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++

Fesetround() and Fegetround() in C++ and their application
2023-05-08 23:54:13

Fesetround() and Fegetround() in C++ and their application

Introduction:

Floating-point numbers are used to represent real numbers that can have fractional values. However, there are limitations to the accuracy of floating-point numbers, which can result in errors when performing arithmetic operations. To mitigate this, C++ provides two functions called fesetround() and fegetround() that help in rounding floating-point numbers.

What is fesetround() in C++?

fesetround() is a C++ standard library function that sets the rounding direction for floating-point operations. It takes one argument, which can be one of the following predefined constants:

  • FE_DOWNWARD: Round to the nearest number towards negative infinity.
  • FE_TOWARDZERO: Round to the nearest number toward zero.
  • FE_TONEAREST: Round to the nearest number.
  • FE_UPWARD: Round to the nearest number towards positive infinity.

The default rounding mode for floating-point operations in C++ is FE_TONEAREST. However, in some cases, it may be necessary to use a different rounding mode. For example, in financial applications, it may be necessary to round toward zero or toward negative infinity, depending on the specific requirements of the calculation.

To use fesetround(), you must first include the header file. The syntax for fesetround() is as follows:

#include <cfenv>
int fesetround(int round_mode);

Here, round_mode is the rounding mode you wish to set. It should be one of the predefined constants mentioned above.

The return value of fesetround() is zero if the rounding mode was set successfully and a non-zero value otherwise. If an invalid rounding mode is specified, fesetround() returns a non-zero value and leaves the rounding mode unchanged.

It is important to note that fesetround() affects all floating-point operations after it is called. If you need to change the rounding mode for a specific operation, you can use the std::fesetround() function, which takes a local environment as an argument.

Here is an example program that demonstrates how to use fesetround() in C++ to set the rounding mode for floating-point operations:

#include <iostream>
#include <cmath>


#include <cfenv>


int main() {
    double x = 1.5;
    double y = -1.5;


    // Set rounding mode to "round towards zero."
    std::fesetround(FE_TOWARDZERO);


    // Round x and y to the nearest integer
    double rounded_x = std::round(x);
    double rounded_y = std::round(y);


    // Print the results
    std::cout << "x rounded to the nearest integer: " << rounded_x << std::endl;
    std::cout << "y rounded to the nearest integer: " << rounded_y << std::endl;


    return 0;
}

Explanation:

  • This C++ program demonstrates how to round a floating-point number to the nearest integer using the std::round function and how to set the rounding mode using the std::fesetround function from the header.
  • The program starts by declaring two double variables, x, and y, and initializing them to 1.5 and -1.5, respectively.
  • Next, the rounding mode is set to "round towards zero" using the std::fesetround function with the FE_TOWARDZERO argument.
  • This means that the result of rounding a number that is exactly halfway between two integers will be rounded toward zero (i.e., towards the nearest integer with a smaller absolute value).
  • Then, the program calls the std::round function to round x and y to the nearest integer. The std::round function takes a double argument and returns the nearest integer as a double value.
  • Finally, the program prints the rounded values of x and y using std::cout.

Program output:

Fesetround() and Fegetround() in C++ and Their application

What is fegetround() in C++?

fegetround() is a C++ standard library function that returns the current rounding mode for floating-point operations. It takes no arguments and returns one of the following predefined constants:

  • FE_DOWNWARD: Round to the nearest number towards negative infinity.
  • FE_TOWARDZERO: Round to the nearest number toward zero.
  • FE_TONEAREST: Round to the nearest number.
  • FE_UPWARD: Round to the nearest number towards positive infinity.

The default rounding mode for floating-point operations in C++ is FE_TONEAREST. However, in some cases, it may be necessary to determine the current rounding mode. For example, if your application requires precise rounding, you may want to verify that the correct rounding mode is being used.

To use fegetround(), you must first include the <cfenv> header file. The syntax for fegetround() is as follows:

#include <cfenv>
int fegetround();

The return value of fegetround() is the current rounding mode, as one of the predefined constants mentioned above.

