C :: Arrays And Pointers In A Loop

Jun 27, 2013

Set an Array (a[10]) and a Pointer to that array (*pa) and code a loop (for( ; ; loop) that will advance that pointer (*pa) and will set a new content into it with each loop. that means that in the end of the day, my program will automatically set content to each cell of the array by promoting the pointer by 1 and add the sum to that pointer.

When I run the program it prints the address of the cells instead the value of it.

Code:
#include <stdio.h>
void main() {
float a[11], *pa; // Array and ptr set.
int i; // counter for the loop.
pa = a;
for (i=0 ; i<=10 ; i++) // the loop itself.

[Code] .....

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C++ :: Dynamic Creation Of Arrays Of Pointers To Arrays Of Pointers

Apr 15, 2013

I'm trying to write a function that takes a 32bit address and a data to store at this address.

I'm wanting to take the 32 bit memory address eg 0x12345678 and split it
into 4 x 2 bytes
12, 34, 56, 78

then each of the 4 entries is at most a 256 entry array.eg
FF, FF, FF, FF

So in this example, 0x12 points to 0x34 in the second array, which points to 0x56 in the third array, which finally points to 0x78 in the last array. This last array holds the actual data.

After successfully doing 0x12345678, say I might get a read for 0x1234AABB. So, the first and second pointers already exist, but I then have to create and write to dynamically created arrays.

The arrays need to have all entries set to NULL so that i know whether to follow the pointers to overwrite a previously entered value or create new arrays and pointers.

It all looks good and simple in the pseudo code I've written up but I'm having trouble coding it. I'm currently trying to deal with the first entry case, ie all array elements are NULL, but I'm getting confused with the pointers and creation of new arrays.

void cpu::store(unsigned int mem_add,unsigned int mem_val) {
int first = (mem_address&4278190080)>>24;
int second = (mem_address&16711680)>>16;
int third = (mem_address&65280)>>8;
int fourth= (mem_address&255);

[Code] .....

A1 has been declared as
int* A1[256] ;

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C++ :: Use Different Pointers For Arrays?

Dec 24, 2013

So when if you want to change the values themselves for example in an array (just for example) this is valid;

void test(int* test)
{
test[0] += 10;
}
int bob[] {1, 3, 5};

If you did that bob[0] would not equal 11. All well and good right?

Now if you do this?

int sally = 33;
test(sallay);

This wouldn't work at all you actually have to use

void test(int& test)
{
test += 10;
}

how the memory addresses etc. are working here? I don't understand why you need to use & the reference operator if it's not an array? Why wouldn't that still work?

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C++ :: Ranged For Loop With Arrays Of Arrays

Dec 17, 2014

int arr[4][5];
for (int(&row)[5] : arr){
for (int &column : row){
} }

Why do we name it row instead column?

int arr[row][column]

Wouldn't this be like

int arr[4][5];
for (int(&column)[5] : arr){
for (int &row: column){
}

It just seems funny to me because we use row[5] which should be 4 if we meant row? Or did I read it wrong in C++ prime !?

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C :: How To Use Character Pointers Instead Of Arrays

Apr 14, 2013

Here is my program to look up words. How do I use character pointers instead of using arrays?

Code:
#include <stdio.h>
struct entry
{

[Code].....

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C :: Dynamic Arrays And Pointers

Feb 11, 2013

I am having troubles with dynamic arrays and pointers. All the errors are of that kind. I think when I am assigning malloc to an array we assign to its address.

Code:
/*Create an array of genes of the large matrix*/
gene_t gene,gene1,gene2;
gene=malloc(INITIAL*sizeof(gene2)); Code:
while(...) {
if (gene_num==current_size){

[Code] .....

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C :: Merging Arrays Using Pointers

Jul 17, 2013

Merging two arrays together using pointers!

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C :: Accessing Arrays Using Pointers

Aug 30, 2013

I came across the below code snippet in a project and was not sure how value of variable "response" is computed. Here as we can see, pic_data holds two one dimensional arrays but "response" access both the single dimensional array as two dimensional array.

Code:

#define MAX 100
#define MAXBUF 100
u32 response;
u32 index;
}

[code]....

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C :: Pointers And Bi-dimensional Arrays

Feb 6, 2013

I have a problem with a pointer and a bidimensional array. Here's the code:

typedef char t_board[5][4];
int i,j;
t_board *copy (t_board b) {
t_board *ptr;

ptr = (t_board *) malloc (sizeof(t_board));

[Code] ...

After this, I print new_board, and its ok; but the following code after the call to copy, crashes. Don't know why. if I remove the statement new_board = copy(some_board); , the code that follows runs ok.

