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STL for games, yea or nay?

- by munificent

Every programming language has its standard library of containers, algorithms, and other helpful stuff. With languages like C#, Java, and Python, it's practically inconceivable to use the language without its standard lib. Yet, on many C++ games I've worked on, we either didn't use the STL at all, used a tiny fraction of it, or used our own implementation. It's hard to tell if that was a sound decision for our games, or one simply made out of ignorance of the STL. So... is the STL a good fit or not?

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Making sure unsigned int/long always execute in checked context in C#

- by theburningmonk

Has anyone found it strange that the default context for uint and ulong is unchecked rather than checked considering that they are meant to represent values that can never be negative? So if some code is trying to violate that constraint it seems to me the natural and preferred behaviour would be to throw an exception rather than returning the max value instead (which can easily leave important pieces of data in an invalid state and impossible to revert..). Is there an existing attribute which can be applied to either class/assembly so that it always performs arithmetic operations in a checked context? I was thinking of writing one myself (as an aspect using PostSharp) but would be great if there's one already. Many thanks,

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checkbox checked not appearing as checked in controller

- by user281180

I have the following code in my view <tr><td><%=Html.Hidden("ProjectID["+(count)+"]",item.ProjectID)%><%=item.ProjectName%></td><td><input type="checkbox" name="Name[<%=count%>]" /></td></tr> In my controller, the checkboxes value appear false depsite having been checked in on the web page. how can I correct that?

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VS2008 -> VS2010 leads to cryptic STL errors

- by Jakobud

The following C++ library was successfully compiled in VS2008 http://sourceforge.net/projects/xmlrpcc4win/files/xmlrpcc4win/XmlRpcC4Win1.0.8.zip/download When I open it in VS2010, it goes through the conversion wizard process without any errors. Now, when I attempt to compile it in VS2010, I get some weird STL errors like these: 1>TimXmlRpc.cpp(1018): error C2039: 'back_insert_iterator' : is not a member of 'std' 1>TimXmlRpc.cpp(1018): error C2065: 'back_insert_iterator' : undeclared identifier 1>TimXmlRpc.cpp(1018): error C2275: 'XmlRpcValue::BinaryData' : illegal use of this type as an expression 1>TimXmlRpc.cpp(1018): error C2065: 'ins' : undeclared identifier 1>TimXmlRpc.cpp(1018): error C2039: 'back_inserter' : is not a member of 'std' 1>TimXmlRpc.cpp(1018): error C3861: 'back_inserter': identifier not found 1>TimXmlRpc.cpp(1019): error C2065: 'ins' : undeclared identifier 1>TimXmlRpc.cpp(1031): error C2039: 'back_insert_iterator' : is not a member of 'std' 1>TimXmlRpc.cpp(1031): error C2065: 'back_insert_iterator' : undeclared identifier 1>TimXmlRpc.cpp(1031): error C2275: 'std::vector<_Ty>' : illegal use of this type as an expression 1> with 1> [ 1> _Ty=char 1> ] 1>TimXmlRpc.cpp(1031): error C2065: 'ins' : undeclared identifier 1>TimXmlRpc.cpp(1031): error C2039: 'back_inserter' : is not a member of 'std' 1>TimXmlRpc.cpp(1031): error C3861: 'back_inserter': identifier not found 1>TimXmlRpc.cpp(1032): error C2065: 'ins' : undeclared identifier I'm not sure what to make of some of these. For instance, back_insert_iterator is in fact a member of std, but VS doesn't seem to think it is. How do I fix errors like these? They just don't seem to make much sense so I'm not sure where to begin. Perhaps its something in my project settings? For example, here is line 1018, which gives the std error: std::back_insert_iterator<BinaryData> ins = std::back_inserter(*(u.asBinary)); If anyone could give me some direction I'd appreciate it. I'm new enough to C++ that I'm having a tough time figuring out this one.

