up*/
I have a full program written but i know this is where the problem is because i have used printf statements to see where the program fails. I get no errors and it compiles successfully but it hits this point of the program and it just stops and windows automatically shuts down the program.
char *full is pointing to:
"To be, or not to be? That is the question:
Whether 'tis nobler in the mind to suffer
The slings and arrows of outrageous fortune,
Or to take arms against a sea of troubles,"
I need to duplicate the string because i need to use strtok but i will need the original string later on so i need an unaltered version.
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Jan 3, 2013
I have the following code :
Code:
#ifndef TDYNAMICARRAY_H
#define TDYNAMICARRAY_H
namespace Massive {
template<class T>
T **AllocateDynamic2DArray(int nRows,int nCols)
[Code] .....
I wish to know how to traverse or loop through a dynamic 2D array using pointer to pointer as returned by the code above. Like I would in a static T[20][20] 2D array.
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Oct 17, 2013
I have a 3x3x3 matrix with values hanging from 1 to 27.
The order is this: Code: m[0][0][0] = 1;
m[0][0][1] = 2;
m[0][0][2] = 3;
m[0][1][0] = 4;
m[0][1][1] = 5;
m[0][1][2] = 6;
.
.
.
m[1][0][0] = 10;
m[1][0][1] = 11;
m[1][0][2] = 12;
.
.
.
m[2][2][0] = 25;
m[2][2][1] = 26;
m[2][2][2] = 27;
Is there an easy way to compute the indexes given the value? For example, I know that the first index can be found by dividing the value by 9.0: Code: const int firstIndex = ceil(value / 9.0) - 1; What about the second and the third indexes? I couldn't find a pattern in the numbers, and I didn't want to iterate through the matrix (the indexes will be calculated many times).
The other option is to create arrays where the values will be indexes and the matrix indexes will be the values. I'm not sure if it is the best way though
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Mar 6, 2015
I've a code and it works on my linux laptop; however it doesnt work on a matrix server. Im getting error Code: file.c: In function CondCheck:file.c:40:3: warning: this decimal constant is unsigned only in ISO C90 [enabled by default] The code of the programme
Code:
#include <stdio.h>
#include <string.h>
#include <math.h>
/*DECIMAL TO BINARY CONVERTER*/
int BinaryConverter (int bina)
}
[code]....
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Jan 27, 2015
I wants to print matrix such that Consider that original matrix look like following
1 2 3
4 5 6
7 8 9
Now I want to print like following
7 8 9
4 5 6
1 2 3
we can use only two for loops.
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May 1, 2013
I'm writing a function that inserts a row into a matrix and deletes the last row.
But I'm having trouble. What do I need to add to this function:
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Apr 7, 2013
//matrix :
12 5 35 35 35 65 170
48 15 190 85 27 27 24
100 315 119 600 116 129 70
88 110 145 90 90 90 90
77 85 130 55 210 122 200
// the row :
152 152 149 155 170
// matrix after adding the previous row :
12 5 35 35 35 65 170
48 15 190 85 27 27 24
100 315 119 600 116 129 70
88 110 145 90 90 90 90
77 85 130 55 210 122 200
152 152 149 155 170
We use the pointer.
- Can I print out the irregular matrix?
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Mar 14, 2013
I'm trying to call a function via a function pointer, and this function pointer is inside a structure. The structure is being referenced via a structure pointer.
Code:
position = hash->(*funcHash)(idNmbr);
The function will return an int, which is what position is a type of. When I compile this code,
I get the error: error: expected identifier before ( token.
Is my syntax wrong? I'm not sure what would be throwing this error.
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Feb 6, 2015
I create an instance of a base class (not derived class) and assign it to base class pointer. Then, I convert it to a pointer to a derived class and call methods on it.
why does it work, if there is a virtual table?
when will it fail?
// TestCastWin.cpp : Defines the entry point for the console application.//
#include "stdafx.h"
#include <iostream>
class B
{
public:
B(double x, double y) : x_(x), y_(y) {}
double x() const { return x_; }
[Code] ....
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