CPP preprocessor Directives

What is CPP preprocessor Directives?

Imagine you're baking a cake. Before you put the cake in the oven, you might prepare the ingredients and do some setup. In C++ programming, the preprocessor is like that preparation phase before your code is actually turned into a program.

Preprocessor directives are special commands that start with a # symbol. They tell the preprocessor what to do with your code before it's compiled (turned into a program that a computer can understand).

• We can use CPP preprocessor directives anywhere in our program.
• #include is a preprocessor directive that includes the contents of the <iostream> and other header file into your C++ program.
• when we include something at the top of the code is called "HEADER FILE".
• The <iostream> is C++ Standard Library and allows you to perform console-based input and output operations using the cin and cout streams, as well as other stream-related operations.

HEADER FILE

• Header files should be declared at the top of your source code files.
• Including header files at the beginning of your code ensures that the declarations and definitions from those headers are available to the rest of your code that follows.

#include <iostream> // Example header file

// Other header file inclusions
#include "myheader.h"

// Function and class declarations

int main() {
    // Your program's logic

    return 0;
}

// Function and class definitions

C++ Standard Library

• The header file is part of the C++ Standard Library.
• It provides the necessary declarations and definitions for input and output operations, such as reading from the standard input (keyboard) and writing to the standard output (console).
• This header is an essential part of C++ programming, as it allows you to work with input and output streams, such as cin (for reading input) and cout (for writing output). The << and >> operators are commonly used with these streams for formatted input and output.
• In summary, #include <iostream> is used to include the input/output stream header in your C++ program, allowing you to perform console-based input and output operations. It's a fundamental aspect of C++ programming for interacting with the user and displaying information.

Here are some C++ standard library

• <vector>: Provides the std::vector container, which is a dynamic array that can resize itself. It's commonly used for storing collections of elements.
• <string>: Provides the std::string class for working with strings in C++. It offers various string manipulation functions.
• <map> and <unordered_map>: Provide the std::map and std::unordered_map containers for associative arrays (key-value pairs).
• <array>: Introduces the std::array container, representing a fixed-size array with type safety and helpful functions.
• <list>: Provides the std::list container, which is a doubly-linked list.
• <queue>: Offers various queue-related data structures like std::queue and std::priority_queue.
• <stack>: Defines the std::stack container, representing a stack data structure.
• <cmath>: Provides mathematical functions like sqrt, sin, cos, and others. It's part of the C++ Standard Library's math functions.
• <fstream>: Provides classes for working with files, including input and output file streams (ifstream and ofstream), which allow reading from and writing to files.
• <algorithm>: Provides a collection of algorithms like sort, find, and others for working with collections (like arrays or vectors) efficiently.
• <ctime>: Provides functions and types related to date and time manipulation.
• <cstdlib>: Provides general-purpose functions, including memory allocation, random number generation, and other utility functions.
• <stdexcept>: Provides standard exception classes like std::runtime_error, which can be used to handle exceptional situations in your program.
• <cstdio>: Provides functions for working with C-style file I/O (input/output) operations.
• <iomanip>: Provides facilities for formatting input and output, including setting precision, alignment, and other formatting options.

These are the one that I've used up untill now

• <string>: Provides the std::string class for working with strings in C++. It offers various string manipulation functions.
• <iostrearm>