This container but not its members can be instantiated with an incomplete element type if the allocator satisfies the allocator completeness requirements.

Stack Overflow works best with JavaScript enabled. Asked 11 years, 4 months ago. From cppreference. Viewed 2. The elements are stored contiguously, which means that elements can be accessed not only through iterators, but also using offsets to regular pointers to elements. Getting the last element of a list Ask Question. Then you can be consistently doing everything the hard way in all of your projects. He provides a[-1] anyways too.

This is IMO the easiest way to get last element, because it does not require anything pythonic knowledge. These are valid use-cases, but not very common. The immediate answer to your question as to fetching access to the last element in a vector can be accomplished using the back member. How does the highlight. One certainty is that exceptions halt your app. In any event, exceptions are objects that halt your code. In such cases you can check your vector's empty-state prior to using back by using the empty member:. Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.

Hello highlight. Linked T must meet the requirements of CopyAssignable and CopyConstructible. Radek Anuszewski Radek Anuszewski 1, 5 5 gold badges 27 27 silver badges 53 53 bronze badges. Email Required, but never shown. Dashboard Logout. Taurus Olson Taurus Olson 2, 1 1 gold badge 23 23 silver badges 21 21 bronze badges. I shall update the answer in due course.

CygnusX1 CygnusX1 That is the only problem I have. MichaelWu There is no sense to do that. Email Required, but never shown. Note: If there is a possibility your vector is empty, such a call to back causes undefined behavior. Post as a guest Name. Nope; vec. And as I said, you may well be right that neither are warranted for participation in his final usage, but imho, both are warranted as a reminder to consider. Use back :. Viewed 78k times.

Goodbye, Prettify. The standard library provides a specialization of std::vector for the type bool , which may be optimized for space efficiency. Nope; vec. ChristianRau Now that I actually buy into. The immediate answer to your question as to fetching access to the last element in a vector can be accomplished using the back member. In such cases you can check your vector's empty-state prior to using back by using the empty member:. If the vector changed capacity, all of them. DevPlayer DevPlayer 4, 1 1 gold badge 19 19 silver badges 19 19 bronze badges.

Email Required, but never shown. A container is an object that holds data of the same type. The storage of the vector is handled automatically. The type of the elements. ChristianRau I have edited my answer, please take another look at it. Sanjay Pradeep Sanjay Pradeep 3 3 silver badges 6 6 bronze badges. Play the long game when learning to code. Featured on Meta. I have modified an example from the documentation to indicate which item in a sequence each index references, in this case, in the string "Python" , -1 references the last element, the character, 'n' :.

Note that getting a list item by index will raise an IndexError if the expected item doesn't exist. Attention reader! If the vector changed capacity, all of them. Erases all elements satisfying specific criteria function template [edit]. The element erased and end. The storage of the vector is handled automatically, being expanded and contracted as needed. A container is an object that holds data of the same type. You can also use the code below, if you do not want to get IndexError when the list is empty.

This method may unnecessarily materialize a second list for the purposes of just getting the last element, but for the sake of completeness and since it supports any iterable - not just lists :. It is good to teach such safety and cleannliness considerations to newbies, but likewise do you have to be especially careful to not indoctrinate them with dogmatic behaviour, but to think about the neccessity of such checks in each and every situation anew. I have a vector vec of structures. Generally, it is required that element type is a complete type and meets the requirements of Erasable , but many member functions impose stricter requirements. This means that a pointer to an element of a vector may be passed to any function that expects a pointer to an element of an array. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute. Valentin Podkamennyi Valentin Podkamennyi 6, 4 4 gold badges 21 21 silver badges 41 41 bronze badges. Chowlett Chowlett

Erased elements and all elements after them including end. Related LegacyRandomAccessIterator [edit]. In any event, exceptions are objects that halt your code. Load Comments. The elements are stored contiguously, which means that elements can be accessed not only through iterators, but also using offsets to regular pointers to elements. Alternatively, if, for some reason, you're looking for something less pythonic, you could use list[len list -1] , assuming the list is not empty. I wish Python had a function for first and last like Lisp does Getting a list when you want an element only postpones the inevitable "list index out of range" - and that's what should happen when attempting to get an element from an empty list. Jan 20 at

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below. Thats all, nothing beyond that. However I find there are two basic camps on what exception objects are intended for. Sign up or log in Sign up using Google. Stack Overflow works best with JavaScript enabled. Vectors are sequence containers whose size is changed dynamically. Language support library. Swapping out our Syntax Highlighter. It has a counterpart front as well. Wild Code Wild Code 50 9 9 bronze badges.

Goodbye, Prettify. Stack Overflow works best with JavaScript enabled. The Overflow Blog. I would like to assign to some int var the element c, from the last structure in a vector. If you change your algorithm in one place, it may have an unintended impact on another line of code. Such as:. T [edit]. You could just propose vec. Nope; vec. Responding to the Lavender Letter and commitments moving forward.

If you're new to programming, you should avoid this section, because it couples otherwise semantically different parts of algorithms together. Run this code. This is not semantically the last thing in the list. I have a vector vec of structures. Linked ChristianRau Now that I actually buy into. Load Comments. T [edit]. Hello highlight.

