iterator

Fastest Proxy Iteration in Python

由 孤者浪人 提交于 2021-02-17 06:10:14
问题 Let's say I have a list that contains 10,000+ proxies proxy_list = ['ip:port','ip:port',.....10,000+ items] How do I iterate it to get the proxies that works for my pc? Using the following code it is possible to find it , but takes 5*10,000 seconds to get completed. How would I iterate through the list faster? import requests result=[] for I in proxy_list: try: requests.get('http:\\www.httpbin.org\ip',proxies = {'https' : I, 'http' : I } ,timeout = 5) result.append(I) except: pass 回答1: You

using erase with remove_if

由 若如初见. 提交于 2021-02-17 04:53:09
问题 This thing drive me crazy, I couldn't understand it : // v contains : 101, 1, 2, 3, 4 , 5 v.erase(remove_if(v.begin(), v.end(), bind2nd(less<int>(), 3)), v.end()); // v contains now : 101, 3, 4, 5 Why there is v.end() as a second argument in erase ?? I read that remove_if returns an iterator to the element that follows the last element not removed, what does it mean.... v.erase(v.begin(), v.end()) should erase all the vector elements, but how in the example above it does not erase 3, 4 and 5

ConcurrentModificationException while using Iterator<Node> [duplicate]

由 ≡放荡痞女 提交于 2021-02-17 03:29:32
问题 This question already has answers here : Concurrent Modification Exception : adding to an ArrayList (10 answers) Closed 7 months ago . I was trying to delete a row of JavaFX GridPane with JavaFX Rectangles and I found no way to do so but copying the squares above to one row below . Here is my code to do that but it keeps throwing ConcurrentModificationAcception . static void copyAbove(int rowToBeDisappear, GridPane mainGrid) { for (int y = (rowToBeDisappear-1); 0 <= y ; y--) { for (int x = 0;

C2676: binary '<': 'const _Ty' does not define this operator or a conversion to a type acceptable to the predefined operator

由 佐手、 提交于 2021-02-17 03:00:51
问题 I keep getting this error for the code below. Upon reading this, I believed my error to be the it++ in my for loop, which I tried replacing with next(it, 1) but it didn't solve my problem. My question is, is the iterator the one giving me the issue here? #include <iostream> #include <vector> #include <stack> #include <set> using namespace std; struct Node { char vertex; set<char> adjacent; }; class Graph { public: Graph() {}; ~Graph() {}; void addEdge(char a, char b) { Node newV; set<char>

Enumerator.MoveNext() throws 'Collection was Modified' on first call

由 夙愿已清 提交于 2021-02-16 13:34:53
问题 Consider the following code: List<int> list = new List<int>(); IEnumerable<int> enumerable = list; IEnumerator<int> enumerator = enumerable.GetEnumerator(); list.Add(1); bool any = enumerator.MoveNext(); At runtime, the last line throws an: InvalidOperationException: Collection was modified; enumeration operation may not execute. I understand the need for IEnumerators to throw 'Collection was modified' exceptions when the IEnumerable changes, but I don't understand this: Why does the

Enumerator.MoveNext() throws 'Collection was Modified' on first call

由 坚强是说给别人听的谎言 提交于 2021-02-16 13:33:22
问题 Consider the following code: List<int> list = new List<int>(); IEnumerable<int> enumerable = list; IEnumerator<int> enumerator = enumerable.GetEnumerator(); list.Add(1); bool any = enumerator.MoveNext(); At runtime, the last line throws an: InvalidOperationException: Collection was modified; enumeration operation may not execute. I understand the need for IEnumerators to throw 'Collection was modified' exceptions when the IEnumerable changes, but I don't understand this: Why does the

How does subtracting X.begin() return the index of an iterator?

由 有些话、适合烂在心里 提交于 2021-02-13 17:27:49
问题 Having trouble understanding the below code: int data[5] = { 1, 5, 2, 4, 3 }; vector<int> X(data, data+5); int v1 = *max_element(X.begin(), X.end()); // Returns value of max element in vector int i1 = min_element(X.begin(), X.end()) – X.begin(); // Returns index of min element in vector Not really sure how subtracting the iterator returned by X.begin returns the index of the max/min element? 回答1: std::vector<T>::iterator satisfies the RandomAccessIterator concept, which means that it has an

How does subtracting X.begin() return the index of an iterator?

由 微笑、不失礼 提交于 2021-02-13 17:25:50
问题 Having trouble understanding the below code: int data[5] = { 1, 5, 2, 4, 3 }; vector<int> X(data, data+5); int v1 = *max_element(X.begin(), X.end()); // Returns value of max element in vector int i1 = min_element(X.begin(), X.end()) – X.begin(); // Returns index of min element in vector Not really sure how subtracting the iterator returned by X.begin returns the index of the max/min element? 回答1: std::vector<T>::iterator satisfies the RandomAccessIterator concept, which means that it has an

ConcurrentModificationException的原因以及解决措施

由 老子叫甜甜 提交于 2021-02-13 07:21:18
1. ConcurrentModificationException异常出现的原因 先看下面这段代码： package test; import java.util.ArrayList; import java.util.Iterator; public class test { public static void main(String[] args) { ArrayList<Integer> list = new ArrayList<Integer>(); list.add(2); Iterator<Integer> iterator = list.iterator(); while (iterator.hasNext()) { Integer integer = iterator.next(); if (integer == 2) list.remove(integer); } } } 运行结果： 从异常信息可以发现，异常出现在checkForComodification()方法中。 　　我们不忙看checkForComodification()方法的具体实现，我们先根据程序的代码一步一步看ArrayList源码的实现： 　　首先看ArrayList的iterator()方法的具体实现，查看源码发现在ArrayList的源码中并没有iterator()这个方法

How to implement erase on vector in c++

由 大憨熊 提交于 2021-02-11 18:15:59
问题 Learning from Accelerated C++: Practical Programming by Example , in chapter 11, there was an implementation (only with basic features) of vector container from STL. After that was an exercise for implementing erase function just as std::vector does. What I have tried: #include <memory> template<class T> class Vec{ private: T *data; T *avail; T *limit; std::allocator<T> alloc; ... public: explicit Vec(size_t n, const T &val = T()) { create(n, val); } T *const begin() { return data; } T *const
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