I have two doubts in the following code,the doubts are marked..PLs note that the following code is correct .This is a program to read 2d array using pointer ()i.e Dynamic array ,to calculate its rowsum and column sum and display this array along row sum and column sum.
#include<iostream.h>
#include<conio.h>
void main() {
clrscr();
int *Val,*Rsum,*Csum;
int MaxR,MaxC,i,j;
[Code] .....
I'm fairly new to C++ and have begun working with pointers. I wish to create am array called sigmaf_point that reads data from a text file. I have managed to get that working, but when it comes to using this pointer I come across some problems. The array is created as such:
Code:
double sigma [5];
double *sigmaf_point = sigma;
void read(double *&sigmaf_point)
string s;
ifstream Dfile;
std::stringstream out;
[Code] .....
I then create a coordinate system inside the main file, as the program I am writing is about modelling the movement of atoms, which requires you to know the coordinates:
Code:
int main();
double **coords_fluid = new double*[5000];
for (int i = 0; i < n_atoms_methane; i++) {
coords_fluid[i] = new double[4];
}
Now, the problem arises when I want to calculate a new variable as so:
Code:
for (int i = 0; i <= n_atoms-1; i++) {
sf1=sigmaf_point(coords_fluid[i][3]);
}
I get the error C2064: term does not evaluate to a function taking 1 arguments, and a red line under sigmaf_point that says it must be pointer to function type. I am a bit confused about this.
How can I Figure out and store the sum of EACH COLUMN in the 2D array values in a 1D array? And to the same for the average?
View 1 Replies View Relatedmy code is working as expected except a slight error, i have to find min max and median values of an inputed array terminated by 0, the problem im having is with calculating the minimum, where when i enter 0 to terminate the program it uses 0 as the minimum value. my code is as follows
public static void FindAverages()
{
try
{
[Code]....
I have a 2d array where I manage donations and requests for different foods. I output a menu to the user who picks the options to either make a donation, make a request, fulfill a request, or print a status report of all the donations and requests. What I'm having trouble with is the fulfilling requests option. When the user picks fulfill requests that means that the donations are supposed to be subtracted from the requests. For example if there are 10 donations for grains and 15 requests for grains then after picking fulfill request there should be 0 donations for grains and 5 requests for grains but I don't know how to make the program do that since the values are in a 5 row by 2 column array. The five rows correspond to the five foods and the two columns correspond to donations and requests, respectively. Here's my code so far. Just disregard everything but the third case.
Code:
#include <stdio.h>int main(){
int foodbank[5][2]= {
{0,0},
{0,0},
[Code]....
i have a matrix containing a lot of points and each point has its coordinates x and y. That is a nx2 size array. I want to sort it according to the first column ascending, with x coordinates. For points that have the same x coord i would like to sort according to y coord. Here is what i did and i cannot get a good result.
Code:
#include <stdio.h>
#include <stdlib.h>
int main(){
int a[5][2] = {{1,0}, {4,2}, {2,4}, {8,6},{4,8}};
int temp=0;
int i=0;
int j=0;
[Code]...
Now this issue is about calculating the average of numbers and displaying it in the out put.
The following numbers is what I have read in from a file. There are 7 lines all the same format, just different values of course.
132475.889.392.3
435686.383.498.3
The output will need to look like:
Student #Test1Test2Test3Average
132475.889.392.385.8
435686.383.498.389.3
My program thus far is: (omitted code to shorten post and remove irrelevant information.
I don't know if it is because I have been working on other things and forgot how to proceed with the calculations and display, but I am just stuck. I'm not sure how to have the program read the numbers from columns 2 through 5 and then divide by 3. As you can see in my DisplayAverages() method I should have the ConsoleWrite and WriteLines done properly.
static void Main()
{
double[,] scoresArray = new double[7,4];
LoadFile();
ReadData(scoresArray);
[Code]....
Should read columns 2-4 and then display the average in column 5.
This is for a 2-d array, but if i understand how to do it for a 1-d array, I can do it for a 2-d. So to keep it simpler, I will just pretend its for a 1-d array. I am working on a project where i must enter the month number of a storm and then tell the user which month had the most storms. So I have an array and the user determines the size of it by entering the number of storms. Then, using a for loop, the user enters the month number for each storm and the data is used to fill the array. This is to be used in a part of a much larger piece of code. I made a sample code below to mimic what i want to do:
Code:
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char *argv[]) {
/*Declare variables, i is a counting index used in for loop if necessary*/
[Code] ....
I believe this involves making some temporary array but where to start ....
I need to calculate how often each letter appears in a text file from a function that is called from main() with an array of pointers to char and how many pointers there are in the array. The code i have so far is:
#include<stdio.h>
#include<string.h>
#include<ctype.h>
#include<stdlib.h>
[Code]....
I get no errors and it runs but it gives me the wrong output. I know my array is correct because when i print it in main() it is correct but each letter is incorrectly counted. When i give it the input .txt file of:
This is one line of a string
This is another
This is the third one
Wow heres another one
It counts a as 8
b as 1
c as 3
etc.
I have hand traced it and cant figure out why it isnt giving me correct values
I am attempting to read values from a file into a 2d array temp[31][2] (31 rows, 3 columns).I only want the values from the file to be read into the first two columns.I believe I am accomplishing that but when I go to print the array, I expect the first two columns to have the file data and the third column to have all zeros. The third column, however is printing such that the value is the next row/first column.
