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Topics

C++ Basics

Introduction to C++C++ History and EvolutionC++ Environment SetupC++ First ProgramC++ SyntaxC++ CommentsC++ Data TypesC++ VariablesC++ ConstantsC++ KeywordsC++ OperatorsC++ Input/Output

C++ Control Structures

C++ If-Else StatementsC++ Switch StatementsC++ For LoopsC++ While LoopsC++ Do-While LoopsC++ Break and ContinueC++ Goto Statement

C++ Functions

C++ Function BasicsC++ Function ParametersC++ Function OverloadingC++ Inline FunctionsC++ RecursionC++ Default ArgumentsC++ Lambda Expressions

C++ Arrays and Strings

C++ ArraysC++ Multidimensional ArraysC++ C-style StringsC++ String ClassC++ String FunctionsC++ String Streams

C++ Pointers and References

C++ Pointers BasicsC++ Pointer ArithmeticC++ ReferencesC++ Pointers vs ReferencesC++ Dynamic Memory AllocationC++ Smart Pointers

C++ Object-Oriented Programming

C++ Classes and ObjectsC++ Constructors and DestructorsC++ Access SpecifiersC++ EncapsulationC++ InheritanceC++ PolymorphismC++ Virtual FunctionsC++ Abstract ClassesC++ Interfaces (Pure Virtual)C++ Friend Functions and Classes

C++ Templates

C++ Function TemplatesC++ Class TemplatesC++ Template SpecializationC++ Variadic Templates

C++ Exception Handling

C++ Try-Catch BlocksC++ Throwing ExceptionsC++ Custom ExceptionsC++ Exception Specifications

C++ File Handling

C++ File I/O StreamsC++ Reading from FilesC++ Writing to FilesC++ Binary File Operations

C++ Standard Template Library

C++ STL ContainersC++ STL AlgorithmsC++ STL IteratorsC++ STL Function Objects

C++ Advanced Topics

C++ NamespacesC++ Preprocessor DirectivesC++ Type CastingC++ MultithreadingC++ Regular ExpressionsC++ Move SemanticsC++ Rvalue References

C++ Memory Management

C++ Stack vs HeapC++ Memory LeaksC++ Garbage CollectionC++ Custom Allocators

C++ Best Practices

C++ Coding StandardsC++ Performance OptimizationC++ Debugging TechniquesC++ Unit Testing

C++ Input and Output Operations

Input and output (I/O) operations are fundamental to any programming language. In C++, these operations are handled through streams, providing a flexible and efficient way to interact with users and files.

Standard I/O Streams

C++ uses the iostream library to manage input and output. This library defines three standard streams:

  • cin: Standard input stream
  • cout: Standard output stream
  • cerr: Standard error stream (unbuffered)

Output with cout

The cout object is used for output. It's typically paired with the insertion operator (<<) to display text and variables.


#include <iostream>
using namespace std;

int main() {
    int age = 25;
    cout << "My age is: " << age << endl;
    return 0;
}

This example demonstrates how to output a string and an integer variable. The endl manipulator adds a newline and flushes the output buffer.

Input with cin

For input, C++ uses the cin object along with the extraction operator (>>). This allows you to read values from the standard input.


#include <iostream>
#include <string>
using namespace std;

int main() {
    string name;
    int age;

    cout << "Enter your name: ";
    cin >> name;

    cout << "Enter your age: ";
    cin >> age;

    cout << "Hello, " << name << "! You are " << age << " years old." << endl;
    return 0;
}

This example shows how to read a string and an integer from the user. The program then uses cout to display the entered information.

I/O Manipulators

C++ provides various manipulators to format output. These are used with the insertion and extraction operators to modify how data is displayed or read.

Common Manipulators:

  • endl: Inserts a newline character and flushes the stream
  • setw(int n): Sets the field width for the next input/output operation
  • setprecision(int n): Sets the decimal precision for floating-point values
  • fixed: Uses fixed-point notation for floating-point values

To use these manipulators, include the <iomanip> header.


#include <iostream>
#include <iomanip>
using namespace std;

int main() {
    double pi = 3.14159265359;
    cout << fixed << setprecision(2);
    cout << "Pi to 2 decimal places: " << pi << endl;
    return 0;
}

This example demonstrates how to use manipulators to format the output of a floating-point number.

File I/O

C++ also supports file input and output operations using the fstream library. This allows you to read from and write to files, expanding the capabilities of your programs.

For more information on file operations, check out the guide on C++ File I/O Streams.

Best Practices

  • Always check if input operations were successful before using the read values.
  • Use appropriate manipulators to format output for better readability.
  • Consider using cerr for error messages instead of cout.
  • When dealing with large amounts of output, consider using cout.flush() to manually flush the output buffer.

Understanding I/O operations is crucial for creating interactive C++ programs. As you advance, explore more complex I/O techniques and consider how they integrate with other C++ features like classes and objects for more sophisticated program designs.