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C++ :: Arrays And Smart Pointers

Aug 3, 2014

I'm writing quite a large program that needs to work with very large arrays (up to 100 million integers). It is necessary that i can access every point of the array directly (without running through the array) and that I use as little memory as possible. I first wrote the program with pointers that point to allocated heap memory. It works fine but now I wanted to use smart pointers instead (so I'm sure to have no memory leaks). Here's a simple visualization of my problem:

#include <iostream>
#include <memory>
using namespace std;
unique_ptr<int[]> upArray;
int main() {
int nArrayLength = 10;

[Code] ....

There are 2 things that do not work how I would like the to:

1. It wants me to assign the heap memory in one step: unique_ptr<int[]> upArray(new int[nArrayLength]); But I'd like to have the unique_ptr in my Class_Declaration before I know the array length and allocate the memory later.
2. *(upArray + i) = i;
cout << *(upArray + i);

Those lines don't work! How else can I do it.

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C/C++ :: How To Use Pointers To Arrays In Function

Feb 25, 2015

I am trying to use pointers to arrays in my function.

I can get the pointers to work outside of a function but I just can't figure out how to make them work in my function.jwhittle58, on 25 February 2015 - 06:06 PM, said:

I am trying to use pointers to arrays in my function. I can get the pointers to work outside of a function but I just can't figure out how to make them work in my function.

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C :: Passing Arrays To Other Data Has Pointers?

May 7, 2013

I am looking for an example of when passing arrays to other data that has pointers,

I understand the terms I would just like to see a small example of code that actually demonstrates this process.

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C :: Functions Which Change Arrays Without Pointers?

Jan 17, 2014

the book I learn from gave a task to write a program which gets a matrix , and we have to write a function that switches 2 columns or rows the user inputs .as far as I know a function can not change variables in the main function without using pointers .so , theoretically, can a function described here can be written without using pointers ? as far as I tried - it can not.

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C++ :: Class With Pointers And Dynamic Arrays

Apr 25, 2014

Class with Pointers and Dynamic Arrays

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C++ :: Project Combining Arrays / Pointers And Structures

May 6, 2014

Write a program that uses a record structure to store a Student Name, Student ID, Test Scores, Average Test Score, and Grade. The program should keep a list of test scores for a group of 6 students. The program should ask for the name, ID, and four test scores for each student. Then the average test score should be calculated and stored. The course grade should be based on the following scale:

Average Test Score Course Grade
------------------ ------------
90 - 100 A
80 - 89 B
70 - 79 C
60 - 69 D
59 or below F

A table should be displayed on the screen listing each student's name, ID, average test score, and course grade. Implement with functions.

My code runs but it isnt returning anything (readable/correct) and i have no clue why. This is what i have so far:

#include <iostream>
using namespace std;
const int columns = 4;
struct StuRec //user defined datatype {
int id[6];
char names[6][20];

[Code] .....

it compiles completely but at the end instead of showing the student name ID average score and class grade it shows.... [URL] .....

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C/C++ :: Project Combining Arrays / Pointers And Structures

May 5, 2014

Write a program that uses a record structure to store a Student Name, Student ID, Test Scores, Average Test Score, and Grade. The program should keep a list of test scores for a group of 6 students. The program should ask for the name, ID, and four test scores for each student. Then the average test score should be calculated and stored. The course grade should be based on the following scale:

Average Test Score Course Grade
------------------ ------------
90 - 100 A
80 - 89 B
70 - 79 C
60 - 69 D
59 or below F

A table should be displayed on the screen listing each student's name, ID, average test score, and course grade. Implement with functions.

My code runs but it isnt returning anything(readable/correct) and i have no clue why. This is what i have so far:

#include <iostream>
using namespace std;
const int columns = 4;
struct StuRec //user defined datatype {
int id[6];
char names[6][20];
int scores[6][4];
double avg[6];
char grade[6];
}; //semi-colon required

[Code] ...

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C :: For Loop Controller Using Pointers?

Jan 3, 2015

I'm familiar with the concept of int in the for loop. However, I've seen a case where the condition for the for loop is a pointer. How is the pointer used or interpreted in the for loop condition in C or C++.

As an example:

Code:
void printer(char *fmt, ...) {
va_list args;
char *p, *sval;
int ival;
double dval;
va_start(args, fmt);
for(p = fmt; *p; p++) {
if(*p != '%') {
putchar(*p);
continue;

[Code]....

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C :: Sorting Arrays Of Pointers - Assigning Data To Gene

Feb 11, 2013

Code:
typedef struct {
name_t name;
float beta[beta_num];
} gene_t;

[Code] ....

Is gene an array of address ? How come the compare function doesn't work ?

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C++ :: How To Use Dynamic Memory Allocation And Pointers To Iterate Through The Arrays

Dec 21, 2014

I need to use dynamic memory allocation and use pointers to iterate through the arrays that I have already in this program. I am lost, nothing I do works and where to use the pointers. I am just looking for a push in the right direction so I can finish this project and how I can implement pointers in my program.

