Introduction to C++

Introduction, Features and Uses of C++

Introduction

• C++ is a general-purpose programming language and is widely used nowadays for competitive programming.

• It has imperative, object-oriented, and generic programming features.

• C++ runs on lots of platforms like Windows, Linux, Unix, Mac, etc.

• It can be used to develop operating systems, browsers, games, and so on.

• This makes C++ powerful as well as flexible.

• You can run programs and practice them on your local desktop, Using one of these compilers: Code blocks, VS Code, Dev C++, Atom, and many more.

Features of C++

• Simple

• Portability

• Powerful and Fast

• Rich Library

• Platform Dependent

• Mid-level programming language

• Structured programming language

• Object-Oriented

• Case Sensitive

• Compiler Based

• Syntax based language

• Pointers

• Dynamic Memory Management

Simple:

• C++ is a simple language because it provides a structured approach (to break the problem into parts), a rich set of library functions, data types, etc.

• It allows us to follow both procedural as well as functional approaches to design our flow of control.

Portability:

• It is the concept of carrying the instruction from one system to another system.

• In C++ language .cpp file contains source code, and we can also edit this code.

• .exe file contains the application, which is the only file that can be executed. W

• When we write and compile any C++ program on the Windows operating system, it efficiently runs on other window-based systems.

Powerful:

• C++ is a very powerful programming language, and it has a wide variety of data types, functions, control statements, decision-making statements, etc.

• C++ is a fast language as compilation and execution time is less.

• Also, it has a wide variety of data types, functions & operators.

Rich Library:

• C++ library is full of in-built functions that save a tremendous amount of time in the software development process.

• As it contains almost all kinds of functionality, a programmer can need it in the development process.

• Hence, saving time and increasing development speed.

Platform Dependent:

• Platform-dependent language means the language in which programs can be executed only on the operating system where it is developed & compiled.

• It cannot run or execute on any other operating system. E.g., compiled programs on Linux won’t run on Windows.

Mid-level programming language:

• C++ can do both low-level & high-level programming.

• That is the reason why C++ is known as a mid-level programming language.

Structured programming language:

• C++ is a structured programming language as it allows to break off of the program into parts using functions.

• So, it is easy to understand and modify.

Object-oriented:

• C++ is an object-oriented programming language.

• OOPs make development and maintenance easier.

• whereas, in Procedure-oriented programming language, it is not easy to manage if code grows as project size grows.

• It follows the concept of oops like polymorphism, inheritance, encapsulation, abstraction.

Case sensitive:

• C++ is a case-sensitive programming language.

• In C++ programming, 'break and BREAK' both are different.

Compiler-Based:

• C++ is a compiler-based language, unlike Python.

• C++ programs used to be compiled, and their executable file is used to run it due to which C++ is a relatively faster language than Java and Python.

Syntax-based language:

• C++ is a strongly typed syntax-based programming language.

• If any language follows the rules and regulations strictly, it is known as a strongly syntax-based language.

• Other examples of syntax-based languages are C, C++, Java, .net etc.

Pointer:

• C++ supports pointers that allow the user to deal directly with the memory and control the programmer.

• This makes it very suitable for low-level tasks and very complicated projects.

• It is known to increase the speed of execution by decreasing the memory access overhead.

Dynamic Memory Management:

• It supports the feature of dynamic memory allocation.

• In C++ language, we can free the allocated memory by calling the free() function.

• These features are missing in languages like C.

Uses of C++

There are several benefits of using C++ because of its features and security.

below are some uses of C++ Programming Language

Operating Systems:

• One of the key requirements of an Operating System is that it should be very fast as it is responsible for scheduling and running the user programs.

• The strongly typed and fast nature of C++ makes it an ideal candidate for writing operating systems.

• Also, C++ has a vast collection of system-level functions that also help in writing low-level programs.

• Microsoft Windows or Mac OS X, or Linux all operating systems have some parts programmed in C++.

Games:

• Again since most, games need to be faster to support smooth gameplay, C++ is extensively used in game design.

• C++ can easily manipulate hardware resources, and it can also provide procedural programming for CPU-intensive functions.

Browsers:

• With the fast performance of C++, most browsers have their rendering software written in C++.

• Browsers are mostly used in C++ for rendering purposes. Rendering engines need to be faster in execution as most people do not like to wait for the web page to be loaded.

Libraries:

• Many high-level libraries use C++ as the core programming language.

