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C and C++

C vs C++: 30 Differences that Every Programmer Must Know

Posted in C, C++
C vs C++: 30 Differences that Every Programmer Must Know

C and C++ are two of the oldest surviving programming languages. The latter is directly derived from the former but flaunts more efficiency and productivity. Of course, both programming languages have their own advantages and drawbacks over one another.

C++ is an enhanced version of the C programming language with an additional feature of being object-oriented. C has been the motivation behind the birth of not only C++ but a multitude of presently popular high-level programming languages to the likes of Java, PHP, and Python.

Before going in-depth into the comparison between C and C++, let us first have a brief look at both the languages.

C – The Father of Modern Programming Languages

Making its first appearance in 1972, C was developed by Dennis Ritchie while working at Bells Labs. Though originally created for making utilities capable to run on the Unix platform, it is now one of the most widely used programming languages in the world.

C is a procedural programming language that works on the lowest level of abstraction and hence is a systems programming language. It is compiled, lightweight, and offers manual memory management.

The strength of C programming language lies in performance and has the ability to be used for coding for a wide variety of platforms. Hence, the programming language can be used for coding almost anything.

Though nowadays we have specialized as well as a wide variety of programming languages to pick from, C was a great invention during its infancy and early years. Its level of versatility was unmatchable during its younger years.

C++ – The Best Prodigy of C

Designed by Bjarne Stroustrup, C++ first made its appearance in 1985. Bjarne started working on the programming language while working at Bell Labs in 1979. He wanted to develop an extension to the C programming language that is both more efficient and flexible than the C.

C++ provides support for object-oriented programming. It offers a low level of abstraction and requires manual memory management. The programming language is comparable to C, lightweight, and compiled. It is capable of developing apps for a diverse range of platforms.

The C++ programming language has almost everything that C has to offer but in a better way. Like its original inspiration, the C programming language, C++ has and continues to, influence a range of high-level programming languages, such as C# and Java.

C vs C++: Head to Head Comparison

In order to make the most out of all the dissimilarities mentioned below, you need to have at least an intermediate skill level in C and C++. If not, then here are some best C and C++ books to build it.

Application Development Area

C is a good option for embedded devices and system-level code. C++, on the contrary, is a top choice for developing gaming, networking, and server-side applications. It is also a great option for the development of device drivers.

The authority of C++ lies in performance and speed. Though C also offers these both qualities, C++ takes it a step further.

Know more about applications, features, and uses of C++.

Approach

Being a procedure-oriented (structure-oriented) programming language, C follows a top-down approach. It begins with the high-level design and ends with the low-level design.

In the top-down approach, the main() function is written at first and all subfunctions are called from the main() function. Thereafter, sub-functions are written as per the requirements.

The C++ programming language is completely opposite to C in this aspect as, like all object-oriented programming languages, it follows a bottom-up approach.

Opposed to the top-down approach, the bottom-up approach starts with the low-level design and finishes with the high-level design. In the bottom-up approach, the code is developed for modules and afterward, these modules are integrated with the main() function.

Both types of approaches are involved in software development and not in program execution. In the present times, software design includes the combination of both approaches to get the best of both worlds.

Compatibility With Each Other

C is a subset of C++. Hence, C++ is a superset of C. While C++ is able to run most C code, the C compiler isn’t able to execute the C++ code.

Compatibility With Other Programming Languages

The C++ programming language provides compatibility with other generic programming languages. However, no such feature is offered by the C programming language.

Data Security, Encapsulation, and Information Hiding

As data and functions are treated as distinct entities in the C programming language, there is no support for encapsulation. The C++ code binds data and functions together in an object and, hence, supports encapsulation, which, in turn, offers information hiding.

Another major distinction between C and C++ programming languages is on the basis of data security. In the C programming language, data not as secure.

Variables

By virtue of being an object-oriented programming language, C++ is capable of hiding variables in a class while offering only a function interface. Modifiers can be used for class members in order to make the data inaccessible for external users.
No such concept exists in the C programming language. As a consequence, all variables are open and therefore, vulnerable to be accessed by some malicious code.

Enumerations

Declaring enumerations is possible in C. However, the declared enumeration constants are of integer type. In that sense, an enumeration declaration is similar to declaring a number of integer constants. Plus, there is no additional type safety.
In C++ programming language, an enumeration is a distinct type. This means that it’s impossible to assign a value of integer type to a variable of an enumeration type unless an explicit conversion is used.
Nonetheless, it is possible to assign a value of an enumeration type to some variable of the integer type. This is because enumeration types allow implicit conversion by means of integral promotion. A static checker can easily detect this implicit conversion and provide a warning if needed.

Use of Strings

Another important distinction between the security measures offered by C and C++ lies in the use of strings.
The char[] represents string literals in C. When passed to some external function, there is a good possibility of the function modifying the original string. To make things even worse, there is no way to prevent such a happening.
On the contrary, C++ has a variable type called string. As this variable type is immutable, it can’t be changed at the original location.

