Hi, I'm trying to code opposite action to this: std::ostream outs; // properly initialized of course std::set<int> my_set; // ditto outs << my_set.size(); std::copy( my_set.begin(), my_set.end(), std::ostream_iterator<int>( outs ) ); it should be something like this: std::istream ins; std::set<int>::size_type size; ins >> size; s...
I am using a set because, i want to use the quick look up property of a sorted container such as a set. I am wondering if I have to use the find member method to get the benefit of a sorted container, or can I also use the static find method in the STL algorithms? My hunch is that using the static version will use a linear search inste...
I have always wondered why you cannot use locally defined classes as predicates to STL algorithms. In the question: Approaching STL algorithms, lambda, local classes and other approaches, BubbaT mentions says that 'Since the C++ standard forbids local types to be used as arguments' Example code: int main() { int array[] = { 1, 2, ...
I've read that all stl containers provide a specialisation of the swap algorithm so as to avoid calling the copy constructor and two assignment operations that the default method uses. However, when I thought it would be nice to use a queue in some code I was working on I noticed that (unlike vector and deque) queue doesn't provide this ...
Greetings, I am trying to perform a copy from one vector (vec1) to another vector (vec2) using the following 2 abbreviated lines of code (full test app follows): vec2.reserve( vec1.size() ); copy(vec1.begin(), vec1.end(), vec2.begin()); While the call to vec2 sets the capacity of vector vec2, the copying of data to vec2 seems to not ...
Hi, As the function accepted by for_each take only one parameter (the element of the vector), I have to define a static int sum = 0 somewhere so that It can be accessed after calling the for_each . I think this is awkward. Any better way to do this (still use for_each) ? #include <algorithm> #include <vector> #include <iostream> us...
Hi! I was wandering how it's possible to reverese strings that are contained in a vector using a single for_each command just in one "simple" line. Yea, I know it is easy with a custom functor, but I can't accept, that it can't be done using bind (at least I couldn't do it). #include <vector> #include <string> #include <algorithm> std...
I am struggling to find out why I can't get transform to work with a template class. Here's a simplified version of the template class : template<typename T> class base { public : base() : all_() {} ~base() {} public: bool add(T t) { typename vector<T>::iterator itr = lower_bound(all_.begin(), all_.end(), t); i...
After learning good amount of c++, i'm now into STL containers and algorithms template library, my major concerns are, 1) Is this library same across different platforms like MS, linux n other os? 2) will quality or efficiency of program c++ module decrease with more use of STL containers and algorithms, i think i can't customize it to...
I've written a method that I'd like to declare as const, but the compiler complains. I traced through and found that this part of the method was causing the difficulty: bool ClassA::MethodA(int x) { bool y = false; if(find(myList.begin(), myList.end(), x) != myList.end()) { y = true; } return y; } There is ...
What's the return of the algorithm std:set_union when one or both input containers are multisets with duplicated objects? Do dups get lost? Let's suppose for example: multiset<int> ms1; ms1.insert(1); ms1.insert(1); ms1.insert(1); ms1.insert(2); ms1.insert(3); multiset<int> ms2; ms2.insert(1); ms2.insert(1); ms2.insert(2); ms2.insert(...
My goal here is to find all possible combinations that sums to a given total. For example, if the array is 2 59 3 43 5 9 8 62 10 4 and if the total is 12, then possible combinations are 2 10 3 9 8 4 5 3 4 Here is the first set of code, that I've written. Wondering the best improvements that can be done on this. int find_numbers...
Hello to everyone, I wonder if and how it is possible to define a function object inside a classes member function to use it directly with, for example, the std::transform function. I know the example is a bit stupid, it's just to show the problem I'm confronted with. File "example.h" class Example { public: //.. constructor and...
Why does this code result in a run-time error "vector iterator not incrementable"? vector<string> s1, s2; s1.push_back("joe"); s1.push_back("steve"); s1.push_back("jill"); s1.push_back("svetlana"); s2.push_back("bob"); s2.push_back("james"); s2.push_back("jill"); s2.push_back("barbara"); s2.push_back("steve"); sort(s1.begin...
#include <iostream> #include <set> #include <algorithm> #include <boost/lambda/lambda.hpp> #include <boost/bind.hpp> using namespace std; using namespace boost::lambda; class Foo { public: Foo(int i, const string &s) : m_i(i) , m_s(s) {} int get_i() const { return m_i; } const string &get_s() const { return m_s; } fri...