1 The Catholic University of Eastern Africa P.o Box , Nairobi Kenya Edward Kioko 2013

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Purpose of the module (A constituent College of Kenyatta University) P.O Box 136-90100, Machakos Kenya Telephone: 044-21604 Email: info@machakosuniversity.ac.ke Website: http://www.machakosuniversity.ac.ke SCO102: introduction to programming Prepared by: Edward M Kioko Email:-kioko@cuea.

1 Purpose of the module (A constituent College of Kenyatta University) P.O Box , Machakos Kenya Telephone: Website: SCO102: introduction to programming Prepared by: Edward M Kioko -kioko@cuea.edu Tel:+254 (0) August, 2014 In this 3 month instructor-led course, student shall learn the fundamental skills for programming languages. Learners will use a high level language (C programming language) to solve scientific problem. The module provides a basic an entry point for students in the field of software engineering. Learning Outcomes By the end of the module, students will be able to: Understand the basic principles in programming Understand problem solving strategies Understand the process of creation of a computer program and the different approach Use high level language to code, write, compile, link and execute a program with emphasis on scientific applications 1 The Catholic University of Eastern Africa P.o Box , Nairobi Kenya Edward Kioko 2013

2 Course outline Programme Module Name Module Code : SCO 102 Credit Hours week Semester : BSc Computer science : introduction to programming : 2hours per week; Lab work 3 hours per Semester : August-Dec 2014/2015 Course Leader : Edward Kioko Meeting hours : Friday 8:00-1:00 Venue Website Program : Electrical Lab : kioko@cuea.edu : : Regular Module Schedule (August December 2014/2015) Wee k Topic/Content 1 & 2 Student registration & introduction to the module Introduction to programming methodology Programming language levels Factors to consider while selecting a Com ment 2 The Catholic University of Eastern Africa P.o Box , Nairobi Kenya Edward Kioko 2013 programming language Translators Overview of C language Development environment and cycle Syntax of a C program 3 Program design and logic 4 & 5 6 & 7 Algorithm Flowcharts & Pseudo code Basic Elements of programming Identifiers and keywords Commenting in data types Operators Constants and variables Control structures Decision control structure loop Continuous Assessment Test 8 & 9 Modular programming in C( functions)

3 10 & 11 Arrays in C Lab Practical Assignments 10% Lab 20% Exam: 60%. 100% END OF SEMESTER EXAMINATIONS Teaching Methodologies: Lectures, demonstrations, group/class discussions and practical exercises Instructional Materials/Equipment: Computers, projectors, whiteboards and writing materials. Recommended References: 1. Kerinignan, B. W., & Ritchie, D. M. (2010). The C programming Language (second Edition ed.). New jersey: Prentice Hall P T R. 2. King, K. C Programming: A Modern Approach. Course Assessment: I CAT: 10% 3 The Catholic University of Eastern Africa P.o Box , Nairobi Kenya Edward Kioko 2013

4 Contents Chapter One: Introduction to programming Chapter objectives Introduction to programming Programming levels Factors to consider while selecting a programming language Translators The development environment and the development cycle Overview of C language C program structure and syntax Chapter summary Chapter exercise Further reading suggestion Chapter Two: Program Design Process and Logic Chapter objectives Introduction Program development Lifecycle (PDLC) Programming design and logic tools Algorithms The Catholic University of Eastern Africa P.o Box , Nairobi Kenya Edward Kioko Flow charts Pseudocode Control Structures/Logical Structures Chapter summary Chapter exercise Chapter objectives Introduction Key words Comments in C Chapter three: Fundamentals of C programming Data types in C Variables Numeric variables Character variables Assignment Constants in c programming Arithmetic operators Escape sequence Statements Casting Data Types Input and output... 33

5 3.13 Formatted input scanf Character I/O getchar& putchar Chapter Four: Control structures in C Introduction Chapter objectives Boolean expressions and relational operators Compound Boolean expressions using logical operators Control structures in C Decision control structures Switch statement in C Repetitive control structures in C Chapter summary Chapter exercise Further reading suggestions Chapter Five: Functions in C Introduction Chapter objectives Benefits associated with Functions Defining a function in C Function declaration Function calls Parameters and arguments Recursive functions in C Number Factorial Fibonacci Series Variable scope Local Variables Global Variables Formal Parameters Chapter summary Chapter exercises Further reading suggestions The Catholic University of Eastern Africa P.o Box , Nairobi Kenya Edward Kioko 2013