WhozCraig WhozCraig 57k 9 9 gold badges 66 66 silver badges bronze badges. You can also set list elements in this way. I don't know why you'd do it, but for completeness, since reversed returns an iterator which supports the iterator protocol you can pass its result to next :. Post as a guest Name. My preference is to use IF clauses to test for "null" objects instead of objects that halt my code that I preempt with a try clause. Sign up using Email and Password. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute. Responding to the Lavender Letter and commitments moving forward. ChristianRau Now that I actually buy into.

I don't know why you'd do it, but for completeness, since reversed returns an iterator which supports the iterator protocol you can pass its result to next :. I'm going circle in line like this:. Janusz Janusz k gold badges silver badges bronze badges. T must meet the requirements of CopyAssignable and CopyConstructible. In any event, exceptions are objects that halt your code. Namespaces Page Discussion. Erased elements and all elements after them including end. Sequence containers store elements strictly in a linear sequence.

Related The elements are stored contiguously, which means that elements can be accessed not only through iterators, but also using offsets to regular pointers to elements. This means that a pointer to an element of a vector may be passed to any function that expects a pointer to an element of an array. Create account Log in. Featured on Meta. And as such to me are less sequence object like then returned "null"-sequences which do not halt your code. Erases all elements satisfying specific criteria function template [edit]. Please use ide. You can also use the code below, if you do not want to get IndexError when the list is empty.

You could just propose vec. Vectors are sequence containers whose size is changed dynamically. Please can you provide me with this simple solution? Simon 8, 8 8 gold badges 41 41 silver badges 63 63 bronze badges. Yavuz Mester Yavuz Mester 3 3 silver badges 10 10 bronze badges. You can also set list elements in this way. Jan 20 at My preference is to use IF clauses to test for "null" objects instead of objects that halt my code that I preempt with a try clause. Post as a guest Name.

Linked Question feed. And as I said, you may well be right that neither are warranted for participation in his final usage, but imho, both are warranted as a reminder to consider. Cleb Namespaces Page Discussion. Here is the solution for your query. MichaelWu There is no sense to do that. Hello highlight. A slice of a list returns a new list - so we can slice from -1 to the end if we are going to want the element in a new list:. Contents 1 Template parameters 2 Specializations 3 Iterator invalidation 4 Member types 5 Member functions 5.

Linked Run this code. It depends on what you want to do with your list because the pop method will delete the last element. Downvoted because I feel the core of this answer is incorrect. Live Demo. Question feed. This is IMO the easiest way to get last element, because it does not require anything pythonic knowledge. DevPlayer DevPlayer 4, 1 1 gold badge 19 19 silver badges 19 19 bronze badges.

DevPlayer DevPlayer 4, 1 1 gold badge 19 19 silver badges 19 19 bronze badges. But Ok, it's your decision, granted. So the code isn't the problem, its the assumption its always the solution. Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below. Sasha Chedygov Sasha Chedygov k 25 25 gold badges 97 97 silver badges bronze badges. And as I said, you may well be right that neither are warranted for participation in his final usage, but imho, both are warranted as a reminder to consider. Responding to the Lavender Letter and commitments moving forward. This is not semantically the last thing in the list. Swapping out our Syntax Highlighter.

I don't know why you'd do it, but for completeness, since reversed returns an iterator which supports the iterator protocol you can pass its result to next :. Technical Specifications. Please comment if you think I'm leaving a caveat out. ChristianRau I have edited my answer, please take another look at it. In such cases you can check your vector's empty-state prior to using back by using the empty member: if! See your article appearing on the GeeksforGeeks main page and help other Geeks. I try to provide caveats and conditions as completely as I can, but I may have missed something. Next Page.

Getting a list when you want an element only postpones the inevitable "list index out of range" - and that's what should happen when attempting to get an element from an empty list. How does the highlight. One certainty is that exceptions halt your app. If not, only those at or after the insertion point including end. Email Required, but never shown. The elements are stored contiguously, which means that elements can be accessed not only through iterators, but also using offsets to regular pointers to elements. I would like to assign to some int var the element c, from the last structure in a vector. Generally, it is required that element type is a complete type and meets the requirements of Erasable , but many member functions impose stricter requirements.

No, dereferencing the end iterator is undefined behavior and not equivalent to back. Sasha Chedygov Sasha Chedygov k 25 25 gold badges 97 97 silver badges bronze badges. You could just propose vec. The elements are stored contiguously, which means that elements can be accessed not only through iterators, but also using offsets to regular pointers to elements. T must meet the requirements of CopyAssignable and CopyConstructible. He provides a[-1] anyways too. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. If the vector changed capacity, all of them. Dashboard Logout. One certainty is that exceptions halt your app.

To just get the last element, without modifying the list, and assuming you know the list has a last element i. T [edit]. Run this code. The type of the elements. He'll just take that for granted and start to spam std::vector::empty s all over the place. The immediate answer to your question as to fetching access to the last element in a vector can be accomplished using the back member. DevPlayer DevPlayer 4, 1 1 gold badge 19 19 silver badges 19 19 bronze badges. Stack Overflow works best with JavaScript enabled. I'm going circle in line like this:.

