C++ :: Use Vector Or List For Database System
Jul 28, 2014
I am making a console based database system. Because I have to keep inserting, editing , deleting data blocks from my record file I have decided to use either vectors or list to store the all records. From the file I shall read the entire vector/list and work with it to add , remove or edit record and then again write the entire vector/list to the file again. I figured it would stop all the weird things that happen when directly working with the file. Is it an efficient way ?Or is it totally unnecessary ?Is there a better way?
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Aug 28, 2013
i am trying to make a simple log in system without the use of database or whatever it is called.
my only concern is this
cout<<"enter password:";
cin>>pass;
how would i be able to make the characters appear as **** rather than the actual character that i would type as i am typing my password in CIN? or is it even possible?
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Aug 22, 2014
Which is best option to save images in database or file system, I am developing c++ server client app. I want to save the images in server using file system or database. I am confusing to choose which option?
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Aug 9, 2013
I wrote an application with wpf and c sharp. And I use ado dotnet framework to connect the database. Now the problem is I want a centralize database for the application. And I hav e installed sql server on one of the which I want to serve as server. I now want all other clients to be able to connect to the database through local area network. how will I do that?
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Mar 6, 2013
I've remade a program to store student database using linked list. When I try to display the list of student with their information (It displays nothing)
Code:
#include <iostream>
#include <string>
using namespace std;
struct StudentRecord {
[Code] ....
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Feb 17, 2014
I wanted to retrieve all rows from database and display in listview using list<string>
con.Open();
MySqlCommand view = new MySqlCommand("Select Cust_ID,Fname,Mname from Customer;", con);
MySqlDataReader v1 = view.ExecuteReader();
while (v1.Read()) {
for (int i = 0; i < v1.FieldCount; i++){
result.Add(v1["Cust_ID"].ToString());
[Code] .....
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Feb 9, 2014
How to pull system information and compare it's results with a predefined list.
I know the second part, how to pull system information. Like what CPU/GPU/Motherboard the system that the program is run on has.
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Oct 6, 2012
I want to display the content of my database in list view. The table has 5 columns however when I tried this code
string view = "Select * from cust_infor";
SqlCommand cmd = new SqlCommand(view,FL.clsconnection.opencon());
SqlDataReader dr = cmd.ExecuteReader();
listView1.Items.Clear();
while (dr.Read()) {
listView1.Items.Add(dr[0].ToString()).SubItems.Add(dr[1].ToString());
}
It limits the display to 2 columns. List view will only show the first 2 columns. The code above won't let me add more indexes or subitems. Only up to 2 columns.
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Mar 30, 2013
I am trying to assign a list of values to a vector:
vector<string> words;
words[] = {"one", "two", "three"};
This does not work. How can I accomplish it?
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Apr 20, 2014
is there any way to copy an entire list to a vector? would make my life much easier
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Jan 16, 2015
vector<int> vec1 {2, 4, 6, 8, 10, 12, 14, 16, 18, 20};
This code worked perfectly fine in Xcode earlier today, but when I got home on visual studio 2012 express it is having an error. It's saying that the local function definitions are illegal and has a red mark under the '{' only?
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Dec 14, 2014
How can I write my own container which has properties of both vector and list.
E.g. I can access elements directly using [] operator like vector and behave like list in terms of memory (means we don't have to shift elements if we want to insert in between like list)....
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Aug 26, 2013
I was assigned to print a linked list but as a vector of char (I cannot use the normal string type) , this is what I have:
char* List::asString(){
Node* ite = new Node();
ite= first;//ite is like an iterator of the list
for(int i=0; i<sizeOfList; ++i){//sizeOfList is the total of node of the list
[Code] ....
But when I print that, I get a bunch of weird symbols...
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Oct 6, 2013
I am making a simple program that is suppose to make a list of champions and their items from the game League of Legends. I am stuck on making a vector of the class so each slot within the vector would hold each champion and its data. This is what I got:
Champion_Info.h
#ifndef CHAMPION_INFO_H_INCLUDED
#define CHAMPION_INFO_H_INCLUDED
#include <vector>
#include <string>
using namespace std;
class Champ_Info
[Code] ....
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Mar 19, 2014
I create a list of vectors (a vector of n vectors of m elements).
std::vector <std::vector <int> > vsFA (n, std::vector<int>(n));
How I assign values? I try below, but not worked
void armazenaFA( std::vector <int> &vFA) // this function only knows about vFA
{ vsFA[n] [m]= simTime().dbl();
OR
vsFA[n].push_back(simTime().dbl());
}
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Feb 9, 2015
How to output vector contents using the push_back function. My program reads in values just fine, but it does not output anything and I've been stuck on why.
here is my code:
#include <iostream>
#include <array>
#include <vector>
using namespace std;
int duplicate( vector < int > &vector1, const int value, const int counter)
[Code].....
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Jun 7, 2012
I have a cpp app that reads in a number of files and writes revised output. The app doesn't seem to be able to open a file with a ' in the file name, such as,
N,N'-dimethylethylenediamine.mol
This is the function that opens the file :
Code:
// opens mol file, reads in rows to string vector and returns vector
vector<string> get_mol_file(string& filePath) {
vector<string> mol_file;
string new_mol_line;
// create an input stream and open the mol file
ifstream read_mol_input;
read_mol_input.open( filePath.c_str() );
[Code] ....