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maps, iterators, and complex structs - STL errors

- by Austin Hyde

So, I have two structs: struct coordinate { float x; float y; } struct person { int id; coordinate location; } and a function operating on coordinates: float distance(const coordinate& c1, const coordinate& c2); In my main method, I have the following code: map<int,person> people; // populate people map<int,map<float,int> > distance_map; map<int,person>::iterator it1,it2; for (it1=people.begin(); it1!=people.end(); ++it1) { for (it2=people.begin(); it2!=people.end(); ++it2) { float d = distance(it1->second.location,it2->second.location); distance_map[it1->first][d] = it2->first; } } However, I get the following error upon build: stl_iterator_base_types.h: In instantiation of ‘std::iterator_traits<coordinate>’: stl_iterator_base_types.h:129: error: no type named ‘iterator_category’ in ‘struct coordinate’ stl_iterator_base_types.h:130: error: no type named ‘value_type’ in ‘struct coordinate’ stl_iterator_base_types.h:131: error: no type named ‘difference_type’ in ‘struct coordinate’ stl_iterator_base_types.h:132: error: no type named ‘pointer’ in ‘struct coordinate’ stl_iterator_base_types.h:133: error: no type named ‘reference’ in ‘struct coordinate’ And it blames it on the line: float d = distance(it1->second.location,it2->second.location); Why does the STL complain about my code?

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shared memory STL maps

- by user306963

Hello, I am writing an Apache module in C++. I need to store the common data that all childs need to read as a portion of shared memory. Structure is kind of map of vectors, so I want to use STL map and vectors for it. I have written a shared allocator and a shared manager for the purpose, they work fine for vectors but not for maps, below is the example: typedef vector<CustomersData, SharedAllocator<CustomersData> > CustomerVector; CustomerVector spData; //this one works fine typedef SharedAllocator< pair< const int, CustomerVector > > PairAllocator; typedef map< int, CustomerVector, less<int>, PairAllocator > SharedMap; SharedMap spIndex; //this one doesn't work I get compile time errors when I try to use the second object (spIndex), which are someting like: ../SpatialIndex.h:97: error: '((SpatialIndex*)this)-SpatialIndex::spIndex' does not have class type It looks like the compiler cannot determine a type for SharedMap template type, which is strange in my opinion, it seems to me that all the template parameters have been specified. Can you help? Thanks Benvenuto

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Idiomatic STL: Iterating over a list and inserting elements

- by mkilling

I'm writing an algorithm that iterates over a list of points, calculates the distance between them and inserts additional points if the distance is too great. However I seem to be lacking the proper familiarity with STL to come up with an elegant solution. I'm hoping that I can learn something, so I'll just show you my code. You might have some hints for me. for (std::list<PathPoint>::iterator it = ++points_.begin(); it != points_.end(); it++) { Vector curPos = it->getPosition(); Vector prevPos = (--it)->getPosition(); Vector vecFromPrev = curPos - prevPos; float distance = vecFromPrev.abs(); it++; if (distance > MAX_DISTANCE_BETWEEN_POINTS) { int pointsToInsert = (int)(distance / MAX_DISTANCE_BETWEEN_POINTS); Vector curPos = prevPos; for (int i = 0; i < pointsToInsert; i++) { curPos += vecFromPrev / pointsToInsert; it = points_.insert(it, PathPoint(curPos, false)); it++; } } }

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How to load/save C++ class instance (using STL containers) to disk

- by supert

I have a C++ class representing a hierarchically organised data tree which is very large (~Gb, basically as large as I can get away with in memory). It uses an STL list to store information at each node plus iterators to other nodes. Each node has only one parent, but 0-10 children. Abstracted, it looks something like: struct node { public: node_list_iterator parent; // iterator to a single parent node double node_data_array[X]; map<int,node_list_iterator> children; // iterators to child nodes }; class strategy { private: list<node> tree; // hierarchically linked list of nodes struct some_other_data; public: void build(); // build the tree void save(); // save the tree from disk void load(); // load the tree from disk void use(); // use the tree }; I would like to implement the load() and save() to disk, and it should be fairly fast, however the obvious problems are: I don't know the size in advance; The data contains iterators, which are volatile; My ignorance of C++ is prodigious. Could anyone suggest a pure C++ solution please?

