C++ Tutorial Index

C++ Tutorial C++ History C++ Installation C++ First Program C++ cin and cout C++ Data type C++ Variable C++ operator C++ Keywords

C++ Control Statements

C++ If C++ Nested if C++ If-else C++ If-else-if C++ Switch C++ Break C++ Continue C++ Goto C++ For loop C++ While loop C++ Do while loop

C++ Functions

C++ Call by Value C++ Call by Reference C++ Recursion Function C++ Inline function C++ Friend function

C++ Arrays

Single dimension array Two dimension array

C++ Strings

C++ Strings

C++ Inheritance

C++ Inheritance Single level Inheritance Multilevel Inheritance Multiple Inheritance Hierarchical Inheritance Hybrid Inheritance

C++ Polymorphism

C++ Polymorphism C++ Overloading C++ Overriding C++ Virtual Function

C++ Pointers

C++ Pointers C++ this pointer

C++ Exception Handling

C++ Exception Handling

C++ Constructors

C++ Constructors Default Constructor Parameterize Constructor Copy constructor Constructor Overloading Destructor

C++ File Handling

C++ File Handling C++ Writing to file C++ Reading file C++ Close file

Miscellaneous

C Vs C++ C++ Comments C++ Data Abstraction C++ Identifier C++ Memory Management C++ Storage Classes C++ Void Pointer C++ Array To Function C++ Expressions C++ Features C++ Interfaces C++ Encapsulation std::min in C++ External merge sort in C++ Remove duplicates from sorted array in C++ Precision of floating point numbers Using these functions floor(), ceil(), trunc(), round() and setprecision() in C++ C++ References C++ Friend Functions C++ Mutable keyword Unary Operators in C++ Initialize Array of objects with parameterized constructors in C++ Differences between #define & const in C/C++ C++ Program to Implement Shell Sort C++ Program to Implement Merge Sort Storage Classes in C Vector resize() in C++ Passing by Reference Vs. Passing by the pointer in C++ Free vs delete() in C++ goto statement in C and C++ C++ program to read string using cin.getline() C++ String Concatenation Heap Sort in C++ Swap numbers in C++ Input Iterators in C++ Fibonacci Series in C++ C ++ Program: Alphabet Triangle and Number Triangle C++ Program: Matrix Multiplication C++ Program to Print Fibonacci Triangle Stack in C++ Maps in C++ Queue in C++ C++ Bitset C++ Algorithms Priority Queue in C++ C++ Multimap C++ Deque Function Pointer in C++ Sizeof() Operators in C++ C++ array of Pointers free() Vs delete in C Timsort Implementation Using C++ CPP Templates C++ Aggregation C++ Enumeration C++ Math Functions C++ Object Class C++ Queue Initialize Vector in C++ Vector in C++ C++ STL Components Function overloading in C++ C++ Maximum Index Problem C++ find missing in the second array C++ Program to find the product array puzzle C++ Program To Find Largest Subarray With 0 Sum C++ Program To Move All Zeros To The End Of The Array C++ Program to find the element that occurs once C++ Program to find the largest number formed from an array Constructor Vs Destructor C++ Namespaces C++ OOPs Concept C++ Static C++ Structs C++ Try-Catch C++ User Defined Exceptions C++ Virtual Destructor C++ vs C# Malloc() and new in C++ Palindrome Number Program in C++ Snake Code in C++ Splitting a string in C++ Structure Vs Class in C++ Virtual Function Vs Pure Virtual Function C++ Bidirectional Iterators C++ Forward Iterators C++ Iterators C++ Output Iterators C++ Range-based For Loop Converting string into integer in C++ LCM Program in C++ Type conversion in C++ Add two numbers using the function in C++ Advantage and disadvantage friend function C++ Armstrong Number Program in C++ ATM machine program in C++ using functions Binary to Decimal in C++ Bit Manipulation in C++ C++ Constructor C++ Dijkstra Algorithm Using the Priority Queue C++ int into String C++ Signal Handling Decimal to Binary in C++ Decimal to Hexadecimal in C++ Decimal to Octal in C++ Factorial Program in