#include <iostream>
#include <string>
#include <cstdlib>
#include <iomanip>
#include <stdio.h>
using namespace std;

[Code]...

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C/C++ :: Why Do Void Function Pointers EXECUTE Arrays Of Hexcode

Dec 23, 2012

I know how to use functions pointers in C and C++ and I know if you have something like

char buf[] = {
0x48, 0xb8, 0x3c, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x48, 0xbf, 0x02, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x0f, 0x05
};
((void (*) (void))buf)();

That this will execute those binary instructions in hexadecimal notation BUT WHY? I don't get why that works since that's an array of data not a function?

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C/C++ :: Using Pointers For Character Array In For Loop

Nov 3, 2014

I'm taking an intro to programming course and my assignment is to Write a very simple program that uses two for loops and ONLY pointers and pointer arithmetic (NO other variables are allowed) to display a palindrome forward then backward. Declare the palindrome as follows: char str[] = “Straw Warts”; Well my prof never did anything with char arrays and I can't quite fit make the pointers work in the loop. This is my code. It runs how it should, i just can't seem to make a working for loop. It always says that you can compare int and char

#include <iostream>
using namespace std;
int main()
{

[Code]......

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C++ :: Displaying Correct Output By Using For Loop (with Pointers)

Feb 4, 2014

I wanted to display the correct output by using a for loop at the end of my code, but for some reason it's not working correctly.

#include <iostream>
using namespace std;
int main() {
int* ipArray[3];
for(int i = 0; i < 3; i++) {
ipArray[i] = new int [5];

[Code] .....

What I wanted to do is pretty much match my 1st out put like 0 1 2 3 4 but my 2nd output only outputs 24's and I don't know why

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C++ :: Pointers And Arrays - Program To Display Sorted List And Average Of Scores With Appropriate Headings

Apr 22, 2014

I am writing a class that dynamically allocates an array that holds a user-defined number of test scores (test scores go from 0 to 10 both included). Once all the test scores are entered and validated (values only between 0 and 10, both included), the array should be passed to a function that sorts them in ascending order. Another function should be called that calculates theaverage of all the scores.The main program should display the sorted list of scores and the average of the scores with appropriate headings.

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C++ :: For Loop To Sum Up Product Of Several Arrays

Feb 2, 2013

I need a for loop that sums up the product of several arrays.

int total = 0;
for (int i=0; index < (columns - 2); index++)
for(int indexFF = 0; indexFF < CG[index + 2] - 1; index++)
for (int indexIN = 0; indexIN < CG[index + 1] - 1; indexIN++, total++)
NRN[CG[index + 1]+indexFF] += FF[total] * NRN[indexIN + CG[index]];

right now "columns" is set to 3

CG[] is an array of 10 integers for "column groups"

for now they are set to:

CG[0] = 0
CG[1] = 3
CG[2] = 4
CG[3] = 3

NRN[] is an array of floating points
NRN uses CG to map its indexes out

0 3 7
1 4 8
2 5 9
_6

FF[] is an array of random numbers basically constants

I need the for loops to sum:

NRN[0] = 0.5
NRN[1] = 0.75
NRN[2] = -1
NRN[3] = NRN[0]*FF[0] + NRN[1]*FF[1] + NRN[2]*FF[2]
NRN[4] = NRN[0]*FF[3] + NRN[1]*FF[4] + NRN[2]*FF[5]
NRN[5] = NRN[0]*FF[6] + NRN[1]*FF[7] + NRN[2]*FF[8]
NRN[6] = -1
NRN[7] = NRN[3]*FF[9] + NRN[4]*FF[10] + NRN[5]*FF[11] + NRN[6]*FF[12]
NRN[8] = NRN[3]*FF[13] + NRN[4]*FF[14] + NRN[5]*FF[16] + NRN[6]*FF[17]
NRN[9] = -1

NRN, FF and CG are the only things in other code that I can't change in the loops

when I debug it index goes to 3 and overflows its memory. which it shouldn't because columns = 3 so "index < (columns - 2)" should stop at 1

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C/C++ :: Storing Values In Arrays Using For Loop

Nov 18, 2013

I am trying to create a program that will give me an value for a chosen from the user array ut I believe the program I've made does not recognize the values of the previous arrays. (Here is my program):

#include<stdio.h>
int main() {
int n;
int i;
int j;
float c;
float a[10000];

[Code] ....

There must be problem cause every value I give n(only for n=1 the answer is correct) the result is "a[n] is -inf"

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C :: Create Array Of Pointers To Pointers Which Will Point To Array Of Pointers

Feb 28, 2014

I'm trying to create an array of pointers to pointers which will point to array of pointers (to strings) I tried

Code:

int i;
char *string[]={
"my name is dave",
"we like to dance together",
"sunny day",
"hello",

[code]...

the app keeps crashing , I don't know how to make the array-elements to point to another array-elements..

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