6 Chapter One: Introduction to programming 1.1 Chapter objectives By the end of this, learners should be able to: Understand programming levels Learn fundamental concepts underlying programming languages Understand the Program Development Life Cycle (PDLC) Understand the factors to consider while selecting a programming language Indentify the different parts of a C program Able to write, debug and execute a simple C program 1.2 Introduction to programming Users communicate with the computer in a language understood by it. It needs to be instructed to perform all the tasks. The instructions are provided in the form of computer programs, which are developed by a programmer using a programming language. The language, which the user employs to interact with the computer is known as computer programming language. The process of using such languages to instruct the computer is known as programming or coding. We can therefore define a programming language as computer language used by programmers to develop applications, scripts, or other set of instructions for a computer to execute. It is a series of instructions that instruct the computer on how to perform tasks 1.3 Programming levels The figure below is intended to illustrate several key points about programming languages. First, programming languages are built upon and relate directly to the underlying computer (hardware). In fact, they are designed to control the operation of the hardware. Second, these programming languages can be divided into TWO major groups; low and high level programming languages Low-level Languages are machine-dependent i.e. must run on specific machines. They require extensive knowledge of computer hardware and its configuration. They are further divided in to Machine language and Assembly language High-Level Languages are machine-independent hence can ran on different types of machines 6

Figure 1: Levels of Programming Languages Programming Language Low Level High level Machine Language Assembly Language Procedural Object oriented Machine Language It s the only language that is

It is considered to be first generation language.

7 Figure 1: Levels of Programming Languages Programming Language Low Level High level Machine Language Assembly Language Procedural Object oriented Machine Language It s the only language that is directly understood by the computer therefore it does not need any translation. Its written as strings of 1 s (one) and 0 s (zero. Program instruction may look like this: It is considered to be first generation language. Advantage of Machine Language The only advantage is that program of machine language run very fast because no translation program is required for the CPU. Disadvantages of Machine Language It is very difficult to program in machine language. The programmer has to know details of hardware to write program. The programmer has to remember a lot of codes to write a program which might easily result in program errors. It is difficult to debug the program. Assembly Language Instead of using a string of binary bits in a machine language, assembly language use English-like words as commands that can be easily interpreted by programmers. These commands are referred to as mnemonics. Examples of mnemonics in assembly language include ADD, SUB, MUL, DIV. 7

8 Assembly language source must be translated into machine code by a separate program known as assembler. The machine code can run on its own at any time therefore the assembler and the source code are no longer needed. If you make any changes to the source code, the assembler shall be needed to recompile the program again and generate a new object program. Advantages of Assembly Language Mnemonics are easier to understand hence saving the programmer lot of time and effort. It is easier to correct errors and modify program instructions. Assembly Language has the same efficiency of execution as the machine level language. Because this is one-to-one translator between assembly language program and its corresponding machine language program. Disadvantages of Assembly Language: Its machine dependent hence a program written for one computer might not run in other computers with different hardware configuration i.e. there is no program portability. It is necessary to remember the registers of CPU and mnemonic instructions by the programmer. Several mnemonic instructions are needed to write in assembly language than a single line in high-level language. Thus, assembly language programs are longer than the high language programs Advantages of Low-level Languages Low-level languages have the advantage that they can be written to take advantage of any peculiarities in the architecture of the central CPU. Thus, a program written in a low-level language can be extremely efficient, making optimum use of both computer memory and processing time Disadvantages of Low-level Languages To write a low-level program takes a substantial amount of time, as well as a clear understanding of the inner workings of the processor itself. Therefore, low-level programming is typically used only for very small programs, or for segments of code that are highly critical and must run as efficiently as possible High-Level Languages High-level programming languages allow the specification of a problem solution in terms closer to those used by human beings. These languages were designed to make programming far easier, 8

9 less error-prone and to remove the programmer from having to know the details of the internal structure of a particular computer. These high-level languages were much closer to human language. Examples include Java, Python, Prolog e.t.c. They are very convenient but very far removed from the computer they are running on. They are independent hence can run on different types of machines Programming paradigms Procedural programming Programming instructions to tell the computer what to accomplish and how to accomplish it. Some common procedural programming languages include BASIC, COBOL, C among others e.t.c Object Oriented Approach Structured programming doesn t explain how to keep data and programs together. However with OOP approach, data and programs (methods) are packaged into a single unit called an object. OOP are event driven. Example of OOP languages include C ++, java and java applets Advantages of High-level Languages High-level languages permit faster development of large programs. The final program as executed by the computer is not as efficient, but the savings in programmer time generally far outweigh the inefficiencies of the finished product. This is because the cost of writing a program is nearly constant for each line of code, regardless of the language. Thus, a high-level language where each line of code translates to 10 machine instructions costs only one tenth as much in program development as a low-level language where each line of code represents only a single machine instruction. 1.4 Web page program development tools They are tools used to create web pages. Example of these tools includes: HTML (Hypertext MarkUp Language) - it s not actually a programming language but contains special codes used to create and format web pages. It usually uses tags that should be kept as an ASCII file Dynamic HTML(DHTML)-allows users to add more graphics and interactivity on the web page e.g. perform animations. Extensible MarkUp language (XML) allows web page developers to create tags that describe data pass to client so that the client can process the data rather than the server. 9

