C :: Storing Key - Value Pairs
Mar 26, 2013
I have a project to do in C and coming form Java I miss all the included features that are missing from C! I need to be able to store key value pairs in an quick and memory efficient manner. I've looked up using hash maps but I'm very new to C so don't really understand even the basic ones. I've looked at using a multi-dimensional array as I'm more comfortable with arrays but I'm unsure if that would count as a memory efficient and quick method?
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Dec 15, 2014
I need numbers next to each other to be sorted (in increasing order).On the CPU I'd do something like this:
for(int i=0; i < length; i+=2) {
if(a[i]>a[i+1]) {
switch places...
}
}
But how would I do this using parallel_for_each (C++AMP) ? I need this for some algorithm that works with very long arrays and I think GPU would do this faster than CPU (even if I use all threads).
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Jun 19, 2014
I am attempting to combine two vectors into a vector of pairs. I want to be able to alter the first and second of each pair and have those alterations reflected in the original vectors. I thought the following code might work but get compilation errors about a lack of viable overload for "=" for the line with the call to std::transform:
void f()
{
std::vector<int> a = {1,2,3,4,5};
std::vector<int> b = {6,7,8,9,0};
[Code].....
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Dec 10, 2013
Alexandra has some distinct integer numbers a1,a2...an.
Count number of pairs (i,j) such that:
1≤ i ≤ n
1≤ j ≤ n
ai < aj
Input
The first line of the input contains an integer T denoting the number of test cases. The description of T test cases follows. The first line of each test case contains a single integer n denoting the number of numbers Alexandra has. The second line contains n space-separated distinct integers a1, a2, ..., an denoting these numbers.
Output
For each test case, output a single line containing number of pairs for corresponding test case.
Constraints
1 ≤ T ≤ 4
1 ≤ n ≤ 100000
0 ≤ ai ≤ 109
All the ai are distinct
Example
2
2
2 1
3
3 1 2
Output:
1
3
Explanation
Case 1: Only one such pair: (2,1)
Case 2: 3 possible pairs: (2,1), (2,3), (3,1)
as I understand the problem is just counting how many Ai's are 1 <= Ai <= N and then apply ((R*(R-1))/2), R is the count of valid Ai's
My actual code is
#include <stdio.h>
using namespace std;
#ifndef ONLINE_JUDGE
#define getNumber getchar()
#define getString getchar()
[Code] ....
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May 19, 2014
I am working with cart algorithm and i have the following problem,i need to try all possible splits of n values in order to determine the best.
So lets say i have 3 values("low","medium",high) then the possible splits(pairs) would be:
(assuming low=0,medium=1,high=2)
0,1-2 low,medium-high
1,0-2 medium,low-high
2,1-0 high,medium-low
For 4 values(a,b,c,d) it would be:
ab,cd
ac,bd
ad,bc
abc,d
adb,c
adc,b
bcd,a
Problem is i dont know n so the solution must be recursive. The possible splits are 2^(n-1)-1. I am really stuck and most of the code is complete for cart and i really don't want to restrict it to binary values.
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May 16, 2013
Say I have a vector of objects and I want to return an object based on a pair of strings. The strings can be in either order Ie; A B==B A.
In general, what do you think is the best way to do this?
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Feb 28, 2013
coming from Java, my experience with the Classes in C++ is quite limited.
Thats why I am having trouble converting the following (simple!) Java-Program.
Most examples with linked lists I found on the web describe how to implement the LinkedList class itself. But my problem is different: I want to use such a Class (I have a LinkedList class available on my system which is presumably OK).
Code: package main;
import java.util.ArrayList;
public class Main {
public static void main(String[] args) {
BoxList<String> sl = new BoxList<String>(
new ArrayList<ABox<String>>());
sl.getList().add(
new BoxPair2<String>(new BoxPair2<String>(
[code].....
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Jan 18, 2015
I'm trying to write a simple program that finds the minimum difference between two pairs of integers in a list/array. Of no surprise, it not work the first time I ran it so naturally i chucked in a whole bunch of print statements to debug
I encountered a peculiar error that is really stumping me.
