C++ :: Std List - How To Get Value Of Element 2 Minus Element 1
Aug 23, 2012
I have an std list of type double.. and the list is always guaranteed to have just 2 elements. I need to get the value of element 2 minus element 1. What is the least amount of code to accomplish that?
I tried this:
Code:
list<double> dList;
dList.push_back(1.0);
dList.push_back(2.0);
list<double>::iterator iter = dList.begin();
list<double>::iterator iter2 = dList.end();
double result = *iter2 - *iter;
But this code does not work. Why not?
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Mar 10, 2014
So I have linked list and function which deletes element if next element is bigger, so my code is working but its not working with first element, in the comment I have wrote code which I would code for checking that first element, but when ever I check it is blowing up all program.
#include <iostream>
using namespace std;
struct llist {
int x;
llist *next;
[Code] .....
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Feb 23, 2013
I have a global list that contains smaller lists of char arrays. I have an issue where when I'm reading back the inner lists the last element of one list seems to point to first element of the next.
So my data looks like the below (values separated by commas with the pairs separated by tabs. The last pair in a line is the same as the first). When I read the first list back instead of seeing "456.678,678.98" as the last element in the list. I see "435.67,234.98" twice: at the end of the first list and start of the other. I have debugged when the list is populated and can see the correct values going in so I can't figure what's happening.
456.678,678.98 123.45,345.56 256.67,789.98 456.678,678.98
435.67,234.98 123.65,342.56 987.78,678.34 435.67,234.98
Code to fill the list:
obstacle_list = op_prg_list_create();
while (fgets(line, sizeof(line), obstaclePositions_traj_file) ) {
token = strtok(line, "
"); //Pull the string apart into tokens using the
input = op_prg_list_create();
[Code] ....
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Dec 31, 2014
Code:
// Write a function called insertEntry() to insert a new entry into a linked list.
Have the procedure take as arguments a pointer to the list entry to be inserted (of type struct entry as defined in this chapter), and a pointer to an element in the list after which the new entry is to be inserted.
// The function dveloped in exercise 2 only inserts an element after an existing element in the list, thereby prenting you from inserting a new entry at the front of the list.
(Hint: Think about setting up a special structure to point to the beginning of the list.)
#include <stdio.h
struct entry1 {
int value;
struct entry1 *next;
};
[code]...
This is a working version of the exercise, but I don't think I'm doing what's asked. I was able to add an element to the beginning of the list using an if statement, not creating a special structure that points to the beginning of the list. How would I go about creating a special structure that points to the beginning of the list to add a new element at the beginning of the list?
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Mar 27, 2013
How can I remove an element in a list when I have only an iterator that points to the object I want to remove. Is there a build in command? remove() takes an object reference as its argument. Is it possible to convert the iterator into a pointer type so it can be deferenced and passed to remove?
This is the code I am working on:
//player.cpp
void Player::CheckCollectableCollisions(std::list<Collectable>& c) {
std::list<Collectable>::iterator i = c.begin();
while(i != c.end()) {
if (Collider::CheckCollision(pNodes_.front().getLocation(), i->getLocation()))
[Code] .....
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Nov 26, 2014
Here's my list code:
Color.FromArgb(alfa, 0, 255, 255),
Color.FromArgb(alfa, 0, 255, 0),
Color.FromArgb(alfa, 64, 255, 0),
Color.FromArgb(alfa, 128, 255, 0),
Color.FromArgb(alfa, 192, 255, 0),
Color.FromArgb(alfa, 255, 255, 0),
Color.FromArgb(alfa, 255, 192, 0),
Color.FromArgb(alfa, 255, 128, 0),
Color.FromArgb(alfa, 255, 64, 0),
Color.FromArgb(alfa, 255, 0, 0)
How can I get a specific element value from that list?
For example:
if(true)
{
//get "192" from Color.FromArgb(alfa, 255, 192, 0)
}
I don't see the "Edit" option and I've noticed a slight error in the previous post.There should be, obviously, [code]if(true)
{
//get "192" from Color.FromArgb(alfa, 255, 192, 0)
}
I was missing the closing tag.