C++ Function in C++ Hexadecimal to Decimal in C++ Octal to Decimal in C++ Reverse a Number in C++ Structure Vs Class in C++ C++ Forward Iterators C++ Output Iterators C++ Prime number program Char Array to String in C++ Constructor Overloading in C++ Default arguments in C++ Different Ways to Compare Strings in C++ Dynamic Binding in C++ Program to convert infix to postfix expression in C++ SET Data Structure in C++ Upcasting and Downcasting in C++ Reverse an Array in C++ Fast Input and Output in C++ Delete Operator in C++ Copy elision in C++ C++ Date and Time C++ Bitwise XOR Operator Array of sets in C++ Binary Operator Overloading in C++ Binary Search in C++ Implementing the sets without C++ STL containers Scope Resolution Operator in C++ Smart pointers in C++ Types of polymorphism in C++ Exception Handling in C++ vs Java Const Keyword in C++ Type Casting in C++ Static keyword in C++ vs Java Inheritance in C++ vs Java How to concatenate two strings in C++ Programs to Print Pyramid Patterns in C++ swap() function in C++ Structure of C++ Program Stringstream in C++ and its applications rand() and srand() in C / C++ C++ Ternary Operator C++ Scope of Variables While Loop Examples in C++ Star pattern in C++ using For Loops For Loop Examples in C++ Do-While Loop Examples in C++ Top 5 IDEs for C++ That You Should Try Once Assertions in C/C++ C++ Convert Int to String Continue in C++ While loop Diamond Pattern in C++ using For Loop How to Reverse a String in C++ using Do-While Loop How to Reverse a String in C++ using For Loop How to Reverse a String in C++ using While Loop Infinite loop in C++ Loops in C++ Returning Multiple Values from a Function using Tuple and Pair in C++ wcscpy(), wcslen(), wcscmp() Functions in C++ Auto keyword in C++ C++ 11 vs C++ 14 vs C++ 17 C++ STL (Standard Template Library) Differences Between C Structures and C++ Structures Divide by Zero Exception in C++ Dynamic Constructor in C++ Dynamic Memory Allocation in C++ Find the Size of Array in C/C++ without using sizeof() function Floating Point Operations and Associativity in C, C++ and Java Hello World Program in C++ How to create a table in C++ How to Setup Environment for C++ Programming on Mac Implementation of a Falling Matrix in C++ Message Passing in C++ Pointer to Object in C++ Templates in C++ vs Generics in Java Ways to Copy a Vector in C++ What does Buffer Flush mean in C++ sort() function in C++ Structure Sorting (By Multiple Rules) in C++ Similarities between C++ and Java std::distance in C++ Array program in C++ C++ Tricks for Competitive Programming Desired Capabilities in Selenium Web Driver in C++ Socket Programming in C++ Template Specialization in C++ Classes and Objects in C++ Convex hull Algorithm in C++ DES in C++ C++ vardiac() function Difference between Two Sets in C++ Difference between Exit and Return Structured Binding in C++ Differences between Local and Global Variable Bitwise Operator vs Logical Operator Difference between OOP and POP in C++ Fork in C++ Functors in C++ How to call a void function in C++ How to create a directory or folder in C/C++ How to create a library in C++ How to create a stack in C++ How to create the Processes with Fork in C++ How to Handle Divide by Zero Exception in C++ Lambda Expression in C++ Pattern programs in C++ Roadmap to C++ Programming Substring in C++ Virtual base class in C++ Bits stdc++.h in C++ Top 14 Best Free C++ IDE (Editor & Compiler) for Windows in 2022 Bitmasking in C++ Auto Keyword in C++ Features of OOPS in C++ Hospital Management Project in C++ How to Declare Unordered Sets in C++ How to Sort an Array in C++ Include Guards in C++ Iostream in C++ Method overriding in C++ How to run program in turbo c++ How to Use Getline in C++ Leap Year Program in C++ Naming Convention in C++ New Operator in C++ Nullptr in C++ Object Slicing in C++ Principles of Object-Oriented Programming in C++ Processing strings using std string stream in C++ Pure Virtual Function in C++ With Example Program Random Number Generator in C++ Singleton Design Pattern in C++ Size_t Data Type in C++ Skyline Problem in C++ System() function in C++ Web Development in C++ Data Hiding in C++ Difference between exit() and _Exit() in C++ Hashing in C++ Object in C++ Sum of all Elements between k1’th and k2’th Smallest Elements Virtual class in C++ Vector Size in C++ Top best IDEs for C/C++ Developers in 2022 Tensorflow in C++ Sliding Window Technique in C++ Reverse String Word-Wise in C++ Returning a Function Pointer from a Function in C/C++ RTTI in C++ Pthreads or POSIX Threads in C++ Reserved Keywords in C++ Passing a Vector to a function in C++ 10 Best C and C++ Books for Beginners & Advanced Programmers Add two numbers represented by two arrays in C++ Array of Object in C++ C++ Program For FCFS Containership in C++ Counting Frequencies of Array Elements in C++ Decltype type Specifier in C++ Dynamic _Cast in C++ Difference between int main() and int main(void) in C/C++ Depth First Search Program to Traverse a Graph in C++ Features and Use Of Pointers in C/C++ Fread Function in C++ Programming Fscanf Function in The C++ Functions in C++ With Types and Examples Gmtime Function in C/C++ How is Multiset Implemented in C++ How to Build a Program in C++ How to Declare a 2d Array Dynamically in C++ inheritance Program in C++ int Max and int Min in C/C++ is It Fine to Write Void Main Or Main in C/C++ How to create a button in C++ abs() function in C++ Compile Time Polymorphism in C++ Division in C++ Factorial of a Number in C++ using while Loop Multiset in C++ 4 Pillars of OOPs Approach in C++ Backtracking Time Complexity in C++ C++ Global Variable C++ Pipe Tutorial Observer Design Pattern in C++ Private Inheritance in C++ Pthread in C++ Parameters SDL library in C++ with Examples Pointers in C++ Abstract Factory Design Pattern in C++ Ascending order in C++ How the value is passed in C++ Call by Pointer in C++ Constexpr in C++ Deadlock in C++ Design Patterns in C++ Factory Method for Designing Pattern in C++ How to calculate size of string in C++ Name Mangling and extern in C++ Preventing Object Copy in C++ Program that produces different results in C and C++ Quick Sort in C++ Single Handling in C++ Type difference of Character literals in C VS C++ Use of Inheritance in C++ User-defined literals in C++ Vector methods in C++ Void * in C and C++ Zombie and Orphan Process in C++ Isprint() in C++ List and Vector in C++ List iterators in C++ Merging Two Vectors in C++ Sleep function in C++ Stoi function in C++ String erase() in C++ String Trim in C++ When should we write own Assignment operator in C++ C++ tcp client server example C++ tcp server example Early Binding and Late Binding in C++ Factory Design Pattern in C++ Fisher-Yates shuffle algorithm in C++ For Auto in C++ Group anagrams in C++ How to convert binary string to int in C++ How to convert string to float in C++ How to remove space from string in C++ How to use pair in C++ How to use the string find() in C++ Dynamic Casting in C++ 2D Vector Initialization in C++ C++ GUI Visual Studio C++ IPC C++ Macro Function Example C++ Permutation Overloading Stream Insertion in C++ Overloading array Index operator in C++ Operators that cannot be overloaded in C++ Operator overloading in C++ isprint() function in c++ Is_trivial function in C++ Is assignment operator Inherited in C++ div() function in C++ Default Assignment Operator and References in C++ Copy Constructor vs Assignment Operator in C++ Conversion Operator in C++ Array sum in C++ STL C++ Define Macro C++ Design C++ Factory Pattern TCP Client Server Example in C++ Convert String to Uppercase in C++ exit() and _Exit() in C and C++ Initializer list