Data Types

C supports inbuilt and primitive data types. On the contrary, C++ provides support for user-defined data types in addition to primitive and built-in data types. Moreover, C++ has Boolean and String as built-in data types. No such inbuilt data types exist in the C programming language.

Default Header File

Yet another distinction that can be made between C and C++ is on the basis of the default header file used. While C uses stdio.h as the default header file, C++ makes use of the iostream.h as the default header file.

Ease of Coding

C is described as a hands-on programming language. Hence, it is essential to tell the program everything that needs to be done. As an extension of C, C++ allows for highly controlled object-oriented code. Simply, if C is easy then C++ is easier.

Exception Handling a.k.a. Error Handling

C++ offers an easy way of exception handling by means of Try and Catch blocks. Exceptions are meant for spotting “hard” errors, which can result in incorrect code.

Unlike C++, exception handling in C needs to be managed by using other functions. This is because the programming language doesn’t provide support for exception handling.

Conventionally, a programmer coding in C needs to prevent errors from occurring beforehand. Hence, it is required to test return values from functions. In the worst case where the error is inevitable, the programmer must log the error and terminate the program gracefully.

File Extension

Any C program is saved with a .c extension while a typical C++ program is saved with a .cpp extension

Function Overloading

One of the powerful features brought to the table by C++ programming language is function overloading, a form of polymorphism. It enables a function with the same name to be defined for varying purposes. Overloaded functions have the same name albeit different parameters.

For instance, a function add() can be defined in two ways. While one is able to calculate the sum of integer values, the other version can concatenate two (or more) strings. Unlike C++, the C programming language doesn’t provide support for function overloading.

Functions with Default Arguments

While C++ allows using a function with default arguments, C doesn’t. If such a function is called by passing argument(s) then those argument(s) are used by the function.

GUI Programming

For enabling GUI (Graphical User Interface) programming, C has the GTK tool. C++ supports Qt tools for achieving the same.

Inheritance

Inheritance is the ability of a class to derive properties as well as characteristics from some other class. As it is one of the important properties of OOPS, no such feature is available in the C programming language.

The class that inherits properties from another class is called the child class. It might also be known as derived or subclass. The class whose properties are inherited by the subclass is known as the base class. It is also referred to as the parent or superclass.

Inline Functions

C makes use of the Macro function as a means for optimization technique, especially for reducing the overall execution time. C++, on the other hand, uses inline functions for optimizing the written code.

Functions that are instructed as inline functions to the compiler allows it to replace their function definition wherever they are being called. The C++ compiler replaces the definition of the inline functions at compile time instead of referring their function definition at runtime.

One important thing to note about inlining in C++ is that it is a kind of suggestion made to the compiler. If the function is too big then the compiler can ignore the inline request and execute them as normal functions.

Input and Output Operations

The C programming language uses scanf() and printf() for input and output, in the respective order, operations. On the contrary, C++ has cin for performing input operations and cout for performing output-related operations.

Keyword Count

C++ has a total of 52 reserved keywords whereas C has only a total of 32 keywords.

Mapping

The C programming language has a very complicated mapping between data and function. In C++, the mapping between data and function can be easily established by means of classes and objects.

Memory Management

Although both C and C++ require manual memory management, the way it is achieved is different. C offers calloc() and malloc() functions for dynamic memory allocation and the free() function for memory deallocation.

In C++, the new operator is used for dynamic memory allocation while the delete operator is there for accomplishing memory deallocation.

Namespace

Namespaces grant the ability to group named entities into a narrower scope, called the namespace scope. Without namespaces, these named entities would have a global scope. In other words, a namespace is a declarative region providing a scope to the identifiers inside it.

The simple reason for using namespaces is to organize the elements of the program into distinct logical scopes referred to by names. While C++ supports the feature, the feature is unavailable from the C programming language.

C++ allows several namespace blocks to share the same name. All declarations made within such blocks are declared in the named scope. Any namespace definition starts with the namespace keyword followed by the name of the namespace. The general syntax is:

namespace some_name

{ // code goes here }

Some important points to remember about using namespaces in C++ are:

  • A namespace declaration can’t have access specifiers
  • It is possible to nest namespace declarations within another namespace declaration
  • Namespace declarations can be made only at the global scope
  • The definition of a namespace can be fragmented into several units
  • There is no need of adding a semicolon (;) after the closing brace of the definition of the namespace

Operator Overloading

While operator overloading isn’t possible in the C programming language, C++ supports the notion. Simply, it is a feature that allows changing the way an operator works for user-defined types.

For the basic types i.e. int, double, float, the meaning of an operator always stays the same. For user-defined types, however, it is possible to redefine the way an operator will work.

A special operator function needs to be defined inside a class for overloading an operator. Operator overloading is widely used by programmers to make the program more intuitive.

Polymorphism

One of the essential features of object-oriented programming is a polymorphism. Hence, C++ supports it. Polymorphism in C++ simply means that a call to a member function will result in the execution of a distinct function based on the type of the object that invokes the function.

In C++, polymorphism typically occurs when there is a hierarchy of classes and the same are related by means of inheritance.

