knows if there is a ready made function in C++ to sort (numerically or alphabetically) multiple arrays based on a particular array?
i.e. Imagine you have multiple arrays or a multi-dimentional array containing data about users (name, age, etc.)
Is there a function that for example can sort it by name, and automatically shift the age so they still correspond to the correct user name?
I have a file which has records with 2 fields--one int and one float..what is the best way to sort it?
The sorting has to be based on the int field(the first field) (each time the program runs the file might end up with some hundreds of records).
A user is supposed to enter student name, id, and grade then sort them by name, id, or grade. I managed to get it to sort by name and id correctly, but not by grade.
Code] .....
#include <string.h>
#include <stdio.h>
struct student{
int student_id;
char name[30];
char grade[15];
[Code] ....
I'm attempting to build a column based database, and I'm new to C++ (just wanted to play around with building a column base database "for the fun of it"). I want to construct a very fast radix sort, that would allow me to quickly sort groups of columns based on integer values. My general preference is to take up more RAM to get more performance.
I'd like to build the radix sort by allowing 256 "buckets" to drop values in as I'm sorting. This allows me to sort through a group of 4 byte integers in only 4 passes. But assuming I'm trying to sort a large group of values (say 50+ million), I'm not sure what type of container to use for these. Also note I'm pretty unfamiliar with the "standard library", so below are my thoughts:
Vectors:
-Pros: Easy to use, and very fast for sequential and random access inserts / reads
-Cons: If they have to dynamically resize because a given vector wasn't large enough, this can apparently really slow performance. Unless I make another pass over the numbers before I start sorting, I wouldn't know how big to make individual the individual vectors. This means I either have to make them "too big" and waste space, or pay a performance price for either resizing, or scanning data first.
Lists:
-Pros: Seems like I wouldn't have to specify size ahead of time, so I could just easily insert values to a given list. Also, since I don't need random access reads (I'll ready the "0" list sequentially, then the "1" list, etc. they should work fine.
-Cons: I don't really know much about lists, but I'm not sure how easy it is to append a new value to the end of a list. I've read that standard library lists include both "forward" and "backward" pointers, which I don't need. Also, I find it hard to believe that there isn't some time taken up with memory allocation. If I build a list and append x million records in it, is it calling memory allocation routines x million times?
Or maybe there's another container type I should learn?
Again, my goal is to make this "fast", not "memory efficient". But having said that, the fastest way I could think of (use 256 vectors, each sized equal to the total number of members to be sorted) is just too much memory to burn - 256 times a vector big enough to hold millions of elements is too much.
I am trying to sort a student database by age,but i am not sure whats wrong i think it has to deal with tmpstudent variable.
Code:
void insertion_sort(StudentDB *db) {
int i;
for (i = 0; i < db->num; ++i) {
int j = i - 1;
int val = db->records[i].age;
[Code] .....
New file_sorter.c:
#include <stdio.h>
#include <stdlib.h>
#include "sort.h"
#include <string.h>
[Code].....
My issue is now a segmentation fault in my sorting algorithm. In my assignment I was suppose to implement quick and insertion sort for the file, and organised strictly by ASCII values. We were allowed to look up generic algorithms for the sorts, but we have to convert them to comparing char arrays.
I haven't started trying to configure quick sort yet, but I'll supply the generic algorithm as well. keep in mind that the first line in the file contains the number of lines in the file. I'll try not to disappear this time!
sort.c :
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
[Code]....
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] ....
I have a vector which contains vectors containing 7 integers each. I'd like to sort these vectors based on the value of the first integer (int IOT), in ascending order. I know this type of question can be found everywhere, but I'm lost as to why this doesn't compile.
#include <fstream>
#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <stdio.h>
#include <math.h>
#include <windows.h>
using namespace std;
class orders {
public:
int IOT; // Incoming Order Time
[Code] ....
I have a problem I am working on where I need to sort some data based on the values of a string of bits. The strings look like this,
010000001110000000
there are 18 bits, 1 means a feature is present, 0 means the feature is absent.
Each of these string has 4 on bits. I need to sort them such that I have the longest possible runs with 3 of the same on bits. It doesn't matter which 3 bits are on, I am just looking to order them in blocks with the longest possible runs. As a second step, the ordered blocks will be sorted by size large>small.
The following data is ordered like I need it to be.
Code:
// block 1, run of 12, keys 1,2,11 are identical (key 12 is also identical)
011000000001100000
011000000001100000
011000000001100000
011000000001100000
[Code] .....
