search
Homephp教程PHP开发Use of Iterator in c++ STL standard container

Most standard containers of C++ STL provide Iterator. Some containers, such as priority_queue, do not have Iterator because semantically they should not allow arbitrary traversal of elements in the container.

There is the iterator pattern among the 23 classic design patterns, and the java collection framework also implements this pattern:

Java code

package java.util;  
  
  
public interface Iterator<E> {  
  
    boolean hasNext();  
  
    E next();  
  
  
    void remove();  
}

C++’s iterator is more flexible than java, mainly reflected in:

1.java only A front-to-back iterator. In addition to front-to-back iterators, c++ also provides back-to-back iterators, such as:

Cpp code

map<int,int> amap;  
amap.insert(pair<int,int>(1,1));  
amap.insert(pair<int.int>(2,2));  
map<int,int>::iterator it;  
for(it = amap.begin();it != ampa.end();it++)//从前向后  
{  
    cout<<"key:"<<it->first<<" value:"<<it->second<<endl;

Cpp code

}

Cpp code

map<int,int>::reverse_iterator rit;  
for(rit = amap.rbegin();rit != amap.rend();rit++)//从后向前  
{  
     cout<<"key:"<<rit->first<<" value:"<<rit->second<<endl;  
}

2. In addition to iterator, c++ also provides const_iterator, which can only read the data in the collection, but cannot change its value.

3. Java’s iterator seems to only be able to increment in a single step, while c++’s iterator In addition, the iterator can also implement arithmetic operations, such as +n, -n, which is very useful for scenarios where a certain element needs to be read randomly. However, it seems that only the iterator of vector supports arithmetic operations. In other words, the iterator it in the previous example cannot perform operations such as it = it+n. This is important to remember.


Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Java Iterator 与 Iterable:揭秘迭代器与可迭代对象的世界Java Iterator 与 Iterable:揭秘迭代器与可迭代对象的世界Feb 19, 2024 pm 02:15 PM

在Java编程中,Iterator和Iterable接口是用于处理集合中元素的重要工具。Iterator接口提供了对集合元素进行迭代访问的方法,而Iterable接口则定义了集合的可迭代性,使集合中的元素可以通过Iterator访问。这两者的紧密配合,为我们提供了遍历集合元素的通用方法。Iterator接口Iterator接口定义了以下方法:booleanhasNext():检查集合中是否还有元素。Enext():返回集合中的下一个元素。voidremove():移除当前元素。Iterable接

Java Iterator 和 Iterable 的深入比较:优缺点分析Java Iterator 和 Iterable 的深入比较:优缺点分析Feb 19, 2024 pm 04:20 PM

概念差异:Iterator:Iterator是一个接口,代表一个从集合中获取值的迭代器。它提供了MoveNext()、Current()和Reset()等方法,允许你遍历集合中的元素,并对当前元素进行操作。Iterable:Iterable也是一个接口,代表一个可迭代的对象。它提供了Iterator()方法,用于返回一个Iterator对象,以便于遍历集合中的元素。使用方式:Iterator:要使用Iterator,需要先获得一个Iterator对象,然后调用MoveNext()方法来移动到下一

Java Iterator 与 Iterable:迈入编写优雅代码的行列Java Iterator 与 Iterable:迈入编写优雅代码的行列Feb 19, 2024 pm 02:54 PM

Iterator接口Iterator接口是一个用于遍历集合的接口。它提供了几个方法,包括hasNext()、next()和remove()。hasNext()方法返回一个布尔值,指示集合中是否还有下一个元素。next()方法返回集合中的下一个元素,并将其从集合中删除。remove()方法从集合中删除当前元素。以下代码示例演示了如何使用Iterator接口来遍历集合:Listnames=Arrays.asList("John","Mary","Bob");Iterator

Java Iterator和Iterable:集合遍历的密钥,揭开其神秘面纱Java Iterator和Iterable:集合遍历的密钥,揭开其神秘面纱Feb 20, 2024 am 10:27 AM

