C++ vs. Java: Similiarities & Differences

C++ vs. Java: Similiarities & Differences Dr. Jeyakesavan VeerasamyDirector of CS UTDesign program & CS Teaching Faculty jeyv@utdallas.eduUniversity of Texas at Dallas, USA

History • C (1969)  C++ (1979)  Java (1995) • Both support OOP. Most OOP library contents are similar, however Java continues to grow. • Syntax is very close – Java has strong influence of C/C++. Easy to learn the other language when you know one of these.

C++ compiler & Linker usage file1.cpp file2.cpp filen.cpp …. Compiler Compiler Compiler file1.o file2.o filen.o …. Linker This appliction runs directly on top of OS. C++ compiler does not care about filenames. application (executable)

Java compiler usage file1.java file2.java filen.java …. Compiler Compiler Compiler file1.class file2.class filen.class …. Java Runtime Environment (JRE) Operating System

C++ vs. Java: differences

C++ vs. Java: differences …

Types of memory used by executable task data (static) heap (dynamic) Code Stack

Objects • Objects can be created as local variables just like any basic data types in C++. C++: ComplexType num1; Java: Nothing equivalent – Objects cannot be in stack.

Objects in Heap C++: ComplexType *num1 = new ComplexType(…); Java: ComplexType num1 = new ComplexType(…);

Arrays • Basic data types and classes are treated the same way in C++, unlike Java. C++: ComplexNumber numbers[5]; Java: nothing equivalent.

C++ array version #2 ComplexNumber *numbers; numbers = new ComplexNumber[5]; Java: nothing equivalent for classes, but possible for basic data types: int numbers[]; numbers = new int[5];

C++ array version #3 ComplexNumber **numbers; numbers = new ComplexNumber*[5]; for( index i = 0 ; i < 5 ; i++) numbers[i] = new ComplexNumber(…); Java: ComplexNumber numbers[]; numbers = new ComplexNumber [5]; for( index i = 0 ; i < 5 ; i++) numbers[i] = new ComplexNumber(…);

C++ vs. Java: Analogy • Working with C++ is like flying a airpline, while working with Java is like driving a car. • What does it mean? • Too many controls/options in C++: think before use each one. • Careful use can result in efficiency, poor use can result in serious inefficiency • Issues like memory leak can crash the application, out-of-bounds array access can cause memory corruption – but it may not show up for long time – causing lot of headache! • Java : slow and steady wins the race?

References • C++ tutorials: http://www.cplusplus.com/files/tutorial.pdf, http://www.learncpp.com/ • C++ reference: http://en.cppreference.com/w/ • Java tutorial: http://docs.oracle.com/javase/tutorial/ • Java API documentation: http://docs.oracle.com/javase/6/docs/api/

C++ vs. Java: Similiarities & Differences