#include <iostream>
using namespace std;
int closest_pair(int arr[]) {
int i=0;
int j=0;
int size=0;
int min=0;
[Code] .....
OUTPUT:
size_main: 20
arr_main: 80
arr[0]_main: 4
size: 2
arr: 8
arr[0]: 4
0: 34
1: -12
2: 18
3: 61
19: 75
closest_pair: 0
I'm printing the size of the array in main and inside the function...and inside the function its giving me a size = 2 which is incorrect though the size printed in main is correct (size = 20). I further narrowed down the discrepancy to this statement: sizeof(arr)
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May 21, 2012
I have been writing a program to generate pairs of RSA keys using small prime numbers. I have been using mpz_invert() to get a value for d for the private key. On small prime numbers it calculates the correct value, but on larger primes it calculates incorrect values.
I'm assuming there must be an upper limit to the values the mpz_invert() function can handle? If so, what is this limit to avoid erroneous values?
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Feb 5, 2014
So i'm creating bank system. Where I have function that reads the text file (balance), and I make a deposit, which adds what was in the balance = deposit + balance.
But this is what is happening. In my text file i have number 10. Function balance works fine and reads 10 from the text file.
When I make a deposit add a value to the balance, if i add 7, the new balance is 17. And i check the text file shows me is 17. Which is correct.
The problem is here. If i make another deposit, without closing the program, for example i add 5 to the balance, the new balance should be 22 = 17(balance) + 5(deposit), because 17 was store on the text file and it was the balance that was store on the text file on the last time. But it shows me 15, it adds the balance that the program first started which was 10(balance) + 5(deposit), but should had had be 17 + 5.
When I close the program the value on the text file, is 15, that was the last sum that i did.
int main()
{
double balance = 0;
balance = currentBalance(balance);
menu(balance);
[Code].....
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Mar 29, 2014
I am doing this program where I analyze colors in a ppm file. Now I am having a hard time storing the data into arrays in this order...
P3
600 339
255
44 5 8
44 5 8
43 4 7
42 3 6
42 3 4
44 5 6
...
So far i tried using fscanf()
Code:
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <stdbool.h>
#define DEBUG true
#define CHECK true
[Code] ....
I then realized that the order that the second method gave me will make it very hard for me to calculate the RGBs. Because they will be calculated like wise..
P3
600 339
255
44 5 8 = sum
44 5 8 = sum
43 4 7 = sum
42 3 6 = sum
42 3 4 = sum
44 5 6 = sum
...
but that isn't the issue right now..
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Dec 9, 2014
I wanted to find all the prime until a specified limit in C. I use the Sieve of Eratosthenes. But when I define the limit to anything more than a 7 digit number the program terminates.
Code:
#include<stdio.h>
#define limit 1000000000
int main(void)
{
unsigned long long int i,j;
int primes[limit] = {0};
//int count =0;
for(i=2;i<limit;i++)
}
[code]....
I believe that this might be because the size cannot be declared array cannot be more than the a 7 digit number. I think so. how to store a 10 digit number in C?And can't unsigned long long hold a 10 digit?
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Mar 27, 2013
I am having trouble storing strings into an array. Basically I have a console program where it has an option. This is just an example;
Code:
char name[max];
char listofnames[maxname];
int counter;
....
printf("Add names
");
And how can I print it?
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May 4, 2013
So i have a program with the structure
Code:
char record[20];
typedef struct{
int id;
char title[20];
char subject[20];
char faculty [20];
int level;
char fname[25];
}report;
int recno,i;
report list[100];
I need to store the hundred records into a file. What are the functions and elements i should use/introduce.
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May 2, 2013
How do I go about storing info to an array of class?I need to do something like this:
info[count] = ReadNameRating(n, r);
Where info is an array of my own class and ReadNameRating reads the name and rating which is two of the variables handled by that class.