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Jun 6, 2013
This code is from a example in Jumping Into C++ and I understand the example. But it is a practice problem that is to write a program to remove an element from a linked list; the remove function should take just the element to be removed.
Code: #include <iostream>
using namespace std;
struct EnemySpaceShip {
int x_coordinate;
int y_coordinate;
[Code]...
If I got this right I will create a pointer that points to the first SHIP (getNewEnemy) and the other one will not be printed out.
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Oct 17, 2014
This is my current code. The code is to remove the element in the list "head" that is "e". The code works if there is only one element in the list but if there are more than 1 element in the list, it doesn't work. The function should return true if there is an element that equals "e" and then it removes it and false if no element equals "e".
bool StringLinkedList::remove(const std::string& e){
StringNode* current = head;
int i = 0;
if (current == NULL)
return false;
[Code] ....
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May 2, 2014
I've got this program that I'm working on. Most of the code is from a video tutorial, but I was editing it to be able to search for an element by name. That's working fine, but suddenly the part of the program that prints out all the elements starts in an infinite loop after I input two elements, and search for one.
Here's what I've got:
[code#include <iostream> usingnamespacestd; struct node { int number; string name; node *next; }; bool isEmpty (node *head); char menu (); void insertAsFirstElement (node *&head, node *&last, int number); void insertSorted(node *&head, node *&last, int number); void remove(node *&head, node *&last); void showList (node *current); void showByName (node *current, string name); bool isEmpty (node *head) { if (head == NULL) { return true; } else { returnfalse; } } char menu () { char choice;
[Code] .....
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Sep 6, 2014
I'm trying to calculate the total price of books contained in a linked list. I've tried getTotal() function in linked list but error: no match for 'operator+=' in 'total += ptr->Node<Book>::info'| occurred. How can I access the price in the node and then calculate the total price.
Here is part of my code :
Book class
class Book {
protected :
int id;
string title;
double price;
string bookStatus;
[code]....
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Nov 11, 2013
I have been trying to implement a way to remove a post from a list of posts implemented with a template doubly linked list. I have thought that the best way to do this might by operator overloading, but I have digressed. I have just thought of using a isEqual that checks equality, but when trying to implement i'm getting weird errors.
This is within my class wall, which is a linked list of wall posts, getPostInfo is within the class WallPost.
bool isEqual(WallPost const & a, WallPost const & b)
{
if(a.getPostInfo() == b.getPostInfo())
return true;
else
return false;
}
I have several instances of the error "void illegal with all types" on line 3. It also is complaining about a not being a arithmetic, unscoped enum, or pointer type. I am assuming that it is because my getPostInfo function is a void.
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Feb 23, 2013
I am trying to write a function to return the first element of a link list queue. I am not real sure how to implement this. I have include a copy of the struct for my Node & queue.
Code:
typedef struct event_Node {
void *data;
double arri_time;
double serv_time;
double depart_time;
double start_o_serv;
[Code]...
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Jan 18, 2014
Code:
struct lista* del(struct lista* p, char* path1) {
char model[MAX2];
int len;
char ch;
printf("Type model.
[Code] ..... t
This function should delete each element in the list which is the same as this one typed by user. There are no errors, but function doesn't work. It deletes something, but not this element which should.
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Sep 7, 2014
I tried to modify staff name with an assignment value of other string but couldn't work it out. I managed to modify it by key in cin >>.
The purpose is that I want to assign string value from other different class to Staff class. An error : no match for 'operator=' in '* updateName = newStaffName' and note: no known conversion for argument 1 from 'std::string {aka std::basic_string<char>}' to 'const Staff&' occurred.
#include <iostream>
using namespace std;
class Staff {
friend ostream& operator << (ostream& os, Staff& m) {
os << "[" << m.ID << ", " << m.fName << "]";
[Code]...
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Jun 23, 2014
I am getting an error with my while loop(feels dumb) when running this code that I am allowed to modify. It is to remove all instances of an element within the list.
