The Difference Between C and C++

What Is the C Programming Language?

Dennis Ritchie designed the C programming language in 1972 at Bell Laboratories. The C language is the base language for many object-oriented programming languages like C++, a superset of C language, and Java, an extension of the C++ language. This language was originally developed to write and develop programs to build operating systems. UNIX OS and all of its programs and utilities are originally written in C. Furthermore, the use of the C language extended to develop applications like compilers, text editors, assemblers, drivers, databases, and other utility programs.

The C language is based on the paradigm of “Procedural Programming”. This means that this programming language focuses more on procedure than data. You will look into all aspects of the approaches used by C and C++ when explaining the difference between C and C++, in this article. 

As mentioned above, since the procedural programming principle emphasizes procedure more than data, many problems arose because of this, especially with extending software and maintaining them. That’s where its successor C++ came into the picture. It gives prime consideration to the data and associated functions in it. Also, you can not use the C language along with other generic programming languages.

You can understand the limitations that were encountered by the procedural nature of the C language with the help of a real-life example. You cannot use the C programming language for describing the real world very well. For example,  a vehicle is an object which can act in the real world. However, the procedural language would just be concerned about the procedure (i.e. doing things), so it would just focus on the movement and not care about how the vehicle looks. You can easily distinguish between the real-world interpretation of a vehicle and procedural programming’s interpretation of the same vehicle.

Let’s consider the below example to get an idea of what problems are led by the procedural programming paradigm of C. The following program reads the details of a student like a roll number, name, and the class of a student. 

#include<stdio.h>

typedef struct

{

    int roll;

    char name[25];

    char branch;

}student;

void readStudent(student s1)

{

    printf("Enter roll no. : \n");

    scanf("%d",&s1.roll);

   printf("\nEnter name : \n");

    scanf("%s",s1.name);

    printf("\nEnter class : \n");

    scanf("%s",&s1.branch);

  printf("\nThe student with roll number %d is in branch %c\n", s1.roll, s1.branch);

}

 void main()

{

    student s1;

    readStudent(s1);

    printf("\n");

}

Here, if you observe, due to the change in the basic structure, the student structure has to store marks and grades as well. The structure now modifies to- 

typedef struct 

{

    int roll; 

    char name[25];

    Char branch;

    float marks;

    char grade;

}student;

Now every function acting upon the structure student should also be modified to accommodate the change in structure. Thus, readStudent() needs to be rewritten. Similarly, if five other functions are using or manipulating student in one or another way, it must also modify them to accommodate the changes introduced in structure.

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This means the C programming language is susceptible to design changes. Before jumping into discussing the differences between C and C++, first, understand some important concepts that are not there in C but are supported by C++. 

What Is the C++ Programming Language?

The C++ programming language was developed at AT&T Bell Laboratories in the early 1980s by Bjarne Stroustrup. He found that the ‘C’ language to be lacking in certain sections and decided to extend the language by adding features from the very first OOP language developed by him, Simula 67. 

The C++ programming language is based on the paradigm of Object-Oriented Programming (OOPs). Object-Oriented Programming is an umbrella under which the features of Object-Based programming resides. Meaning, it comprises all the characteristics of object-based programming and gets the better of its limitations by executing inheritance so that through programming, you can solve the problems based on real-life situations. Object-oriented programming has been created to get better at the drawbacks of usual programming techniques. The OOPs method has been developed on some concepts that make it achieve its aim of getting the better of the drawbacks or deficiency of usual programming techniques. 

Before diving deep into C++, you have to learn about the basic concepts of OOPs that are the pillars of C++:

• Data Abstraction:

Abstraction refers to the concept of giving access to only those details that are required to perform a specific task, giving no access to the internal details of that task.

You can understand it better with an example. 

To drive a car, you need to understand how to move the handle, how to operate the clutch, brake and accelerator, and so on. However, it isn’t essential for you to know how the engine works, clutch wired is wired and other deeper aspects of the vehicle. For example, when you change the gears or apply the brakes, the internal mechanism of what transpires is not visible to you. This concept is known as Abstraction, where you know only the basic knowledge required to drive the car without needing to understand the internal mechanism of the vehicle.