It is important to note that fegetround() returns the rounding mode for the current environment. If you need to determine the rounding mode for a specific operation, you can use the std::fegetround() function, which takes a local environment as an argument.

Here is an example program that demonstrates the use of fegetround() in C++ to retrieve the current rounding mode for floating-point operations:

#include <iostream>
#include <cfenv>


int main() {
    // Get the current rounding mode
    int current_rounding_mode = std::fegetround();


    // Print the current rounding mode
    if (current_rounding_mode == FE_DOWNWARD) {
        std::cout << "The current rounding mode is FE_DOWNWARD" << std::endl;
    } else if (current_rounding_mode == FE_TOWARDZERO) {
        std::cout << "The current rounding mode is FE_TOWARDZERO" << std::endl;
    } else if (current_rounding_mode == FE_TONEAREST) {
        std::cout << "The current rounding mode is FE_TONEAREST" << std::endl;
    } else if (current_rounding_mode == FE_UPWARD) {
        std::cout << "The current rounding mode is FE_UPWARD" << std::endl;
    } else {
        std::cout << "Unknown rounding mode" << std::endl;
    }


    return 0;
}

Explanation:

  • The main function of the program starts by declaring an integer variable called "current_rounding_mode". The value of this variable will later be set to the current rounding mode.
  • Next, the program uses the "fegetround" function from the "cfenv" library to get the current rounding mode. This function returns an integer value that represents the current rounding mode.
  • The program then checks the value of the "current_rounding_mode" variable to determine which rounding mode is currently being used.
  • If the value is FE_DOWNWARD, the program prints "The current rounding mode is FE_DOWNWARD" to the console.
  • If the value is FE_TOWARDZERO, the program prints "The current rounding mode is FE_TOWARDZERO" to the console.
  • If the value is FE_TONEAREST, the program prints "The current rounding mode is FE_TONEAREST" to the console.
  • If the value is FE_UPWARD, the program prints "The current rounding mode is FE_UPWARD" to the console.
  • If the value is none of these values, the program prints "Unknown rounding mode" to the console.

Program Output:

Fesetround() and Fegetround() in C++ and Their application

Application of fesetround() and fegetround():

The main application of fesetround() and fegetround() is to control the rounding behavior of floating-point operations in C++. This is particularly useful in cases where precise rounding is required, such as in financial applications. The following are some examples of their usage:

Financial Applications:

In financial applications, rounding errors can have a significant impact on calculations. For example, when calculating interest rates, even a small rounding error can lead to a significant difference in the final result. In such cases, it is necessary to use precise rounding methods. fesetround() and fegetround() can be used to ensure that the correct rounding method is used.

Graphics Applications:

In graphics applications, floating-point numbers are used to represent positions and orientations of objects. In such cases, rounding errors can result in visual artifacts, such as flickering or jagged edges. By using fesetround() and fegetround(), the rounding behavior can be controlled to reduce these artifacts.

Scientific Applications:

In scientific applications, floating-point numbers are used to represent physical quantities. In some cases, rounding errors can lead to incorrect results, which can have serious consequences. For example, in simulations of physical systems, rounding errors can cause the simulation to diverge from reality. By using fesetround() and fegetround(), the rounding behavior can be controlled to ensure that the simulation is as accurate as possible.

Conclusion:

In conclusion, fesetround() and fegetround() are C++ functions that are used to set and retrieve the rounding mode for floating-point arithmetic operations. They are part of the <cfenv> header and provide a way to ensure that arithmetic operations are performed consistently across different platforms and compilers.

The applications of fesetround() and fegetround() are numerous and include financial calculations, numerical simulations, optimization algorithms, and cryptography. In these applications, the choice of rounding mode can affect the accuracy, stability, and security of the calculations, making it important to use a consistent rounding mode throughout the computation.

Overall, fesetround() and fegetround() provide a flexible and efficient way to control the rounding mode in floating-point arithmetic, which is important in many applications where numerical accuracy and consistency are critical.