Then you can be consistently doing everything the hard way in all of your projects. Load Comments. It is good to teach such safety and cleannliness considerations to newbies, but likewise do you have to be especially careful to not indoctrinate them with dogmatic behaviour, but to think about the neccessity of such checks in each and every situation anew. I shall update the answer in due course. Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below. Thats all, nothing beyond that. Next Page. The element erased and end.

This means that a pointer to an element of a vector may be passed to any function that expects a pointer to an element of an array. Downvoted because I feel the core of this answer is incorrect. Swapping out our Syntax Highlighter. The total amount of allocated memory can be queried using capacity function. The requirements that are imposed on the elements depend on the actual operations performed on the container. Pneumokok You make point, but I would argue that list indexing is a very basic Python technique compared to say generators. To just get the last element, without modifying the list, and assuming you know the list has a last element i. Such as:.

You can also do: alist. Note: If there is a possibility your vector is empty, such a call to back causes undefined behavior. Question feed. He'll just take that for granted and start to spam std::vector::empty s all over the place. Duplicate of stackoverflow. My preference is to use IF clauses to test for "null" objects instead of objects that halt my code that I preempt with a try clause. Constant LegacyRandomAccessIterator [edit]. The requirements that are imposed on the elements depend on the actual operations performed on the container. This is IMO the easiest way to get last element, because it does not require anything pythonic knowledge. These are valid use-cases, but not very common.

Sequence containers store elements strictly in a linear sequence. Create account Log in. The type of the elements. Thats all, nothing beyond that. Load Comments. In such cases you can check your vector's empty-state prior to using back by using the empty member: if! Explanation please? If you change your algorithm in one place, it may have an unintended impact on another line of code. Viewed 78k times. Linked

If you're performing a complete iteration over the list already, the last element will still be referenced by the variable name assigned in the loop:. Duplicate of stackoverflow. How does the highlight. You can also do: alist. The reserve function can be used to eliminate reallocations if the number of elements is known beforehand. See your article appearing on the GeeksforGeeks main page and help other Geeks. Play the long game when learning to code. Valentin Podkamennyi Valentin Podkamennyi 6, 4 4 gold badges 21 21 silver badges 41 41 bronze badges.

Featured on Meta. Erases all elements satisfying specific criteria function template [edit]. Jan 20 at You could just propose vec. The type of the elements. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. This is semantically the last thing that the name, item , was bound to. Alternatively, if, for some reason, you're looking for something less pythonic, you could use list[len list -1] , assuming the list is not empty. I would like to assign to some int var the element c, from the last structure in a vector. How does the highlight.

Whereas attempting to access by index raises an IndexError which would need to be handled:. Explanation please? Erased elements and all elements after them including end. You can also do: alist. Sunidhi Bansal. I wish Python had a function for first and last like Lisp does Yavuz Mester Yavuz Mester 3 3 silver badges 10 10 bronze badges. Namespaces Page Discussion. This is not semantically the last thing in the list.

However I find there are two basic camps on what exception objects are intended for. Lars Lars 1, 10 10 silver badges 25 25 bronze badges. The requirements that are imposed on the elements depend on the actual operations performed on the container. So the code isn't the problem, its the assumption its always the solution. Language support library. Live Demo. Ivaylo Strandjev Ivaylo Strandjev Hello highlight. How does the highlight.

Namespaces Page Discussion. Viewed 2. Writing code in comment? Cleb Use back :. I have a vector vec of structures. T must meet the requirements of CopyAssignable and CopyConstructible. Active 3 months ago. Freestanding and hosted implementations.

Asked 11 years, 4 months ago. WhozCraig WhozCraig 57k 9 9 gold badges 66 66 silver badges bronze badges. The type must meet the requirements of Allocator. We use cookies to ensure you have the best browsing experience on our website. Allocator [edit]. From cppreference. For Strings astr[] could be a valid approach since it returns the same type as astr[-1], but I don't think the ':' helps to deal with empty lists and the question is about lists. He provides a[-1] anyways too.

No, dereferencing the end iterator is undefined behavior and not equivalent to back. A slice of a list returns a new list - so we can slice from -1 to the end if we are going to want the element in a new list:. He'll just take that for granted and start to spam std::vector::empty s all over the place. That is the only problem I have. Sondering Narcissist Sondering Narcissist 3 3 silver badges 8 8 bronze badges. Email Required, but never shown. These are valid use-cases, but not very common. I'm going circle in line like this:. From cppreference. Please use ide.

The requirements that are imposed on the elements depend on the actual operations performed on the container. It depends on what you want to do with your list because the pop method will delete the last element. The total amount of allocated memory can be queried using capacity function. Jan 20 at WhozCraig WhozCraig 57k 9 9 gold badges 66 66 silver badges bronze badges. Please use ide. Please comment if you think I'm leaving a caveat out. Why would you "avoid" an IndexError? Improved By : 19bcs