• Data Encapsulation:

Data Encapsulation is one of the most important notions of OOPS. It is the way of binding both data and the functions that get executed on the given data under a single roof. These functions are member functions in C++. You do not have permission to access the data directly. Create a member function, to manipulate or use that given data. However, you do not have permission to access the data directly. This data is not visible to you, so it is safe from any kind of manipulation done by an outsider. Data and its member functions are said to be encapsulated in a single cell.

• Modularity:

Modularity is the technique of dividing the program into subprograms or functions. The advantages that modularity can attain are:

• It decreases the complex nature of the article. 
• It generates various well-structured documentation, increasing the quality of the program.

A module is a separate unit in itself. Hence you can execute a separate module as it is connected to other modules in some manner. All the modules act together as a single unit to achieve the aim of the program. In OOPs, classes and objects form the basic foundation of a system. 

• Inheritance:

Understanding inheritance is critical for understanding the whole point behind object-oriented programming. Inheritance in C++ has made it possible to use reusability as a tool to write clean and efficient programs. It also allows the addition of additional features to an existing class without the need to modify it in any way. Inheritance is transitive in nature, which efficiently benefits from the implementation of inheriting the properties of one class by another class.

• Polymorphism:

Polymorphism is the key to the power of object-oriented programming. Polymorphism is the notion that can hold up the ability of an object of a class to show different behavior in response to a message or action. For a language considered to be OOP language, it must support polymorphism.

Now, after discussing the object-oriented concepts which are the base of the C++ programming language, understand how C++ overcomes the problem faced in the C program discussed above. It reads the details of students, with the help of the following C++ implementation using an object-oriented approach.

class student

{

    int roll;               /*************************/

    char name[25];          /** This remains hidden **/

    int branch;               /*************************/  

public:

    void readStudent();     /*******************************/

                            /** This makes user interface **/

    void dispStudent();     /*******************************/

};

Now if you need to include one more field grade in student, then the class would become as:

class student

{

    int roll;               /***********************************/

    char name[25];          /** See, the changes have occured **/

    int branch;               /***** only in the hidden part *****/ 

    char grade;             /***********************************/  

public:

    void readStudent();     /*********************************/

                            /** User interface remains same **/

    void dispStudent();     /*********************************/

};

Now the users continue to get the same interface, unaware of the fact that a new field has been added. There would be some changes in the codes of some of the functions (eg. dispStudent()) by the programmer, but the user cannot access the data of the class student directly which was possible in the above C program. 

The following features and properties of C and C++ will make it easier to understand the difference between C and C++ and will give you a good idea of the uses of both of the languages.

Key Features and Properties of C

The C programming language is originally based on the principle of Procedural Programming. This programming language consists of features that make it suitable for writing programs to develop operating systems, compilers, assemblers, drivers, and a lot more. In this section, you will see those useful key features/properties of the C programming language: 

• Structural or Procedural Programming:

Being a procedural programming language, C lays more emphasis on procedure and steps, than the data.  This makes it a perfect candidate for general-purpose programming. This also enables it to consume less memory and allows the functions to share the same data via global variables. However, this can also expose your data, which you will explore further in the article in the section that talks about the difference between C and C++. 

• Modularity Because of the Rich In-Built Library:

The C programming language has its own library, which consists of a good number of pre-defined functions that can be used by the programmers to simplify the code and ease up their tasks. 

Below is an example to illustrate this property of C:

#include <stdio.h>

#include <math.h>    // header file for sqrt function

                     // used below

void main()

{

   int num, result;

   printf("Enter a number: ");

   scanf("%d", &num);

   // in-built function to calculate

   // square-root of a number

   result = sqrt(num);

   printf("Square root of %.2d = %.2d", num, result);

}

• Fast and Clean:

As in this programming language, handling of garbage collection, memory leaks, and static variables all have to be taken care of manually, which avoids any kind of additional processing, which is there in other programming languages. So, this ultimately makes C a very fast and efficient programming language. 

