C++ :: Dynamic Array Allocation For Test Scores
Nov 30, 2014
I was doing a side programming challenge in my workbook that asked me to dynamically allocate and array for test scores. So far I have an array that will accept an integer to allocate the amount of test scores and then will accept integers to populate the array, however when I try to cout the contents of the array the numbers are absurdly different than what was put in. Here's my code:
#include "stdafx.h"
#include <iostream>
using namespace std;
void main() {
cout << "How many test scores?" << endl;
int scores(0);
[Code] ....
And this is the output screen:
How many test scores?
4
Enter test score 1:
22
Enter test score 2:
33
Enter test score 3:
44
Enter test score 4:
55
-33686019
18472
55656634
201345063
Press any key to continue . . .
Why am I getting these crazy numbers? I've looked back and forth from examples in my book and it doesn't look like I'm doing anything wrong.
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Nov 14, 2013
I need to confirm that this problem cannot be solved without a pointer. Namely I need to read the rows and columns number from the user cin >> m, n and then use to declare an array int A[m][n];
However as m and n are not constants I am not able to do that. Is there a workaround? The following is the solution I came with BUT using a pointers which should be not the case.
// solution with using pointers as "int A[m][n]" does not work for me!!!
void TwoDimensionalArrayFunc(){
int m = 0;
int n = 0;
// instruct the users to enter array dimensions
cout << "Please insert value for m:";
cin >> m;
[Code] ....
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Dec 26, 2012
I need to write 2 functions:
1. MyMalloc
2. MyFree
___________________________
I have a 1000 bytes global array (which did not dynamic allocated).
I need to make "dynamic allocation" from this array.
For example - MyMalloc(50) ---> The program will allocate 50 bytes OF THE ARRAY'S SIZE.
------
MyFree(pointer) ---> I need to check if the pointer is in the array and free the space.
It should be managed by blocks. The array should also contain the manage variables (for me).
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Jul 27, 2013
I coded a program that takes some strings and lexicographically orders the strings and its substrings. I have used dynamic memory allocation technique and its working fine for all strings without consecutive same alphabets.I use a list in which a string is placed in its exact position by moving the others right.
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
#include <conio.h>
[code]....
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Dec 1, 2014
I am trying to read from a file the names, id numbers, and 4 grades of 5 stduents. Here is the code:
#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
const int GRADES = 4;
const int STUDENTS = 5;
struct StudentInfo {
[Code] .....
Here is the txt file:
Amy Adams
10111
97 86 78 95
Ben Barr
20222
89 81 73 87
Carla Carr
30333
79 71 63 77
Don Davis
40444
69 62 58 67
Edna Eaton
50555
63 51 62 48
When I run the program this is the output:
Amy Adams
10111
97
86
78
95
-842150451
-6.27744e+066
-6.27744e+066
-6.27744e+066
-6.27744e+066
and so on .....
Press any key to continue . . .
As you can see the program is reading the first students information and outputting that fine, but the rest of the students have bad values for output. I'm guessing it's something to do with the pointer, but I really can't figure it out, why it won't read all of the students info?
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Jan 12, 2014
I'm trying to basically have a user input the amount of test they want averaged, then have the user input the test scores. Send the test scores to a function and have them ordered in ascending then send it to another function that averages it. When I wrote the function I keep getting the address back instead of the actual values.
#include <iostream>
#include <iomanip>
using namespace std;
void arrSelectSort( int* [], int);
void arrAverage(int);
[Code] .....
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Jan 25, 2015
i have so far, and im having trouble finding a way to store 5 test scores for each student that has been entered. for example: enter name: chaotic enter id number: 12312312
Enter test score 1:
Enter test score 2:
Enter test score 3 etc.......
heres me code so far
#include <iostream>
#include <string>
#include <iomanip>
#include <cstdlib>
using namespace std;
[Code]....
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May 23, 2013
Suppose I wished to reallocate memory (resize) an array of pointers. Why does the following not work?(The program runs, yet yields a faulty segmentation error message. Why?):
Code: char **ptrarr = (char**) malloc(sizeof(char*))
Code: ptrarr = (char**) realloc(ptrarr, (capacity) * sizeof(char*));
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Nov 8, 2013
I'm now working on a class to handle matrices and matrix operations. I dynamically allocate a two dimensional array with its size as an input. My problem is that i need to resize the matrix structure (to fit to the size of a product of two matrices or to adjust the size after deleting a row or column for example). I make the resizing by deleting the allocated 2d array after saving its first element address to another pointer to pointer, after saving the useful data in an other array, then i use new[] operator to create a new 2d array using the same address of the old deleted array.
void My_matrix ::delete_row(int a) {
int i,j;
int buffer_row_index = -1; //note that our work is zero based, as we acess the private member of an object of the same class we are working on and we access to the array as it is (zero based) so if this variable is -1, it will be 0 when it enters for the first time and saves the data in the right position.