in C++ Iterator invalidation in C++ Lower bound in C++ Modulus of Two float numbers or double number Pass by value in C++ Set insert function in C++ Std partition_point in C++ Unary Operator Overloading in C++ Using Default Arguments with Virtual Functions Virtual Functions and Runtime Polymorphism What is endl in C++ What is Unary Operator Overloading in C++ Which operators cannot be overloaded in C++ C++ Program to Divide the String Into N equal Parts Gray Code to Binary Code in C++ How to get the value of pi in C++ Multimap value_comp() function in C++ Vector of Vectors in C++ Naïve Bayes Algorithm in C++ Minimum Cost Path Problem in C++ 10 C++ Programming Tricks You Should Know btowc() function in C++ forward_list::cend() in C++ Unordered_multimap max_load_factor() function in C++ Cpp_int in c++ Dynamic Objects in C++ FLOCK() FUNCTION IN C++ Generate Random Double Numbers in C++ How to Assign Infinity to a Number in C++ Jump statements in C++ Multipath inheritance in C++ Out of Range Exception in C++ Size of Class in C++ Size of string in C++ std::binary_negate in c++ Thread_local in C++ Tokenizing a String in C++ Ancestors of a Node in Binary Search Tree C++ program for Double to String Conversion C++ Program to Demonstrate Use of Formatting Flags on Float Output Clamp in C++ K-Dimensional Tree in C++ Mutable Lambda in C++ Power Set in C++ Program to Find Sum of Geometric Progression Std::Back_inserter in C++ Strpbrk() function in C++ Size of int in C++ TYPES OF MANIPULATORS IN C++ Double colon in C++ How to sort vector in C++ How to use Setprecision in C++ How to write a Vector in C++ Insertion in Splay Tree in C++ Merge Sort Algorithm in C++ Printing a Character using ASCII value in C++ Regex in C++ Size of Data Types in C++ Sqrtf() function in C++ Static Casting in C++ Using Range in Switch Case in C++ wcstoimax() and wcstoumax() function in C++ What is float in C++ What is the Diamond Problem in C++ Best way to learn C++ ios setstate() function in C++ Nested Namespace in C++ Single Inheritance in C++ std::fixed, std::scientific, std::hexfloat, std::defaultfloat in C++ StringStream in C++ for Decimal to Hexadecimal and back The OFFSETOF() macro in C++ Difference between std::next and std::advance in C++ Hiding of all overloaded methods with same name in base class in C++ C++ program to concatenate two strings using operator overloading Difference between array::fill() and array::swap() in C++ Difference between Friend Function and Virtual Function in C++ Semaphores in C++ Seekg in C++ UDP server- client implementattion in C++ What is long long in C++ CSV file management using C++ Toggle bits of a number except first and last bits in C++ Trailing Return Type C++ 11 Binary search implementation in C++ Different Versions of C++ What is Cascading in C++ Background Colour in C++ BOOL DATATYPE IN C++ BIT VECTORS IN C++ Literals in C++ Application of pointer in C++ Index with minimum sum of prefix and suffix sums in an array in C++ Maximum sum Bi-tonic sub-sequence in C++ std::optional in C++ C/C++ program for triangular matchstick number COUT COMMAND IN C++ LANGUAGE Adjacency matrix program in C++ language Difference between Null String and Empty String in C++ Character data type in c++ Constructors in Inheritance C++ Comma Operator Overloading in C++ Structure and Class in C++ Template Definition in C++ Tree Data Structure in C++ Typename in C++ C++ program to implement the bin packing algorithm How to merge multiple std::sets into a single std::set in C++? Stack Clear C++ C++ Friend Class Seekg in C++ Semaphores in C++ C++ Exceptions Difference Between C and C++ Double-linked list program in C++ Color Code in C++ CRC Program in C++ Anti-Clockwise spiral traversal of a binary tree in C++ Advantages of OOP in C++ Cryptarithmetic Puzzle in C++ Angular sweep algorithm in C++