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C++ STL question related to insert iterators and sets

- by rshepherd

#include #include #include #include using namespace std; class MyContainer { public: string value; MyContainer& operator=(const string& s) { this->value = s; return *this; } }; int main() { list<string> strings; strings.push_back("0"); strings.push_back("1"); strings.push_back("2"); set<MyContainer> containers; copy(strings.begin(), strings.end(), inserter(containers, containers.end())); } The preceeding code does not compile. In typical STL style the error output is verbose and difficult to understand. The key part seems to be this... /usr/include/c++/4.4/bits/stl_algobase.h:313: error: no match for ‘operator=’ in ‘__result.std::insert_iterator::operator* [with _Container = std::set, std::allocator ]() = __first.std::_List_iterator::operator* [with _Tp = std::basic_string, std::allocator ]()’ ...which I interpet to mean that the assignment operator needed is not defined. I took a look at the source code for insert_iterator and noted that it has overloaded the assignment operator. The copy algorithm must uses the insert iterators overloaded assignment operator to do its work(?). I guess that because my input iterator is on a container of strings and my output iterator is on a container of MyContainers that the overloaded insert_iterator assignment operator can no longer work. This is my best guess, but I am probably wrong. So, why exactly does this not work and how can I accomplish what I am trying to do?

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C++ STL make_heap and pop_heap not working.

- by Henrique

I need to use a Heap, so i've searched about the STL one, but it doesn't seem to work, i wrote some code to explain what i mean: #include <stdio.h> #include <stdlib.h> #include <vector> #include <algorithm> struct data { int indice; int tamanho; }; bool comparator2(const data* a, const data* b) { return (a->tamanho < b->tamanho); } int main() { std::vector<data*> mesas; data x1, x2, x3, x4, x5; x1.indice = 1; x1.tamanho = 3; x2.indice = 2; x2.tamanho = 5; x3.indice = 3; x3.tamanho = 2; x4.indice = 4; x4.tamanho = 6; x5.indice = 5; x5.tamanho = 4; mesas.push_back(&x1); mesas.push_back(&x2); mesas.push_back(&x3); mesas.push_back(&x4); mesas.push_back(&x5); make_heap(mesas.begin(), mesas.end(), comparator2); for(int i = 0 ; i < 5 ; i++) { data* mesa = mesas.front(); pop_heap(mesas.begin(),mesas.end()); mesas.pop_back(); printf("%d, %d\n", mesa->indice, mesa->tamanho); } return 0; }; and this is what i get: 4, 6 2, 5 1, 3 3, 2 5, 4 So it's not working as a heap, as the maximum element on the vector is not being returned right. Or am i doing something wrong?

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Is it a good idea to create an STL iterator which is noncopyable?

- by BillyONeal

Most of the time, STL iterators are CopyConstructable, because several STL algorithms require this to improve performance, such as std::sort. However, I've been working on a pet project to wrap the FindXFile API (previously asked about), but the problem is it's impossible to implement a copyable iterator around this API. A find handle cannot be duplicated by any means -- DuplicateHandle specifically forbids passing handles to it. And if you just maintain a reference count to the find handle, then a single increment by any copy results in an increment of all copies -- clearly that is not what a copy constructed iterator is supposed to do. Since I can't satisfy the traditional copy constructible requirement for iterators here, is it even worth trying to create an "STL style" iterator? On one hand, creating some other enumeration method is going to not fall into normal STL conventions, but on the other, following STL conventions are going to confuse users of this iterator if they try to CopyConstruct it later. Which is the lesser of two evils?

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What is the right approach when using STL container for median calculation?

- by sharkin

Let's say I need to retrieve the median from a sequence of 1000000 random numeric values. If using anything but STL::list, I have no (built-in) way to sort sequence for median calculation. If using STL::list, I can't randomly access values to retrieve middle (median) of sorted sequence. Is it better to implement sorting myself and go with e.g. STL::vector, or is it better to use STL::list and use STL::list::iterator to for-loop-walk to the median value? The latter seems less overheadish, but also feels more ugly.. Or are there more and better alternatives for me?

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Bewildering SegFault involving STL sort algorithm.