There is no built-in support for polymorphism in C like C++. However, there are some design patterns, such as function pointers, that can offer a logical equivalent of dynamic dispatch.

Program Subdivision

Any C++ program can be divided into classes and objects. A C program, on the other hand, is divisible into modules and procedures.

Programming Style

The C programming language follows a procedural style programming, which simply means that it doesn’t support the concept of classes and objects. C++, on the other hand, is a programming language that supports the notion of multi-paradigm.

Being a multi-paradigm programming language enables C++ to provide support for both procedural and object-oriented styles of programming. Despite being truly object-oriented, supporting procedural programming makes C++ much like a hybrid programming language.

Being object-oriented means that C++ enhances productivity as well as the organization of the code. Both qualities are essential when developing complex applications. The object-oriented nature of C++ makes is a top-choice for developing server-side software and fast applications.

C puts an emphasis on the steps or procedures followed for solving a particular problem. C++, on the other hand, primarily stresses upon objects. This is because it has a higher level of abstraction than the C programming language.

Reference Variables

While C++ provides support for reference variables, C doesn’t. A reference variable is another name for an existing variable. After a reference is initialized for a variable, both the variable name and variable reference can be used for referring to the variable.

P.S. - Both programming languages, however, provide support for pointers.

Scope

C is a general-purpose programming language with more emphasis on system programming. Hence, it is excellent for embedded systems. On the other hand, C++ is a pure general-purpose programming language, making it a top-choice for various walks of application development.

The main() Function

C allows calling the main() function through other functions used in the code. In C++, it is not possible to call the main() function through other functions.

Use of Functions inside Structures

C++ supports using functions in structures. A structure is much similar to a class in several aspects. However, the main distinction lies between the two in terms of the default access level.

Every functionality that is supported by a class is also supported by a struct. Methods are used in the same way for a structure as they are used for a class. However, it is not possible to define a function within a structure in the C programming language.

Check out differences between structures and union in C.

Variables

It is mandatory to declare variables at the beginning of the function in a C program. However, variables can be declared anywhere in the function in the C++ programming language.

The C programming language allows multiple declarations to be made of global variables. This is not the case with C++, which doesn’t allow multiple declarations of global variables.

Virtual and Friend Functions

Any function that is a member function and declared within a base class is overridden by a derived class is called a virtual function. The main purpose of virtual functions is to achieve runtime polymorphism. For making any function virtual, the virtual keyword is used.

A friend function belonging to a class is one that is defined outside its scope but has the privilege to access all private and protected members of the class. Though prototypes of friend functions appear in the class definition, they are not member functions.

In addition to a function, a friend function can be a function template, member function, class, or class template. In order to make a function a friend function, the function prototype in the class definition is preceded with the keyword friend.

C doesn’t have either friend or virtual functions, while C++ has both.

C vs C++: When and Which to Pick?

You need to pick C over C++ when,

  • Coding truly tiny systems (results in a little less overhead as compared to using C++)
  • The application needs to be incredibly stable (Impermeable code and control results by removing the abstractions of C++)
  • You don’t have a C++ compiler on the platform of choice for application development

You need to choose C++ over C when,

  • Developing an application that works directly with the computer hardware
  • Developing an application that deals with application development
  • The project aims for extremely low-level processing

Final Words!

That wraps up the differences between C and C++ programming languages. Both of them are among the leading options for making a great living from programming. Hence, it is a great time to brush-up your C and C++ skills or start developing them, if you haven’t already.

Are there any differences between C and C++ that we missed? Or is there something factually incorrect in the article? Share your views via the dedicated comment window below.

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Vijay Singh

Vijay Singh

My name is Vijay Singh Khatri, and I enjoy meeting new people and finding ways to help them have an uplifting experience. I have had a variety of customer service opportunities, through which I was able to have fewer returned products and increased repeat customers, when compared with co-workers. Currently working with hackr.io View all posts by the Author

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RJD
RJD

Bad Article, a lot of typos, very misleading phrases, wrong Information provided to us by a customer service agent. Article should be flagged as personal opinion and not as an actual fact related article. This is something that belongs on a private Blog. And even then... how can this still be on here?

Wilfrantz Dede
Wilfrantz Dede 10 Points

Great article!

matt
matt

WTF

Hardy
Hardy

Great article. Too bad its more opinion than fact.

The article states that
1. C++ strings are immutable. I don't think so. (Java strings are immutable.)
2. C++ strings are builtin types. I don't think so.
3. C++ and object oriented are bottom up. I don't think so. For example, one might define a type and then if and when the need arises, define sub-types. C++ can be used in whatever way one wishes.
4. C is top down. I don't think its either top down or bottom up. It can be used in whatever way one wishes.

Dan O'Hara
Dan O'Hara

You mention:
>> While C++ is able to run most C code, the C compiler isn’t able to execute the C++ code.

I found this a little awkward. C++ doesn't run code, it compiles source text to an intermediate file which usually has to be linked to become executable. What you likely intended to say is that the C compiler can't compile C++ source text, but the C++ compiler can compile C source text.

Wilfrantz Dede
Wilfrantz Dede 10 Points

I agree.