The loop is whithin this function:
void arrayListType<elemType>::removeAll(int location)
I have attached both the header file and main function file in .txt format.
void arrayListType<elemType>::removeAll(int location)*
Attached File(s) :
header.txt (12.23K)
main function.txt (2.95K)
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Jun 17, 2013
I'm making my first steps in STL, and I have a few question:
Is there a way to get an iterator to the i'th element in the collection (set or list), instead of just to the end or the begin?
And another question: Let's say I have an iterator, pointing to some element in my collection, and I use erase() (which takes as parameter an iterator that points to the soon-to-be erased element), what happens to that iterator? will it now point to NULL?
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Jun 20, 2013
I have a map as below. MoTopImpl is a class.
Map<MoTopImpl*,os_Reference_protected<MoTopImpl> > map_;
The map is populated as below:
void setMoInMap(MoTopImpl* mo,MoTopImpl* me) {
map_[mo] = me;
}
Now, I want to remove a specific element from this map. I am passing the element to be removed to the remove function as below:
void Asap::removeMoFromMap(MoTopImpl* mo) {
// First solution
if (mo != 0) {
[Code]....
And the function removeMoFromMap is called as below:
MoTopImpl* moTop = getMoTopImpl();
if (moTop != 0)
removeMoFromListMosSuspended(moTop);
But I am able to empty the map by iterating through the complete map as below:
Mapiter<MoTopImpl*,os_Reference_protected<MoTopImpl> > moIter(map_);
for (moIter = map_.first(); moIter; moIter.next()) {
moIter.remove();
}
cout << "Map zise = " << map_.size() << endl; // Prints zero
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Sep 21, 2013
I have a "fairly" large, std::map. Is there a way, to get the key of an element, by position? E.g., something like,
map.at(i).getkey
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Oct 5, 2014
My code has been acting odd. I made a function that layers my art resources but only the last tile of my art resource acts the way it should. My character goes behind and in front of the last tile and gets printed correctly. Strangely its really exclusive to the last tiles I print. What I need is to figure out in step by step order what going on with my code sample below and be able to layer the resources.
Here is a small sample of my main function. This is how I do my rendering.
Code:
Int main (int arc, char* args[]) {
//Move class
Move character;
//Class Tile & Side Tile
Tile *tiles [TOTAL_TILES];
[Code] ......
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Mar 6, 2015
how to compare each element of array with another,defined ? I have tried this,but didn't work.
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
void bill()
[Code].....
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Jan 27, 2013
I want to a C program to delete an element from an array which can use both index method & character method
For example
input : "1 222 333 4444"
output:"1 22 333 4444"
if either index = "4" or character ="2" is entered
It should able to read in/accept any input array of varying length, and the position/index or element in array to be deleted...
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Jan 9, 2015
how to delete an element(s) from an array; suppose I have an array x[10] = {1,2,3,4,5,6,7,8,9,10}, and I want to delete array{5} so that the values of the array become {1,2,3,4,5,7,8,9,10}; how do I go about this? This is not the same as setting the value of array{5} to null; but completely eliminating it so that it does not get printed alongside the other elements of the screen.
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Oct 7, 2013
Lets assume, I use array of 100 the i input 50 element and now i want to find which one is first in array... without using pointer ...
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May 6, 2014
This is a program to get an 10 characters including a-z, A-Z, and _ .
Then this program will cout the text with out _ !
Example:
cin >> sd_fd_e_dd
cout << sdfdedd
# include <iostream>
#inclued<vector>
using namespace std;
char a[10],m;
[Code] ....
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May 13, 2013
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
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Feb 17, 2014
"Write a program in C that finds the element of an array which all the previous are smaller and all the next are bigger than that.If there are more than one print the biggest. If there isn't any print "ERROR" .
EXAMPLE
If the array has 10 elements like this : {2,3,4,6,5,7,8,10,9,8}
The correct answer is 7 , because 2,3,4,6,5 are smaller than 7 and 8,10,9,8 are bigger than 7.
I am working on it for 2 weeks and I can't find a working solution />/>/>
There is the first try :
#include <stdio.h>
#include <stdbool.h>
int s_data[10]={2,3,4,6,5,7,8,10,9,8};
int main() {
int result,i,j,s_len ,tmp1,tmp;
bool GT_PREV,ST_NEXT;
[Code] .....
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