The path to the file is passed as a cpp string and the c version is used to open the file. Do I need to handle this as a special case? It is possible that there could be " as well, parenthesis, etc.
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May 13, 2013
I need to create a class vector as a template and define operations on vectors.
And this is what I made.
#include<iostream>
using namespace std;
template<class T>
[Code].....
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Mar 26, 2013
Lets say that I have a vector of vector of integers. <1,2,3,4> , <5,6,7,8>, <10,11,12,13>
How do I make a function that creates vector of vector of every different integers?
<1,5,10> , <1,5,11>, <1,5,12>, <1,5,13>
<1,6,10> , <1,6,11>, <1,6,12>, <1,6,13>
<1,7,10> , <1,7,11>, <1,7,12>, <1,7,13>
<1,8,10>, <1,8,11>, <1,8,12>, <1,8, 13>
<2,5,10>, <2,5,11>, <2,5,12>, <2,5,13>
and so on...
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Jul 5, 2013
I have asked a related question before, and it was resolved successfully. In the past, when I wanted to use std::max_element in order to find the maximum element (or even sort by using std::sort) of a vector of structures according to one of the members of the structure, all I had to do was to insert a specially designed comparison function as the third argument of the function std::max::element. But the latter comparison function naturally accepts two arguments internally.
For instance, here is a test program that successfully finds the maximum according to just one member of the structure:
Code:
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
[Code] ....
And the output was this, as expected:
Maximum element S.a of vector<S> vec is at: 9
[I]max element of vec.a between slot 3 and slot 6 is: 6, and its index is: 6 vec[6].a = 6
[I]max element of vec.a between slot 4 and slot 7 is: 7, and its index is: 7 vec[7].a = 7
[I]max element of vec.a between slot 5 and slot 8 is: 8, and its index is: 8 vec[8].a = 8
[I]max element of vec.a between slot 6 and slot 9 is: 9, and its index is: 9 vec[9].a = 9
However, I now need to search and find an element of vector<myStruct> according to just one member of myStruct, instead of finding the maximum or sorting as before. This presents a problem because the function std::find does not accept such a comparison function as its third argument.
This was the description of the std::find function that I found: find - C++ Reference
Code:
template <class InputIterator, class T> InputIterator find (InputIterator first, InputIterator last, const T& val);
I could also find another function called std::find_if, but this only accepts a unary predicate like this: find_if - C++ Reference
Code:
template <class InputIterator, class UnaryPredicate> InputIterator find_if (InputIterator first, InputIterator last, UnaryPredicate pred);
And once again this is either inadequate of I don't see how to use it directly, because for the third argument I would like to insert a function that takes two arguments with a syntax like this:
Code:
int x=7;
std::vector<S>::iterator result;
result = std::find(vec.begin(), vec.end(), []( const (int x, const S & S_1) { return ( x == S_1.a ) ; } ) ;
Is there another std function that I can use to make search and find an element according to just one member of myStruct?
Or perhaps there is a clever way to pass two arguments to the unary predicate.
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Mar 31, 2014
I am trying to print a matrix solution that I've stored in a vector of doubles. The original matrix was stored in a vector of vector of doubles. I want to print to the screen and an output file. Right now it just prints to screen column-style and the output file is horizontal-style. I tried to change the solution from vector of doubles to a vector of vector of doubles like the original matrix but when I run my code it crashes. Here is what I am referring to:
void readMatrix(vector<vector<double>> &matrix, vector<double> &b, int &N, string input) {
ifstream in(input);
in >> N;
matrix.resize(N);
b.resize(N);
[Code] ....
However when I change my printResult function to this (I removed the string argument because I just want to get it working to the screen first):
void printResult(vector<vector<double>> &sol, const int N) {
//ofstream out(output);
//int j;
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++){
[Code] ....
The program crashes. Am I even printing the matrix correctly?
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Mar 30, 2013
I want to have it so that when i ask for the person witch item they want to drop on the ground it goes into another vector that i can pick back up the item if they want it back and erase when they walk away.
#include "stdafx.h"
#include <iostream>
#include <vector>
#include <string>
#include <fstream>
#include <cmath>
using namespace std;
struct InventoryItem
[Code] ....
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Mar 24, 2012
Code:
#include <iostream>
#include <istream>
#include <fstream>
#include <vector>
[Code]....
Why is it reading in nothing for the arrays, and also making the size of the total thing the total number of numbers? It should have a size of 2, not 5.
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Jun 21, 2012
I am trying to copy vector to vector as follow:
Code:
std::vector<unsigned char> vec1;
//insert some values into vec1
std::vector<unsigned char> vec2;
Now I want to to copy 2 bytes from vec1 starting at index 5., why do i need to know how many bytes from the end of vec1?? can't i just specify how many bytes i want to copy from starting index?
std::copy(vec1.begin()+5, vec1.end()-??, vec2.begin());
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Nov 18, 2014
#include <iostream>
#include <string>
using namespace std;
[Code].....
This is my code, when my pintrials = 0, my system cannot terminate but go through the option menu below.
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Nov 7, 2013
So, as far as I can tell, this code should run a system command from the C++ program:
system("ping 192.168.1.2 /t /l 32768");
However, I just keep getting a "system Was not declared in this scope" error message. Is there something wrong with this?
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