Trailing Return Type C++ 11

An alternative method of indicating a function's return type in C++ is to use trailing return types, which place the function's return type after the parameter list rather than before the function name. The main objective of this C++11 feature was to improve code readability, particularly in situations involving complex return types.

Syntax:

It has the following syntax:

auto function_name(parameter_list) -> return_type {

// function body

}

Benefits:

There are several benefits of the trailing return type in C++. Some benefits of the trailing return type in C++ are as follows:

Improved Readability: Function declarations are frequently made easier to understand by trailing return types, especially when the functions have complex return types.

Flexibility in Type Deduction: They allow type deduction to rely on parameters, which is necessary for some template-based methods.

Decltype Integration: Trailing return types seamlessly integrate with decltype to determine types based on expressions inside the function.

// Traditional return type declaration:

std::vector<int>::iterator find_element(std::vector<int>& vec, int value) {

// ...

}

// Trailing return type declaration:

auto find_element(std::vector<int>& vec, int value) -> std::vector<int>::iterator {

// ...

}

When to Consider Trailing Return Types:

  • When the type of return is complex or long.
  • When composing template functions that rely on template arguments for their return types.
  • When the return type is automatically determined using decltype.
  • When aiming for a coding style that is consistent and puts readability first.

Syntax of Trailing Return Type

Here's the basic syntax for using trailing return types in C++ function declarations:

auto function_name(parameter_list) -> return_type {

// function body

}

Explanation:

  • auto Keyword: The return type will be specified later using the trailing return arrow (->), and this keyword serves as a placeholder for it.
  • function_name: It is the name of the function that you select.
  • parameter_list: It is the list, delimited by parenthesis, of the function's parameters.
  • return_type: The function's actual return type, trailing after the return arrow.

As an illustration:

Simple Function with a Basic Return Type:

auto add(int x, int y) -> int {

return x + y;

}

Function with a Nested Return Type:

auto find_max_element(std::vector<int>& vec) -> std::vector<int>::iterator {

return std::max_element(vec.begin(), vec.end());

}

Function Using decltype for Type Deduction:

template <typename T>

auto create_vector(size_t size) -> std::vector<T> {

return std::vector<T>(size);

}

Use Cases and Examples of Trailing Return Types

Trailing return types excel when it comes to complex type expressions, template metaprogramming, and scenarios where the return type is dependent on function arguments or template parameters. Here are some important situations in which they perform well:

  • Template Metaprogramming:

Simplifying Nested Type Dependencies:

#include <iostream>

#include <vector>

template <typename T>

auto get_iterator_type(T& container) -> typename T::iterator {

return container.begin();

}

int main() {

std::vector<int> vec = {1, 2, 3, 4, 5};

auto iterator = get_iterator_type(vec);

std::cout << "The first element in the container is: " << *iterator << std::endl;

return 0;

}

Output:

Trailing Return Type C++ 11

Explanation:

  • The template argument T's iterator member type determines the return type.
  • By avoiding repetition, the trailing return type clarifies this dependency.
  • Conditional Return Types:

Selecting Return Type Based on Conditions:

auto create_reference(bool use_ref) -> std::conditional_t<use_ref, int&, int> {

int value = 42;

// ... logic to decide reference or value

return value; // Return type determined based on condition

}
  • The use_ref argument is used to determine the return type at compile time.
  • This conditionality is handled gracefully by the trailing return type.
  • Functions Using decltype for Type Deduction:

Deducing Return Type from Expressions:

template <typename T1, typename T2>

auto add_and_multiply(T1 x, T2 y) -> decltype(x + y * 2) {

return x + y * 2;

}
  • Decltype is used to infer the return type from the returned expression.
  • This type of deduction can be enabled without explicitly writing it out by using the trailing return type.
  • Lambda Expressions:

Specifying Return Types for Lambdas:

#include <iostream>

int main() {

auto even_numbers = [](int x) -> bool {

return x % 2 == 0;

};

// Testing the lambda function

int number = 10;

if (even_numbers(number)) {

std::cout << number << " is even." << std::endl;

} else {

std::cout << number << " is odd." << std::endl;

}

return 0;

}

Output:

Trailing Return Type C++ 11
  • Lambda expressions inherently require trailing return types.

Auto Keyword and Trailing Return Type: A Powerful Combination:

The auto keyword in C++ is essential for enabling return types that trail. Together, they simplify function declarations in the following ways:

  1. auto as a Placeholder:
  2. The auto keyword acts as a stand-in for the actual return type when trailing return types are used; the actual return type is specified later using the trailing return arrow (->).
  3. The compiler should infer the return type from the function's body or other context.
  4. Type Deduction:
  5. The compiler identifies the proper return type by examining how the function is implemented.
  6. Expressions inside the function body are considered during this deduction process, which may employ decltype in more complex situations.
  7. Enhanced Readability:
  8. It is usually easier to read when the return type comes after the parameter list, especially for long or complex types.
  9. It enables you to deal with the parameters and name of the function before addressing the return type.
  10. Flexibility and Conciseness:
  11. When the return type may be variable or unknown, auto in the return type provides flexibility.
  12. It can result in shorter code that does not require long type names to be explicitly written out.