• Portable and Hardware-Independent:

A program written in C language, can be executed and run on any other machine without the need for any sort of modification in the code, which makes it highly portable and machine-independent.

• Foundation for Many Other Programming Languages:

C provides the foundation and base for many modern programming languages like C++ and Java, which are extensions to C. This language does not contain the concepts like OOPS and garbage collection, however, many programming languages are a superset of C.

• Intermediate-Level Language:

C has the abilities of an assembly-level language and the features of a high-level language.

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Key Features/Properties of C++

The C++ programming language is based on the paradigm of Object-Oriented Programming (OOPs). The programming paradigm is the major difference between C and C++ that separates them in a great way. C++ is a superset of the C language which means that it includes all the features of C and overcomes its limitations by implementing some new concepts. In this section, you are going to see some key features/properties of C++ which also highlights the difference between C and C++:

• Object-Oriented Programming:

The C++ programming language is based on the paradigm of Object-Oriented Programming (OOPs). OOP is a technique for writing a program in which the data and behavior are bound with each other under the same umbrella i.e., encapsulated together as classes whose instances are objects.

The OOPs approach is based on certain concepts that help it attain its goal of overcoming the drawbacks or shortcomings of conventional programming approaches. The basic concepts of OOPs are:

• Data Abstraction

• Data Encapsulation

• Modularity

• Inheritance

• Polymorphism

• Ease of Maintenance:

C++ provides ease of maintenance and fabrication due to the structure and base it is developed on. The concepts such as modularity, polymorphism allow programs with better readability. This also helps to reduce down the search for problems.

• Re-Use of Code:

C++ allows its users to re-use the code. Encapsulation enables the class methods to be re-used in other functions of the code. This also increases the readability of code since the replication of code has been reduced to almost zero.

• Auto Keyword:

The auto keyword is introduced in C++ so that the user does not have to declare the data type every time during compilation. But you have to keep in mind while using the auto keyword, that the variable that has been declared using auto should be declared and initialized at the same time. 

Below is an example to illustrate this property of C++:

#include<iostream>

using namespace std;

int autoExample(int n1, int n2)

{

    return n1 * n2;

}

int main()

{

    // autoExample() returns an int value, 

    // so the type of the variable "product" will be 

    // deduced to int.

   auto product { autoExample(10, 20) }; 

    cout << product << "\n\n";

    return 0;

}

• Memory Management:

Apart from the static allocation of memory, C++ also supports Dynamic Memory Allocation. When you allocate the memory in run time, it is known as dynamic memory allocation. You can create such a memory by using the new keyword. In other OOP languages like Java and Python, memory allocated dynamically gets automatically deleted or gets deallocated once it’s of no use. But in C++, the user has to delete the memory manually. This can be achieved by using the delete keyword.

Below is an example to illustrate this property of C++:

#include <iostream>

using namespace std; 

int main()

{

    // declaring a pointer to hold address

    // of an int type value.

    int* num;

    // allocate dynamic memory for the pointer.

    num = new int;      // new keyword

    *num = 100;

    cout << "Num is storing to the address of : ";

    cout << *num << "\n\n";

    // deallocate the memory

    delete num;         // delete keyword

}

• Ease of Comprehension:

You can set the classes up to closely represent the generic application concepts and processes. OOP codes are nearer to real-world models than the other programming methodologies’ codes.

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Difference Between C and C++

The concepts discussed above are briefly summarised to clearly highlight the major difference between C and C++.

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Conclusion

In this article, you have learned the difference between C and C++. This article talked about C and C++ in-depth and dived deep into the key features of both programming languages. You saw in detail what Object-Oriented Programming is, and how it has overcome the inferiorities of procedural programming. 

To get a better understanding of the entire C and C++ programming languages, you can go through our guide in C++ Programming for Beginners and What is C Programming? To get a better understanding of Object-Oriented Programming concepts, you can learn Java programming language by enrolling in Simplilearn’s Java Certification Training Course. 

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