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Oct 17, 2013
I have a file that can range from 100 rows to 10000+ that is comma delimited with 8 columns. The first 32 rows (also comma delimited) will always be ignored (geographical header information). I will be wanting the data from column2 and column3.
For this I believe I would need (2) For Loops as such:
for(i=0;i<2;++i) {
getline("do something here");
}
and
for (i=0;i<3;++i) {
getline("do something here")
}
Also would using a vector or array with dynamic storage be the better way to tackle this problem? Where to start from after accessing the file.
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Mar 27, 2013
Is it possible to store data to CPU memory, if so how much memory can I store and how? Say I wanted to store an array, about 6MB in size?
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Sep 27, 2013
I have a base class Building. Then come its children classes - Commercial Building and Residential Building. The third level is composed of Apartment and House classes, both inherit from Residential Building.
I need to create an array of 20 elements that will store info about all these different types of buildings(Commercial Building,Residential Building,Apartment, House). How should I proceed?
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Oct 31, 2014
I have two classes, Parent and Child, where Parent contains a vector that is used to store instances of Child. When I create an instance of Parent, three instances of Child are also created in Parent's constructor and stored in the vector. I understand that push_back() creates a shallow copy of each Child instance and that Child's destructor is called each time the loop (inside Parent's constructor) iterates. The problem is that because Child's destructor is called each time the local variable child goes out of scope, the memory previously allocated in Child's constructor is destroyed and when Child's destructor is called again later on in the program to get rid of the copy stored in vector, the program crashes. I can fix this by overriding the default copy function or by storing pointers to objects instead of copies of objects. I don't really need to use vectors in this case since I always have three children in one parent but I'm doing this as a learning exercise and would prefer to use vectors.
#include <iostream>
#include <vector>
class Child {
public:
Child() {
std::cout << "child constructor called" << std::endl;
[Code] .....
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Apr 12, 2013
I am trying to store the Title, Artist, and date published of a list of CD's. I can't seem to be able to get it to print the list or not sure if it is actually storing it. This is what i have so far.
#include <iostream>
#include <fstream>
#include <cstdlib>
#include <string>
using namespace std;
int main() {
char names[5][100];
[code]....
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Jul 13, 2014
I'm having trouble storing a string in a vector.
I keep getting the errors in lines 51-54: no suitable constructor exist to convert from
#include <iostream>
#include <string>
#include <vector>
#include "Movie.h"
using namespace std;
vector <string> movieActors;
void promptForMovie(Movie & myMovie);
[code]....
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May 1, 2014
I have a list of integers that i wish to store in some kind of array. However i do not know how many integers are needed to be stored each time i run my program so i therefore cannot define a size for my array.
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Feb 25, 2014
I'm am trying to get info from a file and put it into three arrays but it isn't working.
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
void sort(ifstream& infile){
[code]....
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Jan 22, 2015
storing int=9000000000; gives me another number. how can i store the value?my bad int number=9000000000;
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Apr 3, 2015
I have an application which needs to connect to a database. It runs in the background so there is no user input. I therefore need to store the connection string. I want to encrypt the connection details and then store the encrypted information. My thinking is I would read the encrypted details, from wherever I store them, unencrypt them and then connect to my database.
I've done a bit of reading on this and the SHA1CryptoServiceProvider method seems like an option but it appears that this cannot be unencrypted.
So how can I use this encrypted information?
Or is there another method?
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Jan 10, 2013
I'm trying out the code below; it runs and produces the output I'd expect, but could it lead to undefined behavior?
To test with, I show the key and wait for user input; if the input doesn't match the value, the iterator is stored in the vector.
map<string, string> test;
map<string, string>::iterator it;
vector<map<string, string>::iterator> bad_input;
string input;
test["key 1"] = "value 1";
[Code] ....
I am also interested in knowing if I can use an iterator to walk through the vector? I tried
vector<map<string, string>::iterator>::iterator v_it;
for(v_it = bad_input.begin(); v_it != bad_input.end(); ++v_it)
cout << v_it-> ??
However, I couldn't figure out how to access "first" and "second" using this method. Is it possible to do so?
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