Iterator简介Iterator是Java中用于遍历集合的接口。它提供了一组方法,允许您以一种顺序的方式访问集合中的元素。您可以使用Iterator来遍历List、Set和Map等集合类型。演示代码:Listlist=newArrayList();list.add("one");list.add("two");list.add("three");Iteratoriterator=list.iterator();while(iter

Java Iterator和Iterable:揭露集合遍历的幕后故事Java Iterator和Iterable:揭露集合遍历的幕后故事Feb 19, 2024 pm 04:15 PM

迭代器(Iterator)和可迭代对象(Iterable)是Java集合框架中两个非常重要的接口。它们使您能够遍历集合中的元素,而无需了解集合的具体实现。Iterator接口定义了用于遍历集合的方法,包括hasNext()和next()。hasNext()方法检查集合中是否还有更多元素,而next()方法返回集合中的下一个元素。Iterable接口定义了一个用于创建Iterator的方法,即iterator()方法。该方法返回一个Iterator对象,该对象可以用于遍历集合。以下是使用Itera

如何使用Java中的Iterator函数进行集合遍历如何使用Java中的Iterator函数进行集合遍历Jun 26, 2023 pm 03:47 PM

在Java中,集合是一种常见的数据结构,它允许我们存储和处理大量数据。在许多情况下,我们需要对集合进行遍历,以便对其中的元素进行操作。为了实现这一目的,Java提供了Iterator函数,它可以让我们简便地遍历集合中的元素。在本文中,我们将介绍如何使用Java中的Iterator函数进行集合遍历。一、Iterator函数的定义在Java中,Iterator是

Java Iterator 与 Iterable:解锁 Java 集合的强大力量Java Iterator 与 Iterable:解锁 Java 集合的强大力量Feb 19, 2024 pm 07:00 PM

在Java中,集合(collection)是一组元素的集合,提供了统一的接口和方法来存储、检索和操作这些元素。Iterator和Iterable是两个重要的Java接口,它们提供了遍历集合元素的通用机制。Iterator接口定义了用于遍历集合的hasNext()和next()方法。hasNext()方法用于检查集合中是否还有未遍历的元素,next()方法用于返回当前元素并将其移至下一个元素。Iterable接口定义了iterator()方法,该方法返回一个Iterator对象,用于遍历集合中的元

Java Iterator 和 Iterable:深入剖析 Java 集合遍历机制Java Iterator 和 Iterable:深入剖析 Java 集合遍历机制Feb 19, 2024 pm 08:36 PM

Iterator接口Iterator接口是Java集合框架中用于遍历集合的低级接口。它定义了两个主要方法:hasNext():检查集合中是否还有更多元素。next():返回集合中的下一个元素。Iterator接口还定义了一些可选的方法,例如remove()方法,用于从集合中删除当前元素。使用Iterator接口可以使用以下步骤使用Iterator接口遍历集合:获取集合的Iterator对象。使用hasNext()方法检查集合中是否还有更多元素。如果还有更多元素,则使用next()方法获取下一个元

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

AI Hentai Generator

AI Hentai Generator

Generate AI Hentai for free.

Hot Article

R.E.P.O. Energy Crystals Explained and What They Do (Yellow Crystal)
2 weeks agoBy尊渡假赌尊渡假赌尊渡假赌
Repo: How To Revive Teammates
4 weeks agoBy尊渡假赌尊渡假赌尊渡假赌
Hello Kitty Island Adventure: How To Get Giant Seeds
4 weeks agoBy尊渡假赌尊渡假赌尊渡假赌

Hot Tools

Dreamweaver Mac version

Dreamweaver Mac version

Visual web development tools

Safe Exam Browser

Safe Exam Browser

Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

SAP NetWeaver Server Adapter for Eclipse

SAP NetWeaver Server Adapter for Eclipse

Integrate Eclipse with SAP NetWeaver application server.

SublimeText3 English version

SublimeText3 English version

Recommended: Win version, supports code prompts!