- by just_wes

Hello everybody, I am completely perplexed at a seg fault that I seem to be creating. I have: vector<unsigned int> words; and global variable string input; I define my custom compare function: bool wordncompare(unsigned int f, unsigned int s) { int n = k; while (((f < input.size()) && (s < input.size())) && (input[f] == input[s])) { if ((input[f] == ' ') && (--n == 0)) { return false; } f++; s++; } return true; } When I run the code: sort(words.begin(), words.end()); The program exits smoothly. However, when I run the code: sort(words.begin(), words.end(), wordncompare); I generate a SegFault deep within the STL. The GDB back-trace code looks like this: #0 0x00007ffff7b79893 in std::string::size() const () from /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/libstdc++.so.6 #1 0x0000000000400f3f in wordncompare (f=90, s=0) at text_gen2.cpp:40 #2 0x000000000040188d in std::__unguarded_linear_insert<__gnu_cxx::__normal_iterator<unsigned int*, std::vector<unsigned int, std::allocator<unsigned int> > >, unsigned int, bool (*)(unsigned int, unsigned int)> (__last=..., __val=90, __comp=0x400edc <wordncompare(unsigned int, unsigned int)>) at /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:1735 #3 0x00000000004018df in std::__unguarded_insertion_sort<__gnu_cxx::__normal_iterator<unsigned int*, std::vector<unsigned int, std::allocator<unsigned int> > >, bool (*)(unsigned int, unsigned int)> (__first=..., __last=..., __comp=0x400edc <wordncompare(unsigned int, unsigned int)>) at /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:1812 #4 0x0000000000402562 in std::__final_insertion_sort<__gnu_cxx::__normal_iterator<unsigned int*, std::vector<unsigned int, std::allocator<unsigned int> > >, bool (*)(unsigned int, unsigned int)> (__first=..., __last=..., __comp=0x400edc <wordncompare(unsigned int, unsigned int)>) at /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:1845 #5 0x0000000000402c20 in std::sort<__gnu_cxx::__normal_iterator<unsigned int*, std::vector<unsigned int, std::allocator<unsigned int> > >, bool (*)(unsigned int, unsigned int)> (__first=..., __last=..., __comp=0x400edc <wordncompare(unsigned int, unsigned int)>) at /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:4822 #6 0x00000000004012d2 in main (argc=1, args=0x7fffffffe0b8) at text_gen2.cpp:70 I have similar code in another program, but in that program I am using a vector instead of vector. For the life of me I can't figure out what I'm doing wrong. Thanks!

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jquery radio button when checked need an alert

- by TIT

Hello In my application i need a radio group, in which whenever a button is checked, an alert occur so that i can post its value to ajax post in jquery. Can you help me please how i can do it in jquery?

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c++ stl priority queue insert bad_alloc exception

- by bsg

Hi, I am working on a query processor that reads in long lists of document id's from memory and looks for matching id's. When it finds one, it creates a DOC struct containing the docid (an int) and the document's rank (a double) and pushes it on to a priority queue. My problem is that when the word(s) searched for has a long list, when I try to push the DOC on to the queue, I get the following exception: Unhandled exception at 0x7c812afb in QueryProcessor.exe: Microsoft C++ exception: std::bad_alloc at memory location 0x0012ee88.. When the word has a short list, it works fine. I tried pushing DOC's onto the queue in several places in my code, and they all work until a certain line; after that, I get the above error. I am completely at a loss as to what is wrong because the longest list read in is less than 1 MB and I free all memory that I allocate. Why should there suddenly be a bad_alloc exception when I try to push a DOC onto a queue that has a capacity to hold it (I used a vector with enough space reserved as the underlying data structure for the priority queue)? I know that questions like this are almost impossible to answer without seeing all the code, but it's too long to post here. I'm putting as much as I can and am anxiously hoping that someone can give me an answer, because I am at my wits' end. The NextGEQ function is too long to put here, but it reads a list of compressed blocks of docids block by block. That is, if it sees that the lastdocid in the block (in a separate list) is larger than the docid passed in, it decompresses the block and searches until it finds the right one. If it sees that it was already decompressed, it just searches. Below, when I call the function the first time, it decompresses a block and finds the docid; the push onto the queue after that works. The second time, it doesn't even need to decompress; that is, no new memory is allocated, but after that time, pushing on to the queue gives a bad_alloc error. struct DOC{ long int docid; long double rank; public: DOC() { docid = 0; rank = 0.0; } DOC(int num, double ranking) { docid = num; rank = ranking; } bool operator>( const DOC & d ) const { return rank > d.rank; } bool operator<( const DOC & d ) const { return rank < d.rank; } }; struct listnode{ int* metapointer; int* blockpointer; int docposition; int frequency; int numberdocs; int* iquery; listnode* nextnode; }; void QUERYMANAGER::SubmitQuery(char *query){ vector<DOC> docvec; docvec.reserve(20); DOC doct; //create a priority queue to use as a min-heap to store the documents and rankings; //although the priority queue uses the heap as its underlying data structure, //I found it easier to use the STL priority queue implementation priority_queue<DOC, vector<DOC>,std::greater<DOC>> q(docvec.begin(), docvec.end()); q.push(doct); //do some processing here; startlist is a pointer to a listnode struct that starts the //linked list cout << "Opening lists:" << endl; //point the linked list start pointer to the node returned by the OpenList method startlist = &OpenList(value); listnode* minpointer; q.push(doct); //more processing here; else{ //start by finding the first docid in the shortest list int i = 0; q.push(doct); num = NextGEQ(0, *startlist); q.push(doct); while(num != -1) cout << "finding nextGEQ from shortest list" << endl; q.push(doct); //the is where the problem starts - every previous q.push(doct) works; the one after //NextGEQ(num +1, *startlist) gives the bad_alloc error num = NextGEQ(num + 1, *startlist); q.push(doct); //if you didn't break out of the loop; i.e., all lists contain a matching docid, //calculate the document's rank; if it's one of the top 20, create a struct //containing the docid and the rank and add it to the priority queue if(!loop) { cout << "found match" << endl; if(num < 0) { cout << "reached end of list" << endl; //reached the end of the shortest list; close the list CloseList(startlist); break; } rank = calculateRanking(table, num); try{ //if the heap is not full, create a DOC struct with the docid and //rank and add it to the heap if(q.size() < 20) { doc.docid = num; doc.rank = rank; q.push(doct); q.push(doc); } } catch (exception& e) { cout << e.what() << endl; } } } Thank you very much, bsg.

