10 Differences Between C and C++
As the name suggests, the C++ language is an extension of the original language C. When abilities like object-oriented programming, inheritance, polymorphism, abstraction and encapsulation (just to name a few) were introduced into the original C language, the new derivative came to be known as C++. In this blog post we are going to learn the 10 fundamental differences between C and C++.
Background of the C programming language
The C programming language was developed by Dennis Ritchie in 1972 when he worked at the Bell Laboratories of AT&T. Consequently, he came to be known as the founder of the C language.
Although before seen multiple languages were being used to write programs, it wasn’t as capable as something needed by what Dennis Ritchie was working on. It was developed to work on the UNIX operating system. Originally it was derived from the type less language BCPL, soon it carved its own space, especially when it evolved its very own type structure.
Before C and other languages of its creed, most of the code was written in assembly language. Each state in assembly language corresponded to a single machine code instruction. This low level instruction could only be implicitly understood by a certain computer processor. Even for small commands, a complicated set of instructions needed to be coded.
Another engineer at AT&T had developed a B programming language which was a high-level language – real-world words could be used to write instructions for computers instead of the cryptic expressions used in assembly language. It also speeded up the process of writing programs because more tasks could be achieved by fewer lines of code.
There were some limitations in the B programming language and to overcome these limitations, Dennis Ritchie started working on another language that would be a step ahead of the existing B programming language. Since it was supposed to be a refinement of the B programming language, it was named as the C programming language.
Most of the UNIX operating system was written in the B programming language but back then it was in its nascent state. Ever since, most of the UNIX operating system has been rewritten in C.
Since then, the C programming language remains one of the most widely used programming languages in the world. Many other languages such as PHP and Java have derived their syntax from the original C language.
A brief history of C++
Initially, not many changes were made in the original C programming language. Bjarne quietly introduced object-oriented programming without making significant changes to the original programming syntax.
In 1990, the official “Annotated C++ Reference Manual” was released and then Borland’s Turbo C++ compiler was launched in the same year. Almost everyone who has learned C and C++ programming in the early and mid-90s remember installing the turbo C++ compiler on their 386 and 486 computers.
With everything turning GUI, within a few years Microsoft introduced Visual C and Visual C++ that allowed programmers to create Windows programs without having to do the groundwork for every program. For example, if you wanted to change the behavior of how a Windows button acted upon clicked, you could simply drag-and-drop the button object into the work area and then simply write the code inside the “Click” editor window.
With these basic intros of C and C++ out of the way, let’s now throw some light on the 10 most important differences between C and C++. Why should you choose one over the other for building your programs? In fact, if C++ has more features and capabilities compared to the C programming language, why should you even bother to read about the differences and simply opt for C++? This write-up is going to provide you some answers.
Main features and properties of the C programming language
• C is a procedural language.
• C follows a top-down approach in the sense that the main () function or module is processed the first and then the program proceeds towards the sub functions.
• It is a system programming language.
• It does not support classes and objects.
• It supports pointers.
Main features and properties of the C++ programming language
• C++ is object oriented and it supports classes.
• It is faster and more efficient.
• It follows a bottom-up approach – the sub functions are processed first and then the processing moves towards the main () function.
• It has a rich library of functions and routines that can be used to perform much advanced capabilities.
• C++ supports pointers and references.
Now we are quickly going to go through the individual differences between C and C++.
1. Type of programming
The most basic difference between C and C++ is that C is a procedural language and C++ is an object oriented language. In fact, this is a major change that happened during the transition. But what does that mean?
Most of the beginning programmers start learning programming through procedural programming. You arrange all the tasks that a machine needs to perform, step-by-step. Unless one procedure is completed, the program does not move to the other procedure unless one procedure is called (as a function) from another procedure.
Consequently, it follows a top-down approach. There is a main program that contains a list of all the procedures contained within it. Various functions are called by passing variables as parameters. Based on whatever processing takes place within the function, a value is returned.
C++ follows an object-oriented programming approach, which means objects or the classes that are created are more important and hence, they are built first to accomplish tasks. Consequently, it follows a bottom-up approach. When you call a function, it is a part of a class. By referencing to a class, you create an object (a class variable) and then all the functions and data types of the class become available through that object.
2. Application development
Since C is a procedural language it works on the lowest level of abstraction and consequently, it is good for systems programming. Initially when C was built, it was used both for low-level and high-level programming. The problem is, very complicated programs and applications are difficult to build in C, hence, C++ was born.
The C programming language is still used in embedded systems because it is light and easily compiled. It is nearer to the assembly language and hence, better suited for system programming. It does not have a very large set of libraries and hence, when it is compiled, the program that is created as a result is smaller.
Being one of the oldest languages, it is one of the most widely used languages all over the world. The C programming language is used for creating operating systems. UNIX was created using C. Even Microsoft Windows was initially created using C although right now it might be using all sorts of programming languages, including C++. The Android system is partially built with C and various Android applications are also built in C. The famous Mozilla Firefox browser has been developed with C but then again, C++ has been heavily incorporated now.