My_matrix buffer(number_of_rows-1,number_of_columns);
[Code] ....
I do this in a way that i think is unsafe. This code is sometimes unstable and gives an unhandled exception whose reason is unknown. I need to know whether this way is good enough or if there any other better ways.
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Jan 18, 2015
I'm completely new to pointers and have a homework assignment due where I'm supposed to create a user defined dynamic array for player scores. The only errors I'm experiencing is a C2109: subscript requires pointer type and only on the lines that use the int *score; variable (57, 62, 64, 69, 71, and 82). I've already tried adding = nullptr to the variable and that didn't work.
#include<iostream>
#include<string>
#include<iomanip>
using namespace std;
void players(string[], int[], int);
void average(int[], int);
[Code] ....
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Dec 2, 2013
Dynamic memory allocation in array in c programming. I am trying to make the user to choose the size of array they want to engage in the game.
However, i have remove the global variable which contribute the error to my code previously. Now I assigned all the arr individually but not using the global variable. However, i still not get the desired board i want. i still keep getting 9x9 array board.
And i also need limit the board size only from 4 to 9. And how do i do that.
Code:
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <conio.h>
#include <malloc.h>
#include <ctype.h>
#include <stdbool.h>
[Code] .....
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Oct 22, 2014
I was asked to create a C++ program that allows a user to take a test with series of different questions, and also retake the test if they choose to. I have been able to do that. But the other condition is to display the highest and lowest scores (highest and lowest correct answers) the user got, and in which test they got that score. For example, if the user takes the test 3 times, in which test did they get the highest score, and in which did they get the lowest score.
This is how far I went with the program. The code below only let the user take the test as much as they want, and tell them how many times they took it, and the last score they had. My idea is this, if I can make a variable store each test score, then I can compare them. But since there is no definite number of tests to be taken.
#include <iostream>
#include <string>
using namespace std;
void main() {
int correct = 0;
int wrong = 0;
[Code] .....
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Feb 11, 2013
Write a program that prompts for and reads in test scores. You may assume that valid test scores will be integer values between 0 and 100. You may also assume that the user will not enter more than 35 test scores. Use a preprocessor directive to define this value. User input will be complete when the user enters a -1 for the test score. When all of the test scores have been entered, the program will print out the scores. Use a while or do-while loop to read in the values. Use a for loop to print out the values.
Sample output:
Enter test score 1: 88
Enter test score 2: 67
Enter test score 3: 74
Enter test score 4: 94
Enter test score 5: 79
Enter test score 6: 56
Enter test score 7: -1
Number of scores entered: 6
Test scores entered : 88 67 74 94 79 56
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Jan 18, 2014
I need to sort these students based on their test scores.
My biggest problem is with my sort function. I am not sure of the syntax to call the items the proper way. I also don't know how to call the function properly as I know that i can't pass a int to a struct. Also not sure about the z malloc. Just threw that one in there.
Code:
struct student{
int id;
int score;
};
void sort(struct student* students, int n){
/*Sort the n students based on their score*/
[Code] ....
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Apr 7, 2013
I have created a program that allows for a user-defined number of test scores as input. After the user enters these scores, the program calculates the average test score. Here is my code:
#include <iostream>
#include <iomanip>
using namespace std;
// Function prototypes
double getAverage(double*, int);
[Code] .....
I am having trouble with the final part of my program. How do I pass the array of test scores to a function that calculates how many people got an A (90+) on the test? The final output should look like this:
The average of those scores is:
The number of A grades is:
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Aug 29, 2014
I'm a little lost with this program. The idea is to dynamically allocate an array and increase its size every time a new integer is inputted by the user. I believe it is a memory leak but as we have just started learning this I'm not sure how to recognise it. Sometimes I can input as many integers as I want other times 2 or 3 before it crashes. When I can input enough values i exit the loop and send it to the sort function and mean calculator function, all works fine there except the last number inputted becomes this huge value not hexadecimal though... As such I'm at a loss as what to look at next, so here you go:
#include <iostream>
using namespace std;
void SelectSort(int [], int);
float MeanCalc(int [], int);
float MedianCalc(int* [], int);
[Code] .....
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Jan 14, 2013
Below is the program I have written yet I can't seem to get it to work right.
// Purpose: generate a class average for entered test scores
// Input: # of tests, test scores
// Output: total number of tests, average score of tests
#include <iostream>
#include <iomanip>
using namespace std;
int main() {
//declare variables
short numberOfTests = 0;
[Code] .....
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Oct 28, 2013
so in declaring a display function prototype only that displays a student test scores in the format (student name tab number of scores tab test scores )
is this right?