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double checked locking - objective c

- by bandejapaisa

I realised double checked locking is flawed in java due to the memory model, but that is usually associated with the singleton pattern and optimizing the creation of the singleton. What about under this case in objective-c: I have a boolean flag to determine if my application is streaming data or not. I have 3 methods, startStreaming, stopStreaming, streamingDataReceived and i protect them from multiple threads using: - (void) streamingDataReceived:(StreamingData *)streamingData { if (self.isStreaming) { @synchronized(self) { if (self.isStreaming) { - (void) stopStreaming { if (self.isStreaming) { @synchronized(self) { if (self.isStreaming) { - (void) startStreaming:(NSArray *)watchlistInstrumentData { if (!self.isStreaming) { @synchronized(self) { if (!self.isStreaming) { Is this double check uneccessary? Does the double check have similar problems in objective-c as in java? What are the alternatives to this pattern (anti-pattern). Thanks

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How to show that the double-checked-lock pattern with Dictionary's TryGetValue is not threadsafe in

- by Amir

Recently I've seen some C# projects that use a double-checked-lock pattern on a Dictionary. Something like this: private static readonly object _lock = new object(); private static volatile IDictionary<string, object> _cache = new Dictionary<string, object>(); public static object Create(string key) { object val; if (!_cache.TryGetValue(key, out val)) { lock (_lock) { if (!_cache.TryGetValue(key, out val)) { val = new object(); // factory construction based on key here. _cache.Add(key, val); } } } return val; } This code is incorrect, since the Dictionary can be "growing" the collection in _cache.Add() while _cache.TryGetValue (outside the lock) is iterating over the collection. It might be extremely unlikely in many situations, but is still wrong. Is there a simple program to demonstrate that this code fails? Does it make sense to incorporate this into a unit test? And if so, how?

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Change class of parent div if radio input checked

- by xxstevenxo

I've been searching and searching google for answers to my question but have been unsuccessful so far. I'm hoping one of you guys could give me some assistance. I have 10 divs with the class name "dividend" holding a table with the classname/id of "container" then two smaller tables inside that. Within the container table at the bottom is a hidden radio button with the name "page1". I wrote an onClcick for the container table so the user can select the whole table instead of the radio button, but not I'm trying to change the style of the selected container so the users know they have selected it. I have tried a few different methods and I'm able to change the style to the new class by just writing document.getElementById('container').className = 'selected'; But because all 10 divs share the same name it will only change the style of the first element it finds. So I tried writing this loop to check if there are any selected radios in the document then to change the else name the style as the default. I'm sure its something stupid but I'm pretty stumped atm.. Any help would be appreciated. Thanks. selected = function () { var divs = document.getElementByTagName('DIV'), div, tbl, rad, stat, i; for (i = 0; i < divs.length; i++) { div = divs.id; if (div == 'dividend') { tbl = div.getElementById('container'); rad = tbl.getElementByTagName('INPUT'); if (rad.checked = true) { tbl.className = 'selected'; } } } };