As mentioned above, the C programming language is also used for creating embedded systems. Embedded programs are small bits of programs that are installed in music systems, washing machines, TVs and these days, Internet of things appliances.
If you use Adobe Photoshop, you will be surprised to know that it has also been built using C.
What about C++?
Since C++ is an advanced extension of C, whatever application you can built in C, you can build them better and faster in C++. Consequently, all the software applications mentioned above have been enhanced using C++.
C++ is an object-oriented programming language. The Apple operating system and Linux have been built using C++. Postgres and MySQL have been written in C++. All major 3D games have been programmed in C++. The Maya 3D software has been developed using C++. It is the default choice for almost all banking applications due to its “black box” characteristics with the data that you supply to the classes is completely secure. The famous Infosys Finacle has been programmed using C++. Many Google applications are developed in C++.
Since C++ is at its strongest when creating classes, the language is also used for creating extensive libraries. Unlike C, C++ is compatible with other languages and hence, its libraries can be easily called from within other programs written in other languages.
3. The nature of syntax in C and C++
C is a structural or a procedural language. C++ is an object-oriented programming language. It supports polymorphism, abstract data types (even user-defined datatypes), encapsulation and inheritance (among many more). The basic structure of C++ is derived from C but since it is not a structural language, the flow of coding is quite different from C.
4. Data encapsulation
In C++ classes, data is completely safe. This is achieved with data encapsulation. This is why, classes are often termed as “black boxes” – what happens in the classes, remains in the classes. All its data values and functions are accessed through objects of the class type. The variables and datatypes defined within the class are only available within the class and they cannot be manipulated outside of the class.
Data encapsulation is not available in C. The variables can be private and global. These are easily available to the rest of the C program.
5. Data types in C and C++
This is one of the biggest differentiator between C and C++ – data types. Data types are the characteristics of the information that can be stored in variables. For example, if a variable is supposed to store an integer value, storing a string value or a character value in that variable generates an error. Conversely, if a string variable is made to store an integer value, this leads to an error.
They are important because this tells the operators what function to perform upon the variables when an operator is used. For example, does variable1+variable2 mean summation or concatenation (combining multiple strings)?
There are some common, standard data types available in both C and C++, for example
with C++ having some additional, but nonetheless, standard variables, including
• … and such
Then what’s the big difference?
The big difference is that in C++, you can have user-defined datatypes such as classes, structures and union.
A class in C++, containing all the necessary functions, data definitions and datatypes, is a datatype in itself. Such datatypes are not available in C.
6. C is function driven and C++ is object driven
The very essence of C++ is object-oriented programming. C on the other hand is a procedural programming language and hence, dependent upon functions. What’s the difference?
Object is a data type. Which means, when you are programming in C++, the main stress is on data, rather than the procedure or the function, which is the case in C.
Being a procedural language, when you are programming in C, your entire focus is on creating different functions. Yes, like classes, these functions are reusable and if you put many functions in a library, they are accessible through the library.
Being an object-oriented language, although you can access the functions contained within a class, what happens in the class, is not known to you and hence, there is a lesser chance of someone messing up the code and the data. This gives more security and encapsulation.
Inheritance is one of the core features in C++, but what does it mean?
It means creating more data types while inheriting some features of a pre-existing data type. Let’s take a small example.
There are three characters in a videogame: a man, a robot and a beer. Let’s assume that since it’s a videogame, all the characters can walk, talk, use arms, run, duck, jump and do all sorts of things.
Since they can all perform more or less the same functions, we can create a common character class that enables these characters to walk, talk, use arms, run, duck, jump and do all sorts of common things.
For every character we don’t have to define these capabilities separately because these are common capabilities. We can define these capabilities in a single class.
Once we have made sure that all these capabilities are being performed to perfection, our individual characters can inherit them, resulting in new data types.
For example, the man data type can inherit all the characteristics listed above from the main class. Additional features such as the character must look human and talk like a human can be added to a new data type.
A robot data type can inherit all the characteristics listed above from the main class. And so can the beer data type. Then afterwards, they can have their own individual characteristics.
This is called inheritance. Inheritance is available in C++, but not in C.
8. Function overloading and polymorphism
Function overloading, also called polymorphism in C++, means multiple functions can have the same name but different parameters. In plain language, “polymorphism” means the same entity having many forms.
What is a function?
A function of the segment of code that can be used to perform a specific task a single time or multiple times. For example, if you define a multiply (int a, int b) function, each time you have to multiply a set of numbers, you can invoke this function instead of repeatedly writing the same lines.
Normally a function has a predefined number of variables and a predefined set of data types in C. Suppose there is a function that is supposed to accept three parameters. If you supply four parameters to the function, it will give you an error and similarly, if you supply two parameters, again, it will give you an error.
Function overloading or polymorphism can take care of such exceptions in C++.
