I am running some simulation, in which i need to control the iterator of a multimap, like
multimap<double, int> mapp;
......
int n=6;
for(int i=0; i<5; i++) {
for(auto it = mapp.begin()+i*n; it!=mapp.begin()+(i+1)*n; it++) {
......
However this way of controlling is not possible for multimap. Why and how the make it work? Do I need to overload the operator +?
I have created a multimap for my road points. The key refers to the road number and the values are vec3 points that make up the road.
I am trying to iterate through the values of each key point and create a road segment at each point on the road (except the last), adjust the values to be on the road points and then store them in a std::vector.
The RoadSegment constructor creates 6 vec3 points and pushes them onto a std::vector.
I have a segmentation fault in the line marked in bold
[for(mapIt = it.first; mapIt != it.second; ++mapIt)]
When i take out the lines creating the new objects and pushing them onto the std::vector it works fine.
std::vector<glm::vec3>::iterator SegIt;
for(int i = 0; i < m_genRoads->getKeyValueData().size(); i++)
{
int numberDesired = m_genRoads->getMultimapData().count(i) - 1;
[Code]...
I have a multimap with over 300k entries defined like so: std::multimap<std::string, std::string> filedata;
Using the following code and std::multimap::equal_range, I am able to successfully search for a word in the multimap and get needed data:
// Data with strings.
data = std::vector<std::string>();
// Get iterators to matched pairs.
std::pair <std::multimap<std::string, std::string>::iterator, std::multimap<std::string, std::string>::iterator> dat = filedata.equal_range(word);
// Go through each matched pair and get needed info.
for (std::multimap<std::string, std::string>::iterator iter = dat.first; iter != dat.second; iter++) {
data.push_back(iter->second);
}
Now, I would like to search the multimap using regular expressions (EX: std::regex("[a-z][a-e]h")). What is the fastest way to do this? Example code may look like:
std::pair <std::multimap<std::string, std::string>::iterator, std::multimap<std::string, std::string>::iterator> dat = filedata.equal_range_with_regex(std::regex("" + word + ""));. Pseudo-code / algorithms will be enough.
I understand multimaps are key ordered. I have no problems with ints but when I put my char arrays in they are not alphabetically ordered. I must use char array and not <string>. Is it possible to alphabetically order them with char*
39 int c;
40 User *user;
41 char nameH[200];
42 char line[200];
43 int ageH;
44 double wH;
[code]....
I have an assignment to create a grading system using multimap. It's not completed yet at the moment but whenever i try to compile it tells me "no match for 'operator[]' in lines 56,57,etc. I
#include <iostream>
#include <string>
#include <map>
using namespace std;
class Student {
public:
//--- Constructor
Student (int id = 0, double gpa = 0);
[Code]...
What is the correct syntax? I tried something like
Code:
class myclass {
multimap<int, void(*)()> mm_fn;
...
void afunction();
...
void anotherfunction(int anint){
mm_fn.insert(pair<int,void(*)()>(anint,afunction));
}
}
and the compiler does not like it.
I have researched quite extensively, experimented, and still cannot seem to change the properties of a control on an active winform from a user control.
So I have a user control which populates each dynamically added tab page in a tab control.
I have a textbox in the user control which I would like to type in, capture the text_change event, and change the text of the label in the winform.
How do I bind a DATE column in a DataGridView Control to a DatePicker control (using C#)? I already have the DataGridView control bound to a database stored procedure which takes a DATE value as a parameter and selects joining table based on the results.
View 7 Replies View RelatedHow would i write a functor for this code. The code is written to read data from a file and store in a multimap.
The data has numbered lines. E.g.:
1 This is a string
2 This is a string too
So the aim is to store each word in the line with the number and then to enter a word to search for the line numbers it appears on. I do not know how to go about and write a functor
#include<iostream>
#include<sstream>
#include<fstream>
#include<cstdlib>
#include<map>
using namespace std;
int main() {
multimap<int, string>myMap;
[Code] ....
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?
