


C 17 Template Deduction Guides: A Simple Explanation
What are Template Deduction Guides?
Template deduction guides are a feature introduced in C 17 that assist the compiler in inferring template arguments for constructors. They provide a way to specify how constructor arguments and their types map to template parameters.
Why (and When) Do We Need Them?
Template deduction guides are necessary when the deduction of template arguments from constructor arguments cannot be done directly from the argument types. For example, initializing a vector from an iterator pair requires knowledge of the underlying value type of the iterator.
How to Declare Them?
Template deduction guides are declared using the following syntax:
template <template-argument-list> class-template id (function-parameter-list) -> deduced-type;</template-argument-list>
Here, template-argument-list indicates the template arguments that are being deduced, function-parameter-list represents the constructor arguments, and deduced-type is the resulting deduced template type.
Example:
Consider the std::vector constructor that takes an iterator pair:
template <typename iterator> void func(Iterator first, Iterator last) { vector v(first, last); }</typename>
To deduce the type T of the vector, we need to use a template deduction guide:
template <typename iterator> vector(Iterator b, Iterator e) -> vector<typename std::iterator_traits>::value_type>;</typename></typename>
This guide instructs the compiler to deduce T as the value_type of the std::iterator_traits for the given iterator type.
Aggregate Initialization with Deduction Guides:
Template deduction guides can also be used with aggregate initialization:
template <typename t> struct Thingy { T t; }; Thingy(const char *) -> Thingy<:string>; Thingy thing{"A String"}; //thing.t is a `std::string`.</:string></typename>
In this example, the deduction guide enables the initialization of Thingy with a const char* while deducing T as std::string.
Note: Deduction guides are only used to infer template arguments. The actual initialization process follows the same rules as before, regardless of the chosen deduction guide.
The above is the detailed content of How Do C 17 Template Deduction Guides Simplify Template Argument Inference?. For more information, please follow other related articles on the PHP Chinese website!

C Learners and developers can get resources and support from StackOverflow, Reddit's r/cpp community, Coursera and edX courses, open source projects on GitHub, professional consulting services, and CppCon. 1. StackOverflow provides answers to technical questions; 2. Reddit's r/cpp community shares the latest news; 3. Coursera and edX provide formal C courses; 4. Open source projects on GitHub such as LLVM and Boost improve skills; 5. Professional consulting services such as JetBrains and Perforce provide technical support; 6. CppCon and other conferences help careers

C# is suitable for projects that require high development efficiency and cross-platform support, while C is suitable for applications that require high performance and underlying control. 1) C# simplifies development, provides garbage collection and rich class libraries, suitable for enterprise-level applications. 2)C allows direct memory operation, suitable for game development and high-performance computing.

C Reasons for continuous use include its high performance, wide application and evolving characteristics. 1) High-efficiency performance: C performs excellently in system programming and high-performance computing by directly manipulating memory and hardware. 2) Widely used: shine in the fields of game development, embedded systems, etc. 3) Continuous evolution: Since its release in 1983, C has continued to add new features to maintain its competitiveness.

The future development trends of C and XML are: 1) C will introduce new features such as modules, concepts and coroutines through the C 20 and C 23 standards to improve programming efficiency and security; 2) XML will continue to occupy an important position in data exchange and configuration files, but will face the challenges of JSON and YAML, and will develop in a more concise and easy-to-parse direction, such as the improvements of XMLSchema1.1 and XPath3.1.

The modern C design model uses new features of C 11 and beyond to help build more flexible and efficient software. 1) Use lambda expressions and std::function to simplify observer pattern. 2) Optimize performance through mobile semantics and perfect forwarding. 3) Intelligent pointers ensure type safety and resource management.

C The core concepts of multithreading and concurrent programming include thread creation and management, synchronization and mutual exclusion, conditional variables, thread pooling, asynchronous programming, common errors and debugging techniques, and performance optimization and best practices. 1) Create threads using the std::thread class. The example shows how to create and wait for the thread to complete. 2) Synchronize and mutual exclusion to use std::mutex and std::lock_guard to protect shared resources and avoid data competition. 3) Condition variables realize communication and synchronization between threads through std::condition_variable. 4) The thread pool example shows how to use the ThreadPool class to process tasks in parallel to improve efficiency. 5) Asynchronous programming uses std::as

C's memory management, pointers and templates are core features. 1. Memory management manually allocates and releases memory through new and deletes, and pay attention to the difference between heap and stack. 2. Pointers allow direct operation of memory addresses, and use them with caution. Smart pointers can simplify management. 3. Template implements generic programming, improves code reusability and flexibility, and needs to understand type derivation and specialization.

C is suitable for system programming and hardware interaction because it provides control capabilities close to hardware and powerful features of object-oriented programming. 1)C Through low-level features such as pointer, memory management and bit operation, efficient system-level operation can be achieved. 2) Hardware interaction is implemented through device drivers, and C can write these drivers to handle communication with hardware devices.


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

Zend Studio 13.0.1
Powerful PHP integrated development environment

SublimeText3 Linux new version
SublimeText3 Linux latest version

DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software

Notepad++7.3.1
Easy-to-use and free code editor

MantisBT
Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.