• For example, TensorFlow uses C++ as the back-end programming language.

• Such libraries required high-performance computations because they involve multiplications of huge matrices to train Machine Learning models.

• As a result, performance becomes critical.

• C++ comes to the rescue in such libraries.

Graphics:

• C++ is widely used in almost all graphics applications that require fast rendering, image processing, real-time physics, and mobile sensors.

Cloud/Distributed Systems:

• Cloud storage systems use scalable file systems that work close to the hardware.

• Also, the multi-threading libraries in C++ provide high concurrency and load tolerance.

Embedded Systems:

• C++ is closer to the hardware level, and so it is quite useful in embedded systems as the software and hardware in these are closely coupled.

• Many embedded systems use C++, Such as smartwatches, MP3 players, GPS systems, etc.

Compilers:

• Compilers of various programming languages use C++ as the back-end programming language.

How to implement a code in C++

Headers in C++

• C++ code begins with the inclusion of header files.

• There are many header files available in the C++ programming language.

• So, what are these header files? The names of program elements such as variables, functions, classes, and so on must be declared before they can be used.

• For example, you can’t just write x = 42 without first declaring variable x as:

    int x = 42;
  

  The declaration tells the compiler whether the element is an int, a double, a float, a function, or a class.

  Similarly, header files allow us to put declarations in one location and then import them wherever we need them.

  This saves a lot of typing in multi-file programs.

  To declare a header file, we use the #include directive in every .cpp file.

  This #include is used to ensure that they are not inserted multiple times into a single .cpp file.

  Now, moving forward to the code:

#include <iostream>
using namespace std;

• iostream stands for Input/Output stream, meaning this header file is necessary to take input through the user or print output to the screen. This header file contains the definitions for the functions:

  • cin: used to take input

  • cout: used to print output

• namespace defines which input/output form is to be used. You will understand these better as you progress in the course.

• Note: semicolon (;) is used for terminating a C++ statement. i.e., different statements in a C++ program are separated by a semicolon.

main() function

int main() { 
    Statement 1; 
    Statement 2; 
    ... 
}

int main()

• int: This is the return type of the function. You will get this thing clear once you learn about Functions.

• main(): This is the portion of any C++ code inside which all the commands are written and executed.

  • This is the line at which the program will begin executing. This statement is similar to the start block of flowcharts.

• {}: All the code written inside the curly braces is said to be in one block, also known as a particular function scope. Again, things will be clear once you learn about Functions

Compiler and Run

For compiling and running a CPP program in Linux following are the command lines:

Compile: g++ Filename.cpp 
Run or execute: ./a.out

For compiling and running a CPP program in Windows following are the command lines:

Compile: gcc Filename.cpp 
Run or execute: filename

Macros and Comments in C++

Macros in C++

• Macros are a piece of code in a program that is given some name.

• Whenever the compiler encounters this name, the compiler replaces the name with the actual piece of code.

• The '#define' directive is used to define a macro.

• Note: There is no semicolon(:) at the end of the macro definition.

#include <iostream>
using names pace std;
//macro definition
#define LIMIT 5

int main() {
    for (int i 0; i < LIMIT; i++) {
        cout << i <<" ";
    }
    return 0;
}
/*    Output:
      e1 2 3 4     */

Macros with arguments:

• We can also pass arguments to macros.

• Macros defined with arguments work similarly as functions. Example:

#include 
using namespace Std;
// macrO wth parameter 
#define Area(l, b)(* b) 
int main() {
    int l = 10, b =5, a;
    a = Area(1, b); 
    cout << "The Area of the rectangle is: " << a; 
    return 0;
}
/*    Output:
      The area of the rectangle is: 50    */

Comments in C++

• C++ comments are hints that a programmer can add to make their code easier to read and understand.

• They are completely ignored by C++ compilers.

There are two ways to add comments to code:

• // - Single Line Comment

• /* */ - Multi-line Comments

Example: Single-line comment

 #include <iostream>
using namespace std;
int main() {
    // This is a comment 
    cout << "Hello World! "; 
    return 0;
}

/*    Output:
      Hello World    */

Example: Multi-line comment

 #include <iostream>
using namespace std;
int main() {
    /* This is a comment will print
    Hello World*/
    cout << "Hello World! "; 
    return 0;
}

/*    Output:
      Hello World    */

If you have read this far... Do not forget to stay tuned for Part 2 of this series.
Thank you for reading 👋