I'm not sure for instance why on the bottom loop for line 1 it doesn't print:
temp[0][0] temp[0][1] temp[0][2] 20 49 0 It instead prints: 20 49 1
Code:
#include <stdio.h> Code: #include <math.h>
FILE *inptr;
int main() {
int temp[31][2] = {0}, tempavg[31][2] = {0};
int i, j, k, sum;
inptr = fopen("ProgrammingProject14.txt", "r");
[code]....
I am trying to store each value of a column from a text file into an dynamically allocated array, which needs to be globally declared for further usage in the program.The input textfile contains the following:
34932 13854 13854 2012-01-07
172098 49418 53269 2012-01-07
I have written the following code:
Code:
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int main()
}
[code]....
The commented printf line gives the entire values of the column, which proves that the file is correctly being read.But on compiling this program I get both compiler warnings and finally segmentation fault.
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]...
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] ......
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.
In my refference book I have got a example with a part saying to access the a[4][0] element of the array (named a) with pointer this can be written:
*((int*)a+4)
I wonder if the cast is really required. The book says it is required so that the pointer arithmetic can be done properly. However I am not sure about it. When I work with pointers defined by myself I don't use casts similar to this one. Is there a difference between a self defined pointer and array name?
I have written this code, and at first glance it does what I want, however I am worried that
a) I am overwriting the array that is apssed from chord.getPattern()
b) Im getting a memory leak that I want to get rid of, and
c) is there generally a /what is the neater way to do it:
Code:
uint8_t* ChordBuilder::invert(uint8_t count, Chord chord) {
temp = chord.getPattern();
chord.invert(true);
//TODO count is how many times to invert. Moves root aswell however
for (uint8_t i = 0; i < count; i++){
[Code] ....
temp is a member variable of ChordBuilder - and is expressed as: Code: uint8_t* temp; I dont want the pattern that chord stores, and passes with getPattern() to change - I fear it is at the moment?
I would rather not use the "new" but I cant think how to get rid of it, however Im not sure where I would need to put the "delete"?
What is the correct method of declaring pointer to multidimensional array
Code:
int array[3][4];
int *p = array;
The above code works but it shows warning. Is it an invalid way of using the pointer? the array is an address then why am i getting warning?
I have the following situation:
Code:
void myFun(float *pfMyPtr) {
float Val[] = {0.234, 0,432, 0.322, 0762, 0.984};
pfMyPtr = Val;
}
int main() {
float *pfPtr;
pfPtr = (float*) calloc (5,sizeof(float));
myFun(pfPtr);
}
I would like pfPtr to contain the values of array Val. What am I missing here?
int * ptr = new int[5];
p += 2; //p now stores address of 3rd element in array
delete [] p;
what will be deleted??? all 5 elements or just 3rd, 4th and 5th elements of array(in result making a memory leak)
Why would you ever assign a pointer to an existing array?Take this link for example. URL....I understand that pointers use dynamic memory allocation so they are much more flexible then a built in array, but if you already have an existing array, don't you already have static memory allocation for that array? Why bother assigning a pointer? Regardless of the pointer, doesn't the program still allocate static memory to the array anyway?
View 3 Replies View RelatedI'm given a .cpp file (for homework), this file populates an array from a file, that contains only numbers, using the standard method of populating an array but I'm supposed to modify it so that the array gets populated using a pointer, pretty simple right? Not so for me, I think I'm still confused on the concept of pointers. Here's what I have so far...
int main()
{
const int MAX_SIZE = 10;
[Code].....
I like to use a Pointer to char array. And then I would like to do a Pointer Arithmetic by incrementing the Pointer. Finally I would like to see the Addresses of the Pointer to each of the char Array Elements. I had created a program below, but I am not getting any Addresses from my Pointer.
#include <iostream>
using namespace std;
int main () {
int ArraySize;
char ch[]= "This is a Char Pointer";
char* iPtr = ch;
[Code] ....
I'm just trying to get a handle on the uses of pointers here. Though clearly from my errors I'm missing a key concept. Here is my code: (You can assume that the array, "array_size" has values in it, I did this part in another function)
int main() {
bool **ptr_array;
int num;
int *array_size;
cin>>num;
[Code] ....
Once the program reaches the word[num] = false; some unhandled exceptions pop up.
I simplified my code a bit from my actual program and mixed up the loops, now the code should be in its correct form.
How would I go about having a pointer to an array element specificity a character in a c-string.Every thing I try will not even build.An array is already a pointer to the first location of the array right?
char *pHead;
char *pTail;
pHead = sentence[0]; <=== This wont build
pHead = &sentence[0];
pHead = sentence[0]*;
*pHead = sentence[0]; <===== this builds but is not storing anything
int sum(int (*ar2)[4], int size);
// I dont know what the ar2 is going on
int main(){
int data[3][4] = {{1,2,3,4},{5,6,7,8},{9,10,11,12}};
int total = sum(data, 3)
return 0;
}
I was struggling the last 2 days with this C script supposing to open a list of strings (input as fopen(argv[1])and allowing to access to any element of the list. I created an array *gcm[10000] and a pointer *(*gcm_ptr[10000] = &gcm. However, when I try to list whatever n[i], it always gives me the last entry.
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