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Lubna Fathima
Lubna Fathima

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Introduction to C++ : Part 1

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 h*igh 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;
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  • 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; 
    ... 
}
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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
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For compiling and running a CPP program in Windows following are the command lines:

Compile: gcc Filename.cpp 
Run or execute: filename
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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     */
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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    */
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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    */
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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    */
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If you have read this far... Do not forget to stay tuned for Part 2 of this series.

Thank you for reading 👋

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