This question already has answers here: How do I remove an item from a stl vector with a certain value? (11 answers) Closed 5 years ago. vector<int> myVector; and lets say the values in the vector are this (in this order): 5 9 2 8 0 7 If I wanted to erase the element that … Read more
This question already has answers here: How to find out if an item is present in a std::vector? (17 answers) Closed 2 years ago. Is there something in <algorithm> which allows you to check if a std:: container contains something? Or, a way to make one, for example: if(a.x == b.x && a.y == b.y) … Read more
I need to take a C++ vector with potentially a lot of elements, erase duplicates, and sort it. I currently have the below code, but it doesn’t work. vec.erase( std::unique(vec.begin(), vec.end()), vec.end()); std::sort(vec.begin(), vec.end()); How can I correctly do this? Additionally, is it faster to erase the duplicates first (similar to coded above) or perform … Read more
Suppose I have a vector that is nested in a dataframe one or two levels. Is there a quick and dirty way to access the last value, without using the length() function? Something ala PERL’s $# special var? So I would like something like: dat$vec1$vec2[$#] instead of dat$vec1$vec2[length(dat$vec1$vec2)] 11 Answers 11
What are the difference between a std::vector and an std::array in C++? When should one be preferred over another? What are the pros and cons of each? All my textbook does is list how they are the same. 6 Answers 6
Suppose I have a std::vector (let’s call it myVec) of size N. What’s the simplest way to construct a new vector consisting of a copy of elements X through Y, where 0 <= X <= Y <= N-1? For example, myVec [100000] through myVec [100999] in a vector of size 150000. If this cannot be … Read more
Should I use std::sort(numbers.begin(), numbers.end(), std::greater<int>()); or std::sort(numbers.rbegin(), numbers.rend()); // note: reverse iterators to sort a vector in descending order? Are there any benefits or drawbacks with one approach or the other? 11 Answers 11
How do I print out the contents of a std::vector to the screen? A solution that implements the following operator<< would be nice as well: template<container C, class T, String delim = “, “, String open = “[“, String close = “]”> std::ostream & operator<<(std::ostream & o, const C<T> & x) { // … What … Read more
How do I print out the contents of a std::vector to the screen? A solution that implements the following operator<< would be nice as well: template<container C, class T, String delim = “, “, String open = “[“, String close = “]”> std::ostream & operator<<(std::ostream & o, const C<T> & x) { // … What … Read more
What are the differences between the two data structures ArrayList and Vector, and where should you use each of them? 7 Answers 7