#ifndef STUDENTTESTSCORES_H
#define STUDENTTESTSCORES_H
#include <string>
using namespace std;
class StudentTestScores{
private:
[Code]...
and also how do we call the display function if it is in a class from the header file onto the main cpp file.
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Jul 14, 2013
I have declared a global variable as pointer. The program performs certain number of iterations. After every iteration, the size of memory required for the pointer changes and this pointer variable is to be accessed by different functions. Now, here is my doubt:If I allocate the memory for this global variable in a function, will the contents of the memory be lost once I exit that function. In my opinion, it should not be the case as the dynamic memory allocation takes place in "heap" and should not be affected by the call of functions.
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Oct 1, 2014
Code to allocate the memory for my arrays in the create array function.
#include <iostream>
#include <cstdlib>
using namespace std;
typedef int* IntPtr;
const int NUMLABS = 4;
[Code] ....
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Feb 24, 2014
I have recently bought a copy of "Jumping into C++" and have come to chapter 14 ( dynamic memory location) and have a question.
On page 153-154 an example of dynamic allocation is given for array's of int. How would the code look like for strings or structs ?
The allocation was given by:
Code:
int *growArray (int* p_values, int *size)
{
*size *= 2;
int *p_new_values = new int[ *size ];
for ( int i = 0; i < *size; ++i )
{
p_new_values[ i ] = p_values[ i ];
}
delete [] p_values;
return p_new_values;
}
Sample Code I tried to use this for an array of structs but failed completely....
I used the following struct Code:
struct user{
int days;
string name;
};
and the allocation function (which does not work):
Code:
struct user *growarray (struct user *p_values, int *size) {
*size *= 2;
struct user *p_new_values = new struct user[ *size ];
for ( int i = 0; i < *size; ++i )
[Code].....
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Jul 3, 2013
I am creating a connect 4 game using dynamic memory allocation the question is;
Write a two-player game of Connect Four where the user can set the width and height of the board and each player gets a turn to drop a token into the slot. Display the board using + for one side, x for the other, and _ to indicate blank spaces.
I have created the board. However I am unsure as how to make a start on getting the players to make moves.
Code:
#include <iostream>
using namespace std;
char **create_table(int width, int height, char blank) {
char **p_p_connect4 = new char*[height];
for(int i = 0; i < height; i++) {
p_p_connect4[i] = new char [width];
[Code]....
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Oct 24, 2013
I'm writing a program involving a theoretical hotel. Most of the code is already written, but the part I'm having trouble with involves the very beginning of the code.
The program is designed to read in from an input file the hotel's ID number, the types of rooms it has, the Room Numbers of each room, the base rate for each room, and the rate of additional charge per person.
The code demonstrates inheritance for my Object-Oriented Programming class, as each type of room will inherit from generic class Room, but I can't seem to figure out how to make the double-pointer for dynamic allocation work.
The code is below.
Hotel.h
Code:
class Hotel{
int hotelID;
static const int MAX_SIZE = 101;
Room **rPoint;
[Code] ....
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Mar 12, 2014
The snippet below (or similar) compiles and runs OK but I am using Visual Studio C++ compiler. Are the lines where .nameFirst and .nameLast assigned kosher in ANSI C?
Also I am concerned about the memory allocation for these string constants. Does the runtime system put them on the heap? It doesn't seem that they are really constants since they are not defined before runtime.
Code:
#include "stdlib.h"
typedef struct
{
unsigned id;
char* nameFirst;
char* nameLast;
} myList;
[Code]...
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Apr 17, 2014
I'm having problems with this code:
#include <iostream>
using namespace std;
class Foo {
public:
Foo( int n );// Constructor
~Foo();// Destructor
int *ptr;
int N;
[Code] ....
I'm using Visual C++ 2008 version. The problem arises at the end, after the sentence 'system("pause")' is reached, which makes me think that the problem happens when calling the destructor. The destructor is called twice, the first time it's called is in the function print. The problem seems to be that the destructor can only be called once.
I know I can avoid this situation by defining the function print like this:
void print ( const Foo &f )
...
but I would like to know if there is some way I can do this keeping the definition that I've provided.
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Feb 6, 2012
I want to allocate dynamically classes from a table. There is a different number of class derived from the same father class. Actually I do:
Code:
typedef struct sSysFBList {
TCHAR name[64];
int dim;
SystemFB *fbExec;
}systemFBCalls;
[Code] ....
and so on. NOTE: SystemFB is the virtual father class, all the other are derived from it.
I would like to know if there is the possibility to define the type of the class in the systemFBCalls struct to avoid all these if - else if - else if
Code:
typedef struct sSysFBList {
TCHAR name[64];
int dim;
????? name_of_class;
SystemFB *fbExec;
[Code] .....
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