This is the sort order that I am looking for. I need to be able to take a list of the bit strings in any particular order and sort them into the order above. The algorithm would need to recognize that there are 4 on keys and then look for groupings of three common on keys.
This is more of an algorithm question than one about specific implementation in code. I generally assume that most programming problems have been solved one way or another, so I don't know much about analyzing and manipulating strings of bits.
Is there a standard method for this kind of pattern recognition?
I have a piece of code that sorts data based on some metric. The some metric is something I now want to make flexible so I can easily switch between and compare metrics. To do this, I want to pass the function to use as a parameter to the method that does the sorting (and other stuff). However, I'm having problems figuring out the syntax. Also, I think my [temporary] organization of code is violating a lot of basic code design principles.
To make the function pointer passable, I defined the "typename" in the header where the function is located (it is part of a struct, "Data"):
// Below the struct definition of Data
typedef double (Data::*CostF)(unsigned l, double W) const;
The two example functions I want to use are defined in that struct ("Data"):
// Inside the struct definition
inline double someExampleCost(unsigned l, double W) const {
// Returns some basic calculation
}
The function that uses it is part of a different class (that holds a reference to the first class, in case that matters; I feel like I'm doing something odd here, because I'm binding a member function in the definition/passing, but never referencing the object). It looks like this:
// Inside another class ("Foo")
inline void DoSomeStuff(double& ECost, double& TCost, CostF cost) {
// Irrelevant stuff here
std::sort(vector.begin(), vector.end(), [&](unsigned a, unsigned b){
return (*cost)(a, W) < (*cost)(b, W);
});
// More irrelevant stuff here
}
The error shown is "operand of "*" must be a pointer". If I remove the '*':
[code]return cost(A, W) < cost(b, W);
the error becomes: "expression must have a (pointer-to-)function type."
The call to this function is, currently, just in the main function, as I'm just testing before I wrap it into real code. It looks like this:
// In main
Foo bar; // Make an object of the struct that has the "sorting" function
CostF costFunction = &Data::someExampleCost;
// Bind to the Cost function bar.DoSomeStuff(varA, varB, costFunction);
This bit shows no errors by itself. So, my questions:
a) Clearly I'm missing the insight into Function Pointers. I'm comfortable with regular pointer stuff, but I can't wrap my head around FPs, partly due to the awkward syntax.
b) I'm very uncomfortable with the fact that I'm binding a member function of a class, but never try to reference an actual object of that class. This is probably a big part of why it's not working, but I can't seem to bind a function belonging to a specific object. I thought of doing
// In the main again
Data d; // Construct the object, which contains big lookup tables
Foo F(d); // Construct the object, which only holds a reference to a Data object
CostF costFunction = &d.someExampleCost; // Bind to the Cost function of that object
but that doesn't work ("a pointer to a bound function may only be used to call the function").
I've been working on this assignment and but I know that I'm not handling my array properly.
#include<conio.h>
#include<iostream>
#include<stdio.h>
using namespace std;
class binaryTree {
[Code] .....
I first want to say that i am trying to solve my code without Pointers.
My goal is to..
1. Construct an empty 2D array with a capacity of 25. (list[25][2];)
2. Empty(): test if the stack is empty
3. Push(): add a value to the stack in the (list[i][0] = value;) position and (list[i][1] = previous list[i][0] position)
4. Top(); read the value(list[i][0]) at the top(count) of the stack
5. Pop(); remove the value at the top of the stack (list[i]= 0;)
6. Display(); displays all the elements in the stack going from the top to bottom order. (shows array index, data value, and next array index)
I have hit a road block and don't know what to fix or where to go from here.
#include <iostream>
#include <cstdlib>
#include <ctime>
using namespace std;
char name[5];
srand(time(0));
//Protoypes
void construction(int table[25][2]);
[Code]...
I'm trying to open a text file from my computer and randomly output a random line of text (string) onto the console. How do I go about doing this?
So for example, if my text file, "StringTextFile.txt" had 50 rows of strings datas (not integers or chars), how would I randomly generate a line of word from the 50 rows of words in the StringTextFile.txt and output it onto the console?
This is how far I've gotten, which isn't much, but somewhere. I don't even know if my code even makes sense, at this point I'm just randomly shoving code together.
#include <fstream>
#include <iostream>
#include <string>
#include <iomanip>
#include <string>
#include <cstdlib>
#include <ctime>
[code]......
