CS201 Midterm Highlighted Handouts by VU Topper RM

Summary

o What is programming o Why programming is important o What skills are needed o Develop a basic recipe for writing programs o Points to remember

What is programming

As this course is titled “Introduction to programming”, therefore it is most essential and appropriate to understand what programming really means. Let us first see a widely known definition of programming.

Definition: "A program is a precise sequence of steps to solve a particular problem.”

It means that when we say that we have a program, it actually means that we know about a complete set activities to be performed in a particular order. The purpose of these activities is to solve a given problem.

Alan Perlis, a professor at Yale University, says:

" It goes against the grain of modern education to teach children to program. What fun is there in making plans, acquiring discipline in organizing thoughts, devoting attention to detail and learning to be self-critical? "

It is a sarcastic statement about modern education, and it means that the modern education is not developing critical skills like planning, organizing and paying attention to detail. Practically, in our day to day lives we are constantly planning, organizing and paying attention to fine details (if we want our plans to succeed). And it is also fun to do these activities. For example, for a picnic trip we plan where to go, what to wear, what to take for lunch, organize travel details and have a good time while doing so.

When we talk about computer programming then as Mr. Steve Summit puts it

“At its most basic level, programming a computer simply means telling it what to do, and this vapid-sounding definition is not even a joke. There are no other truly fundamental aspects of computer programming; everything else we talk about will simply be the details of a particular, usually artificial, mechanism for telling a computer what to do. Sometimes these mechanisms are chosen because they have been found to be convenient for programmers (people) to use; other times they have been chosen because they're easy for the computer to understand. The first hard thing about programming is to learn, become comfortable with, and accept these artificial mechanisms, whether they make ``sense'' to you or not. “

Why Programming is important

The question most of the people ask is why should we learn to program when there are so many application software and code generators available to do the task for us. Well the answer is as give by the Matthias Felleisen in the book ‘How to design programs’

“The answer consists of two parts. First, it is indeed true that traditional forms of programming are useful for just a few people. But, programming as we the authors understand it is useful for everyone: the administrative secretary who uses spreadsheets as well as the high-tech programmer. In other words, we have a broader notion of programming in mind than the traditional one. We explain our notion in a moment. Second, we teach our idea of programming with a technology that is based on the principle of minimal intrusion. Hence, our notion of programming teaches problem-analysis and problem-solving skills without imposing the overhead of traditional programming notations and tools.”

Hence learning to program is important because it develops analytical and problem solving abilities. It is a creative activity and provides us a mean to express abstract ideas. Thus programming is fun and is much more than a vocational skill. By designing programs, we learn many skills that are important for all professions. These skills can be summarized as: o Critical reading o Analytical thinking o Creative synthesis

What skills are needed

Programming is an important activity as people life and living depends on the programs one make. Hence while programming one should

o Paying attention to detail o o Think about user interface o Understand the fact the computers are stupid o

Paying attention to detail

In programming, the details matter. This is a very important skill. A good programmer always analyzes the problem statement very carefully and in detail. You should pay attention to all the aspects of the problem. You can't be vague. You can't describe your program 3/4th of the way, then say, " You know what I mean?'', and have the compiler figure out the rest.

Furthermore you should pay attention to the calculations involved in the program, its flow, and most importantly, the logic of the program. Sometimes, a grammatically correct sentence does not make any sense. For example, here is a verse from poem " Through the Looking Glass" written by Lewis Carol: “Twas brillig, and the slithy toves Did gyre and gimble in the wabe “

The grammar is correct but there is no meaning. Similarly, the sentence, " Mr. ABC sleeps thirty hours every day", is grammatically correct but it is illogical.

So it may happen that a program is grammatically correct. It compiles and runs but produces incorrect or absurd results and does not solve the problem. It is very important to pay attention to the logic of the program.

When ever you are writing a program, always keep in mind that it could be reused at some other time. Also, try to write in a way that it can be used to solve some other related problem. A classic example of this is:

Suppose we have to calculate the area of a given circle. We know the area of a circle is (Pi * r2). Now we have written a program which calculates the area of a circle with given radius. At some later time we are given a problem to find out the area of a ring. The area of the ring can be calculated by subtracting the area of outer circle from the area of the inner circle. Hence we can use the program that calculates the area of a circle to calculate the area of the ring.

Think about Good user interface

As programmers, we assume that computer users know a lot of things, this is a big mistake. So never assume that the user of your program is computer literate. Always provide an easy to understand and easy to use interface that is self explanatory.