Computer Science 010

Lecture Notes 12

Customizing the Unix Environment,

Common Unix Programs,

and A Little About C++

Customizing Unix

.profile

.bashrc

Common Unix Programs

• xfig
• gnuplot
• xv
• gimp
• latex, dvips, gv

What is C++?

It's how you increment the value of C in C, of course.

We do not have enough time to cover C++ in any depth, but here are a few highlights of how it's different than C. C++ adds object-orientation to C but does so in a very different way than Java does. Many of the differences stem from the fact that C++ is backwards compatible with C. This means that you can take a C program and run it through a C++ compiler. It will compile and execute the same way. You cannot run a C program through a Java compiler, even though much of the syntax is similar.

This means that C++ suffers from all the drawbacks of C, although it adds tools which allow you to avoid some of the pitfalls if you use them properly. C++ does not check array lengths. It is still very easy to misuse pointers, causing your program to crash. You need to do your own memory deallocation.

C++ does add the following features to C:

• Classes - classes can be used to encapsulate data and functions. From an encapsulation perspective C++ classes are quite similar to Java classes. There are syntactic differences, however. For example, you should declare a class in a header file and place its body in a .cc file.
• C++ supports multiple inheritance. Java supports single inheritance via the extends clause. Multiple inheritance allows a class to inherit code from multiple classes. This is extremely complicated to do right.
• C++ adds exception handling similar to Java's.
• C++ has templates, a mechanism to define a class such as set and then instantiate the class so it only has elements of a single type. This cannot be done in Java currently although something like this is likely to appear in a future version of Java.

Bonus Topics

Anyone want to talk about... Unix System Administration?