During function overloading, every new instance of the same function must have different number of variables/parameters and different types of data types.
Remember that type name is very important both in C and C++. The difference in C++ is that the data types are very tightly knitted around the classes and in the absence of a clear definition, the compiler may have to load multiple classes for multiple instances of the same class, needlessly. Polymorphism comes to rescue.
Another benefit of using function overloading is that you don’t have to create multiple names for the same function simply because it is using different data types.
A good example would be a function displaying information on the screen based on the set of parameters supplied.
Suppose there is a function called show_details ().
If parameters like student roll number, class number and the name of the student are supplied, the show_details () function shows information in the format that tells that the information about a student is being displayed.
But if a different set of parameters such as teacher ID, class ID, teacher name and salary category is supplied to the same show_details () function, it shows the information such that you can make out that the information belongs to a teacher.
9. Namespaces in C and C++
We first need to understand what namespaces are and what is their use.
The standard definition present on the websites like Microsoft says that “a namespace is a declarative region that provides a scope to the identifiers (the names of types, functions, variables,etc.) inside it.”
“Declarative region” means a region where the defined function or the variable acts within its scope. This way, there are no clashes if by mistake the same names are used.
You may not be able to feel the significance of namespaces when you’re writing a short program or even a small program for a department or a small retail store where an individual programmer or at the most a few programmers are working.
But what about something like the Google search engine or the Windows 10 operating system or Office 365? Millions of lines of codes are written by thousands of programmers defining hundreds of thousands of code libraries. Multiple programmers may end up using the same name for their functions and variables. But, C++ allows them to define namespaces and within those namespaces, it doesn’t matter what names are used, you’re not going to clash with the same names of other functions and variables. Namespaces are not available in C.
10. Error/exception handling in C and C++
Exceptions are runtime anomalies that a C or a C++ program encounters during its execution.
There are two types of errors to be handled when writing programs in C or C++ (and many other languages), namely
• Compile time errors
• Runtime errors
As the name suggests, compile time errors are encountered when the program is being compiled (the lines of code are being turned into various executable files so that the program can be run by the end user). Compile time errors can be like an incorrect reference to a library, a syntax error or an incorrect class import.
Runtime errors occur when, although the program has compiled perfectly, something the program needs to keep running is not happening and hence, such an error happens.
Why do you need exception or error handling routines? The simple answer is, what do you do if an error occurs in a program? Errors are bound to happen no matter how foolproof a program is.
For example, your program needs a text file to run. This text file must be there on your hard drive. What if the file is not there? How does a program know what to do if it doesn’t find the needed file? This is an “exceptional” situation for the program.
Another example: you have an online form on your website that customers must fill in. Every customer must enter an email ID to be able to submit the form. What happens if the customer does not enter an email ID? The program must know whether it should abort or show an error message to the customer so that if by mistake the customer has left out the email ID field, he or she may fill it.
In C language, all the known errors have an error code. Through multiple if-then-else decision loops, you can go through the individual error numbers or error codes and then based on the error code, you can take an alternative route or abort the program. This can be very long because when the program is being run in different environments, it can encounter hundreds, if not thousands of errors. A major chunk of your programming effort may go into handling various error codes.
C++ drastically reduces the effort required to handle exceptions/errors. It comes with an inbuilt library of exception handlers based on what sort of error is occurring. The moment an exception takes place, the control of the program is handed over to the exception handler and an appropriate action is taken by the C++ exception handling routine.
Going through the code examples of exception handling are beyond the scope of this write-up, but it suffices to say that there is a complete library of exception handling in C++, which is missing in C. Consequently, although it may be convenient to write a C++ program vis-à-vis error handling, the compilation ends up including bigger libraries, sometimes increasing the size of your program.
When writing C programs, you can choose which errors to handle if you can already anticipate all the errors that may take place when the program is run. This can significantly decrease the size of the end program.
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How do you decide whether you should choose C or C++ for your next project?
Both the languages have advanced a lot. In most of the case scenarios, it is better to use C++ than C because these days we have faster processors and more storage space. There may not be much difference regarding performance whether you work in C or C++.
C++ is more compatible with other programs. If your program needs to interact with some code written in another language, you will be better off working in C++ rather than C, which is, being a primitive language, less accepting of other languages.
On the other hand, there is a vast repository of C code. Practically every program has been written in C (though, it may have been rewritten in another language or script in its current form). C++ comes with its own libraries so theoretically, you should be able to complete a software application faster in C++, but since it has a greater number of libraries that are reusable, you can also create an application faster in C.
Compilation in C++ is more complicated compared to C. C is a procedural language and hence, better suited for writing assembly level programs for embedded systems. C++ is object-oriented and is more suited for working on end-user-related projects such as writing an accounting system or a graphic design system.
Both are highly capable languages but given the processing power and abundant computing resources we have these days, if you have an option of choosing, it is better to go with C++ because it gives you everything that C has, and more.
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