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Design approach, string table data, variables, stl memory usage

- by howieh

I have an old structure class like this: typedef vector<vector<string>> VARTYPE_T; which works as a single variable. This variable can hold from one value over a list to data like a table. Most values are long,double, string or double [3] for coordinates (x,y,z). I just convert them as needed. The variables are managed in a map like this : map<string,VARTYPE_T *> where the string holds the variable name. Sure, they are wrapped in classes. Also i have a tree of nodes, where each node can hold one of these variablemaps. Using VS 2008 SP1 for this, i detect a lot of memory fragmentation. Checking against the stlport, stlport seemed to be faster (20% ) and uses lesser memory (30%, for my test cases). So the question is: What is the best implementation to solve this requirement with fast an properly used memory ? Should i write an own allocator like a pool allocator. How would you do this ? Thanks in advance, Howie

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Sort list using stl sort function

- by Vlad

I'm trying to sort a list (part of a class) in descending containg items of a struct but it doesn't compile(error: no match for 'operator-' in '__last - __first'): sort(Result.poly.begin(), Result.poly.end(), SortDescending()); And here's SortDescending: struct SortDescending { bool operator()(const term& t1, const term& t2) { return t2.pow < t1.pow; } }; Can anyone tell me what's wrong? Thanks!

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How to avoid reallocation using the STL (C++)

- by Tue Christensen

This question is derived of the topic: http://stackoverflow.com/questions/2280655/vector-reserve-c I am using a datastructur of the type vector<vector<vector<double> > >. It is not possible to know the size of each of these vector (except the outer one) before items (doubles) are added. I can get an approximate size (upper bound) on the number of items in each "dimension". A solution with the shared pointers might be the way to go, but I would like to try a solution where the vector<vector<vector<double> > > simply has .reserve()'ed enough space (or in some other way has allocated enough memory). Will A.reserve(500) (assumming 500 is the size or, alternatively an upper bound on the size) be enough to hold "2D" vectors of large size, say [1000][10000]? The reason for my question is mainly because I cannot see any way of reasonably estimating the size of the interior of A at the time of .reserve(500). An example of my question: vector A; A.reserve(500+1); vector temp2; vector temp1 (666,666); for(int i=0;i<500;i++) { A.push_back(temp2); for(int j=0; j< 10000;j++) { A.back().push_back(temp1); } } Will this ensure that no reallocation is done for A? If temp2.reserve(100000) and temp1.reserve(1000) where added at creation will this ensure no reallocation at all will occur at all? In the above please disregard the fact that memory could be wasted due to conservative .reserve() calls. Thank you all in advance!

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C++/STL: std::transform with given stride?

- by Arman

Hello, I have a 1d array containing Nd data, I would like to effectively traverse on it with std::transform or std::for_each. unigned int nelems; unsigned int stride=3;// we are going to have 3D points float *pP;// this will keep xyzxyzxyz... Load(pP); std::transform(pP, pP+nelems, strMover<float>(pP, stride));//How to define the strMover?? Kind Regards, Arman.

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STL: writing "where" operator for a vector.

- by Arman

Hello, I need to find the indexes in the vector based on several boolean predicates. ex: vector<float> v; vector<int> idx; idx=where( bool_func1(v), bool_func2(v), ... ); What is the way to declare **where** function, in order to use the several user defined boolean functions over the vector? thanks Arman.

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Displaying map stl

- by BSchlinker

Declared a map early on: map<char*,char*> rtable; // used to store routing information Now I'm attempting to display the contents of the map: void Routes::viewroutes(){ typedef map<char*, char*>::const_iterator iter; for (iter=rtable.begin(); iter != rtable.end(); ++iter) { cout << iter->second << " " << iter->first << endl; } } Receiving the error "expected primary-expression before '!=' token and for '-' token. Can't seem to understand the error I'm making here. Any ideas?

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Using memcpy in the STL

- by wowus

Why does C++'s vector class call copy constructors? Why doesn't it just memcpy the underlying data? Wouldn't that be a lot faster, and remove half of the need for move semantics? I can't imagine a use case where this would be worse, but then again, maybe it's just because I'm being quite unimaginative.

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