I have this class with template:
template<template<class, class> class ContainerType>
class Movie {
public:
typedef ContainerType<Actor*, std::allocator<Actor*> > Container;
and i have a member func to find actor in movie according to actor id:
const Actor* findActor(int id) const {
typename Container::iterator it;
Actor* p(NULL);
it=actors.begin();
std::for_each(it,actors.end(),(*it)->getId()==id?p=*it:0);
if (p==*actors.end()) return NULL;
return p;
}
I receive error that no match for operator= in it.
How to declare correct iterator ?the type of actors is Container..
Why this code works
Elenco e1;
e1.add(Persona("a","b"));
e1.add(Persona("c","d"));
e1.add(Persona("e","f"));
e1.add(Persona("e","f"));
e1.remove(2); //list of 4 elements
but this not work?
Elenco e1;
e1.add(Persona("a","b"));
e1.add(Persona("c","d"));
e1.add(Persona("e","f"));
e1.remove(2); //list of 3 elements
This is remove method:
Persona Elenco:: remove(int pos){
list<Persona> ::iterator iter=l.begin();
for(int i=0 ;i<pos;i++){
iter++;
}
return *(l.erase(iter)); //erase ritorna un iterator
}
Here's a few parts of a program I'm working at. It does compile, and it does work as expected. Anyway Eclipse Kepler marks one line as a bug with the remark Field 'befehl' could not be resolved. The bug sign didn't show up when both classes were in one file.
ScriptInterpreter maintains and processes a vector of Objects, initialised with example data. An iterator of the vector keeps track of the current position while various methods process the data. I've copied the relevant lines only.
I can live with a few wrongly bug-marked lines in Eclipse. What I don't want is any hidden errors that express at some time later.
Is there anything wrong with the code? Anything that's not recommended and compiles anyway? Is anything c++11-specific about the questionable line?
AtomicCommand.h
class AtomicCommand {
public:
int befehl;
[Code] .....
Note that line 9 has a bug sign, too. Eclipse doesn't recognise all my c++11 code.
I can't seem to make the STL iterator class work how I need it to.I am implementing a multi list graph and I need to iterate through my STL list of Vertex pointer objects. I keep getting the error:
Error 1 error C2679: binary '=' : no operator found which takes a right-hand operand of type 'std::_List_iterator<_Mylist>' (or there is no acceptable conversion) and the same for != for my terminating condition.
template <typename V, typename E>
void Graph<V, E>::InsertEdge(V from, V to, E edge) {
list<Vertex<V>*>::iterator iter;
for(iter = m_Vertices.begin(); iter != m_Vertices.end(); ++iter)
[code].....
I just figured out that some std functions (for example: copy) need the resource and target objects have iterators to work. Otherwise, the compiler rejects. In case of two arrays, declared as:
double myA[100] = {};
array<double, 100> myB = {};
myA[0] is like a pointer, myB.begin() an iterator, if I do not make any mistake. So, what is exactly the difference between the pointer and the iterator here? They all give the access to elements.
If I need the target of copy to be an array like myA which cannot give an iterator, is there a way to make the command "copy" work for it?
I want to get the iterator position after to use find if:
std::list<Texture*>::iterator result = find_if(
texturelist.begin(),
texturelist.end(),
std::bind2nd<CompareTEX>(CompareTEX(),n_tex));
if (result != texturelist.end()) {
return // position result
}
I am receiving the error: Vector Iterator not incrementable. However, when erasing I'm already re-setting 'it' and pre-incrementing at the end of the while-clause.what's wrong?
vector<st>::iterator it = map[0][0].begin();
while(it != map[0][0].end()) {
if((*it).val == 5) {
[Code] .....
We were given a task to use lists and iterators. We were supposed to make them from scratch. I'm done with that. The problems that I'm having are as following:
1. I'm not able to access the list made of Course datatype which is present in each Student instance. Does this mean I need to make an iterator for that course list inside the student class?
2. Similarly since I don't have direct access to The course list so I added the course into the Student list through the student objects not through the iterator. How can I do it through the iterator?
3. Printing of a particular student and his courses is not happening as my iterator made for student only prints out the students, not the courses present in their courselist. How to do that?