I am trying to create a code to sort an array of integer, but only between two positions of the array, not the all array.
like this:
array: 1 2 5 4 7 2 9 8
index: 0 1 2 3 4 5 6 7
i want to sort the array per exemple between the the index 2 and 5.the result is... array: 1 2 2 4 5 7 9 8
I'm using a database and im trying to sort a 2D array info[51][10] that contains 51 pieces of records and 10 different fields for each record. And, now I'm trying to sort a desired field in the 2D array alphabetically.
However, the other fields within the same record should be swapped together. (So that the information of the same records stays together).
Also, I am constantly experiencing a run-time error. Sometimes my program works sometimes the whole thing crashes... By opening the code in different folders sometimes works. But the problem is still here. Is there any way to fix this error?
bool swapped =true;
int j=0;
string tmp[10];
swapped =true;
j=0;
[Code] .....
I have a class called Book and I am trying to create a dynamic pointer based array of the class. When I try to run the program I keep getting the error: pointer being freed was not allocated at the line of code that says "delete [] A;". I am using Xcode to run the program.
Book *changeArraySize(Book *A, int &size, double factor) {
int i;
int newsize = size*factor;
Book *A2 = new Book[newsize];
[Code] ....
I was writing generic class Array (based on counting access to elements)and i got compiling error I cannot even understand (in vs2012).
Code: [URL] ....
Error: [URL] ....
I tried sorting arr2 from lowest to highest value, but it only gives me 4 values and then the rest are zero.
Code:
#include <iostream>
#include <iomanip>
using namespace std;
int main()
{
cout << fixed << setprecision(1);
[code].....
Selection sorting a 2D array . Let's say i have an array like
1 2 3 4 //4 elements
1 2 // 2 elements
1 2 3 4 5 //5 elements
1 2 3 //3 elements
1 //1 element
And I want to do a selection sort it in descending order which the row with 5 elements will come first then 4 then 3 and so on. So that it would look like this
1 2 3 4 5
1 2 3 4
1 2 3
1 2
1
Code:
void selectionSortDescending(int list[MAX_ROW], int size){
int temp;
int walk;
int curr;
int large; // index of the largest element
for (walk = 0; walk < size - 1; walk++)
[Code] ....
I am trying to sort an array of size 10. If I was given:
Code: int List[Size] = {29, 11,12,10,3,26,13,15,19,2};
I need the program to sort all the odd integers and put the even integers to the back of the array. Like so:
Index: 0 1 2 3 4 5 6 7 8 9
Value:29 11 3 13 15 19 12 10 26 2
And it returns the number of even integers in the List. In this case it returns 4. All I am given to start with is
Code:
int evensToRead(int* const List, const int Size){
//body
}
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]...
i need to print the names as they appear in the original file, print the info of the person with the highest distance, print the info sorted by ascending ID number, and print sorted by name alphabetically. the first two parts work fine but sorting by ID and Name dont work.
#include <iostream>
#include <fstream>
#include <stdlib.h>
#include <string.h>
#include <math.h>
[code]....
I have a question about sorting a 2D array. Lets suppose I've got the following array:
2 5 7 4 8
3 11 14 5 2
6 3 12 9 1
7 15 11 4 2
8 16 13 5 1
I would like to sort this array diagonally to make it look as : [URL] ....
Here is what I have, I have a 1D Array being added to a 2D Array and I need to Sort them by value value 3 in the 2D Array, while maintaining a specific amount. Here is what I have so far:
public static void CheckHS(string[] HS) {
try {
GeneralData.HighScores[10, 0] = "11";
GeneralData.HighScores[10, 1] = HS[1];
GeneralData.HighScores[10, 2] = HS[2];
GeneralData.HighScores[10, 3] = HS[3];
//Need Sort Data - Bubble Sort?
}//end Try
catch (Exception ex) { MessageBox.Show(ex.Message); }
}
I am thinking bubble sorting but I remember reading about something faster. Unfortunately I can't find it on the web. The idea is that there will be always 10 Values and 4 Columns on the 2D Array. [The 11th Row being empty at the end of it.
How to sort a 2D array diagonally? Lets suppose I've got the following array:
2 5 7 4 8
3 11 14 5 2
6 3 12 9 1
7 15 11 4 2
8 16 13 5 1
I want to create a function that sort them diagonally like this: [URL] .....
I need to sort the elements in a 2d array by their index (starting from 1) for example:
Code:
1 5 3
4 7 8
4 10 2
10 is the biggest element and its index is 32, after 10 comes 8 with index 23 etc etc...
Looking for examples for two orders ... By descending and ascending order...