Examples:

Simple Function with Type Deduction:

#include <iostream>

auto add(int x, int y) -> decltype(x + y) {

return x + y; // Compiler deduces return type as int

}

int main() {

int a = 5;

int b = 7;

// Using the add function

auto result = add(a, b);

// Displaying the result

std::cout << "The sum of " << a << " and " << b << " is: " << result << std::endl;

return 0;

}

Output:

Trailing Return Type C++ 11

Template Function with Dependent Return Type:

#include <iostream>

#include <vector>

template <typename T>

auto create_vector(size_t size) -> std::vector<T> {

return std::vector<T>(size);

}

int main() {

auto intVector = create_vector<int>(5);

auto doubleVector = create_vector<double>(8);

std::cout << "Size of intVector: " << intVector.size() << std::endl;

std::cout << "Size of doubleVector: " << doubleVector.size() << std::endl;

return 0;

}

Output:

Trailing Return Type C++ 11

Compatibility and Portability: Navigating the Transition to Trailing Return Types

Although trailing return types have many advantages, you should take compatibility and portability into account before implementing them in your C++ projects:

  1. Compatibility with Older C++ Standards:
  2. Trailing return types are a relatively new addition to the standard.
  3. Not Compatible with Previous Compilers: Compilation errors result from compilers that don't fully support C++11. These compilers won't recognize return types that trail.
  4. Compatibility and Portability:
  5. Discuss how trailing return types work with older standards.
  6. Discuss any possible problems or things to remember while converting code to C++11 and utilizing trailing return types.
  7. Project-Specific Requirements:
  8. Analyze the needs of the project: Examine your project's particular constraints and requirements about the portability and support for the C++ standard.
  9. Select an Adoption Plan: Choose whether to fully embrace trailing return types or use them sparingly after your evaluation.
  10. Potential Issues:
  11. Compiler Support: To prevent incompatibilities, make sure your compiler fully supports C++11.
  12. Code Readability: Developers used to traditional syntax may find trailing return types strange. Give precise instructions and illustrations to make adoption easier.
  13. Debugging: The debugging experience may be impacted by certain debuggers' incorrect display of trailing return types.

Real-World Examples of Trailing Return Types in Action:

Here are some sample code from well-known open-source projects that shows how trailing return types are used in real-world scenarios:

  • Eigen (Linear Algebra Library):
template<typename BinaryOp>

auto cwiseProduct(const MatrixBase<OtherDerived>& other, const BinaryOp& func) const

-> const CwiseBinaryOp<BinaryOp, const Derived, const OtherDerived>

{

return CwiseBinaryOp<BinaryOp, const Derived, const OtherDerived>(derived(), other.derived(), func);

}

Explanation:

  • This example uses a trailing return type when the complex return type of a template function depends on the template arguments.
  • By arranging the return type after the function's parameter list, readability is improved.
  • Boost.Asio (Asynchronous I/O Library):
template <typename CompletionToken>

auto async_read_until(AsyncReadStream& s,

asio::basic_streambuf<Allocator>& b,

char delim, CompletionToken&& token)

-> typename asio::async_result<

typename std::decay<CompletionToken>::type,

void(error_code, std::size_t)>::return_type

{

return asio::async_initiate<CompletionToken,

void(error_code, std::size_t)>(

typename asio::detail::initiate_async_read_until_delim_v1<

AsyncReadStream,

asio::basic_streambuf<Allocator>,

char>::type(), token, s, b, delim);

}

Explanation:

  • This example uses trailing return type for a complex template function involving asynchronous operations.
  • Leverages decltype to deduce the return type based on the completion token, ensuring type safety.
  • Range-v3 (Range Library):
template<typename T>

constexpr auto next(T& t)

-> decltype(std::next(std::declval<T&>()))

{

return std::next(t);

}

Explanation:

  • This example demonstrates how to infer the return type for a range adaptor from the following expression by using decltype and a trailing return type.
  • It makes it easier for generic code to function with different range types.
  • Clang (C++ Compiler Frontend):
template <typename T>

auto make_unique(Args&&... args) -> std::unique_ptr<T> {

return std::unique_ptr<T>(new T(std::forward<Args>(args)...));

}

Explanation:

  • It provides a template function that generates an instance of std::unique_ptr with a trailing return type.
  • It removes the need for the template argument explicitly specified in the return type, improving readability and maintainability.