Here's the code
#include <iostream>
#include <string>
using namespace std;
const int ILLEGAL_SIZE = 1;
const int OUT_OF_MEMORY = 2;
const int NO_SPACE = 3;
const int ILLEGAL_INDEX = 4;
[Code] .....
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?
I have a list and a vector, for example like
list<int> mylist = {1, 1, 1, 0, 0, 1, 0, 0}
vector<int> myvec;
I want to create an efficient algorithm to erase all element of value "1", and give these elements to a vector. My code (not efficient) is as follows
for(auto it = mylist.begin(); it != mylist.end(); it++) {
if(*it == 1) {
myvec.push_back(*it);
it = mylist.erase(it);
if(it != mylist.begin())
it--;
}
}
I defined the following function to find out the iterator of a certain value in the vector. I defined it as such so if the value exist in the vector then return a iterator of it, if not then return a pointer pointing to nonsense.:
vector<tIndex_t>::iterator unlabelTit(const tIndex_t index) {
for(vector<tIndex_t>::iterator it=unlabelT.begin(); it<unlabelT.end(); it++) {
if(index==*it) return it;
} return NULL;
}
But looks this one is not accepted by compiler, saying I cannot do this kind of comparison like:
unlabelTit(i)!=NULL;
so I just delete the return NULL; and then the compiler giving me warning about no return statement before }.
a pointer pointing to nonsense? how to do that?
I'm working on a program where I have a vector full of <myClassType> structs.
I'm trying to insert items into a vector, searching first through the vector to make sure the value isn't already in the vector before inserting it. The "find" function isn't working properly.
I keep getting C2678 "binary '==': no operator found which takes a left-hand operand of type "myClassType" or there is no conversion errors in Visual Studio 2010.
I know it's something having to do with the find function and my iterators, but I can't, for the life of me, figure out what it is.
I've tried switching to const_iterators, but I get the same error message.
void foo::insert(const myClassType& en) {
vector<myClassType>::iterator it;
vector<myClassType>::iterator it1;
it = find(Table.begin(), Table.end(), en.memberOne);
[Code] .....
I'm trying to make a function to show the content of maps as follows:
template<typename A, typename B>
void show_map(const std::map<A,B> &src) {
for( std::map<A,B>::iterator it=src.begin(); it!=src.end(); ++it ) {
cout << it->first << " ____ " << it->second << endl;
}
};
However, I got this error in the 'for' line: "error: expected ‘;’ before ‘it’" (and then errors that it is not declared, etc). I'm sure that there is no missing ; in other functions. If you try to write a random line before that you get no error there for example, always in the for.
It is there something that you need to do with iterators when you declare generic datatypes?
I got the core dump file so I know exactly which line it crashes. Below are some of the information:
OS: Red Hat Enterprise 5.8
Example snippets of when the crash happen:
Code:
typedef map<int, MyClassObj> MyMapT;
.
.
void someFunction( MyMapT& inMap )
{
for ( MyMapT::iterator iter=inMap.begin(); iter!=inMap.end(); ++iter )
{
.
.
}
}
Using GDB, I am able to find out that it crashes at the "++iter" as the .h file indicate it was a "++" operation for the iterator. Tracing up the stack frame it indicate it crash during the copy constructor of some "__rb_tree_node". I did some Googling and it seems that is some Red-Black tree implementation for the map. Honestly I do not quite understand the Red-Black tree and I believe STL map is a very very well tested container, so the problem must lie in my code so that I can look out for it.
Code:
it = m_CoopTable->m_SparseMap.find(s);
if (it != NULL) //Error
{
return false;
}
This gives me compile-time error. it is an iterator to a hash_map
In order to parse mathematical expressions I am trying regular expressions and a recursive algorithm, but I have a problem with the four basic operations: +, -, *, /.
Trying to analyze a string like "a+(b+c)", if I use the pattern for a sum "(.+)+(.+)" the program matches it recognizing as subpatterns: "a+(b" and "c". How could I achieve the program to try also the other possibility?
I think that it would be great something like an regex_iterator which worked with regex_match instead of regex_search. I mean, an iterator that iterates over all the possible ways to match a given regular expression and a given string. This way I could loop through all these possibilities until the two subpatterns produced were correct mathematical expressions.