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++

C++ Forward Iterators

Iterators :

Iterators serve as a link between algorithms and STL containers, allowing the data inside the container to be modified. They let you to iterate through the container, access and assign values, and apply various operators to them in order to get the required outcome.

Forward Iterators :

Both of the input and output iterators are served by forward iterators. As a result, these iterators are called input-output operators. The values may be accessed (input iterator’s functionality) as well as assigned (functionality of output iterators). In one-way iterators, as their name implies, only forward movement is allowed. Additionally, Bidirectional and Random access iterators are valid forward iterators. In C++, the Forward Iterator can be used to read and write to a container, hence it can be claimed that the forward iterator is essentially a mix of the Forward and Random Access iterators. Forward iterators are commonly used to read the contents of a container from the start to end.

The forward iterator uses just the increment operator (++) to traverse all of the items of a container. In C++, a forward iterator is sometimes referred to as a multi-pass iterator.

Operations on Forward Iterators :

The following is a list of operations that are commonly performed on forward iterators :

  • The forward iterator is usually constructible by default.

Expression :

A i;
  • In most cases, the forward iterator can be copied.

Expression :

A i(j);
  • In most cases, the forward iterator can be copied.

Expression :

j = i;
  • In general, an equality or inequality operator can be used to compare the forward iterator.

Expression :

x++;
++x
  • In general, the forward iterator can be increased.

Expression :

x++;
++x
  • In most cases, a forward iterator may be dereferenced as a lvalue.

Expression :

*x=t;
  • In most cases, a forward iterator can be dereferenced to a rvalue.

Expression :

*x;

In the demonstration above, 'A' represents a forward iterator type, i and j represent forward iterator type objects, and t represents an object that has been directed by the iterator type object.

Features of the Forward Iterators :

The following are some of the characteristics of forward iterators:

Equality/Inequality operator :

The forward iterator may be compared simply by utilizing an equality or inequality operator.

Dereferencing :

The forward iterator may be dereferenced for both these values, such as a lvalue and a rvalue, and coders can allocate the value to the output iterator and give a value to it.

Incrementable :

The forward iterator can be incremented, but it can't be decremented.

Example of Forward Iterator in C++ :

#include <iostream>
#include <vector>
using namespace std;
int main()
{	// Declaring a vector vect1
	vector<int> vect1 = { 10, 20, 30, 40, 50 };


	// Declaring the iterator itr1
	vector<int>::iterator itr1;


	for (itr1 = vect1.begin(); itr1 != vect1.end(); ++itr1) {
		// Assigning the values to the locations that are pointed by the iterator
		*itr1 = 10;
	}


	for (itr1 = vect1.begin(); itr1 != vect1.end(); ++itr1) {
		// Accessing the values at the locations that are pointed by the iterator
		cout << (*itr1) << " ";
	}


	return 0;
}

Output :

10 10 10 10 10

Explanation :

In the above example, we declared a vector list called vect1 and an iterator called itr1. Then we assigned the values to the locations that were pointed by the iterator pointer. After that, we accessed the values at the locations that were pointed by the iterator pointer. As we can see, the iterator may be accessed as well as assigned a value, indicating that it is at least a forward iterator which can be any element in the hierarchy.

Drawbacks of Forward Iterator :

The following are the limits that are applicable to the Forward Iterator in general:

  • Relational operator :
    Users can utilize an equality with the forward iterator in most cases, but the constraint is that the other iterators would not be applied to the forward iterator in C++.
  • Arithmetic operator:
    The forward iterator does not support this sort of operator.
  • Decrementable :
    Because the forward iterator only advances forward, it is not feasible to increment it.
  • Random Access :
    The forward iterator can only iterate across the items in a container, therefore random access to an element is not feasible.
  • Unidirectional :
    These iterators are unidirectional, as previously stated. They can only move ahead, that is, they can only be increased. You can't take anything away from them.
  • Offset Dereference Operator ([]) :
    The forward iterators do not support the offset dereference operator ([]). As a result, the offset operator cannot be used to dereference a forward iterator.



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