Difference between C and C++

Difference Between C and C++

In this article, we are going to discuss the difference between C and C++ programming languages. C++ is often considered to be a superset of C, but this is not strictly true. Most of the C language code can easily be converted to compile correctly in C++, but there are a few differences that cause some valid C code to be invalid in C++ or to behave differently in C++. The common portability issue is that C++ defines many new keywords, such as new and class, that may be used as identifiers (e.g. variable names) in a C program. As the syntax of C and C++ has some similarities, but the basic approach in a C++ program is radically different from that in a C program. So there are a few major differences between C and C++.

S# C language C++ language
1. C is procedure-oriented language. C++ is an Object Oriented language.
2. C language is developed by Dennis Ritchie. C++ is an idea of Bjarne Stroustrup.
3. C is introduced in 1972. C++ is developed in 1979.
4. C emphasizes functions. C++ emphasizes more on data.
5. C is a middle-level language. C++ is a high-level language.
6. C is used to design medium size programs. C++ is used to design large programs.
7. Prototyping is not necessary for C language. Prototyping is Compulsory in C++.
8. A character constant in C is automatically converted into its equivalent ASCII. No such automatic conversion in C++.
9. In C main() function can be called within the program like the invocation of other functions. But in C++ it can be called with the help of classes.
10. In C, register variables cannot be addressed. In C++, it is possible.
11. Major input output functions are available in <stdio.h>. Major input output functions are available in <iostream.h>.
12. It does not support the concept of classes. It successfully implements the concepts of classes and objects.
13. It does not support the concept of polymorphism. It successfully implements the concept of polymorphism in the form of function and operator overloading.
14. C is a weekly typed language.  It is strongly typed language.
15. The C array model is pointer-based and one-dimensional without bound checking. Multi-dimensional, dynamic, and bound-checked arrays are implemented in C++.
16. C likes calls that pass primitive data or objects to functions. C++ is called that passes functions or messages to objects.
17. It can not model real-world applications. It is used for real-world modeling.
18. C is a superset of B. C++ is a superset of C.
19. Data is not secured. Data is secured (hidden).
20. C uses top-down approch. C++ uses bottom-up approach. 
21. C is function-driven. C++ is object driven.
22. C does not allow reference variables. C++ allows reference variables. 
23. It takes lesser memory for execution. It takes more memory for execution.
24. By using C, GUI Software can not be designed. By using C++, GUI-based software can be designed.
25. It is less compatible with higher versions of Windows. It is compatible with all versions of Windows.
26. It is an early 3rd generation language. It is a lateral 3rd generation language. 
27. It is not compatible with Java and C# programming language. It is compatible with Java and C# programming language.
28. It has a deep connection with Unix operating system. It has no connection with Unix and Unify operating systems.
29. It is powerful in graphics programming. It has weak properties in handling graphics programming.
30. Unix operating system was developed in C language. Some of the components of the Red hat Linux operating system were written in C++ programming language. 
31. Red hat Linux’s first multiuser GUI operating system has no connection with C language. Some of the components of the Red hat Linux operating system were written in C++ programming language.
32. Reverse keywords are small. Have large reserve keywords.
33. Have no virtual function property. Have virtual function property.
34. Enumeration is weekly used in C programming language. Enumeration is powerfully used in C++.
35. C++ programs cannot be compiled using a C compiler. C and C++ programs are compiled and executed in a C++ compiler environment. 
36. Overloading is not possible in the C programming language. Overloading is a powerful feature in the C++ programming language.
37. File handling is very easy in C programming language. File handling is complex in C++ for file organization and file management.
38. C language has no relationship with the Simula67 language. The C++ language has a deep relationship with the Simula67 language.

C++ was designed to be backward-compatible with C meaning that for the most part, C programs can compile unchanged with a C++ compiler. The below diagram depicts that C++ is a superset of C or in other words, C is a subset of C++. It also shows various features of each language.

Relationships of C and C++

Besides the above differences, the following are some major contrasts between C and C++:

  • C structures have a different behavior as compared to C++ structures. Structures in C do not accept functions as their parts.
  • C input/output is based on the library and the processes are carried out by including functions. C++ i/o is made through console commands cin and cout.
  • C does not support new or delete commands. The memory operations to free or allocate memory in C are carried out by free() and malloc().
  • Undeclared functions in C++ are not allowed. The function has to have a prototype defined before the main() before use in C++, although in C the functions can be declared at the point of use.
  • After declaring structures and enumerators in C the variables cannot be declared for the structure right after the end of the structure as in C++.
  • For an int main() in C++ a return statement may not be written but the return is mandatory in C if int main() is used.
  • In C++ identifiers are not allowed to contain two or more consecutive underscores in any position. C identifiers cannot start with two or more consecutive underscores but may contain them in other positions.
  • In C a character constant is automatically elevated to an integer whereas in C++ this is not the case.
  • In C declaring the global variable several times is allowed but this is not allowed in C++.


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