10 XHTML( extensible HTML) includes features of HTML and XML WML (Wireless Markup Language) allows web page developers to design pages specifically for micro browsers. It uses the Wireless Application Protocol (WAP) Web page authoring which include Dreamweaver, FrontPage, Joomla flash e.t.c. 1.5 Factors to consider while selecting a programming language The features of one programming language may differ from the other. One can be easy and simple, while others can be difficult and complex. A program written for a specific task may have few lines in one language, while many lines in the other. We judge the success and strength of a programming language with respect to standard features. There a number of factors while selecting a programming just to mention a few Ease of Use It s the most important factor in choosing a language. The language should be easy in writing codes for the programs and executing them. The ease and clarity of a language depends upon its syntax. It should be capable enough to provide clear, simple and unified set of concepts. The vocabulary of the language should resemble English (or some other natural language). Symbols, abbreviations and jargons should be avoided unless they are already known to most people. Any concept that cannot be easily explained to amateurs should not be included in the language. Good Programming Language Features Its definition should be independent of any particular hardware or operating system. It should support software engineering technology, discourage or prohibit poor practices, and promote or support maintenance activities. It should support the required level of system reliability and safety. If the language does not support the basic requirements, then it is advisable to learn a new language and then start the application development. Nature of Application Each language provides certain distinctive features, which separates it from other languages. For example, Java should be used to write an application that runs over the Internet, whereas to develop a system application, C and C++ are used. 10

11 Language Acquaintance In cases where a number of languages may suit the application to be developed, the most familiar language to the programmers should be chosen. Ease of Learning Sometimes, it may necessity the programmer has to learn a new language in order develop an application. In such a case, the first step is to find out which language, along with its alternatives, would be suitable for the proposed application. Then, the programmer has to decide which language is easier to learn and use. Control over Resources Apart from the ease of use, the control factor should also be considered while selecting a language. Easy to learn and use feature of the language does not mean that the application created with it will be the most powerful. Certain applications require more control over the hardware and hence the control factor should not be ignored. If the application developed by an easy language is not efficient enough, then it is better to slug it out with a more complex language. For example, Visual Basic provides an easier way to develop an application, but it does not have the same control over the resources as other languages such as Visual C++ or Delphi Speed Requirement Some applications e.g. railway or air reservation need to be quick as compared to batch processing applications such as payroll and inventory control. In such cases, the execution efficiency is important and the programmer should use assembly language instead of high-level languages. The main reason behind this is that assembly language usually has a shorter production time as compared to high-level languages. 1.6 Translators It s a program that converts source statement into machine language. The source statements are just like English words. The computer interprets the instructions as 1's and 0's. A program can be written in assembly language as well as in high-level language. This written program is called the source program. The source program is to be converted to the machine language, which is called an object program Translators can be classified as depicted below follows 11

12 Translators are as follows: a) Assembler b) Compiler c) Interpreter Assembler They are programs that convert assembly code to equivalent machine code. It will translate the symbolic codes of programs of an assembly language into machine language instructions. The symbolic language is translated to the machine code in the ratio of one is to one symbolic instructions to one machine code instructions Compiler It is a program which translates a high level language program into a machine language program. A compiler is more intelligent than an assembler. It checks all kinds of limits, ranges, errors etc. But its program run time is more and occupies a larger part of the memory. It s relatively slow in speed since it goes through the entire program and then translates the entire program into machine codes. If a compiler runs on a computer and produces the machine codes for the same computer then it is known as a self compiler or resident compiler. On the other hand, if a compiler runs on a computer and produces the machine codes for other computer then it is known as a cross compiler. Compilers will show errors and warnings for the statements violating the syntax rules of the language. They also have the ability of linking subroutines of the program Interpreter It translates high level languages into machine code. It translates only one statement of the program at a time. It reads only one statement of program, translates it and executes it. Then it reads the next statement of the program again translates it and executes it. In this way it proceeds further till all the statements are translated and executed. On the other hand, a compiler goes through the entire program and then translates the entire program into machine codes. A compiler is 5 to 25 times faster than an interpreter. 12

13 By the compiler, the machine codes are saved permanently for future reference. On the other hand, the machine codes produced by interpreter are not saved. An interpreter is a small program as compared to compiler. It occupies less memory space, so it can be used in a smaller system which has limited memory space. 1.7 The development environment and the development cycle Programs goes through 3 main phases during development: editing (writing the program), compiling (i.e., translating the program to executable code and detecting syntax errors) and running the program and checking for logical errors (called debugging). 1. Editing This involves typing in the program with a text editor and making corrections if necessary. The program is stored as a text file on the disk 2. Compile The translator converts the source into machine language code (object code), which it stores on the disk.a linker then links the object code with standard library routines that the program may use and creates an executable image, which is also saved on disk, usually as a file with the file name without any extension (e.g. hello). 3. Execute The executable is loaded from the disk to memory and CPU executes the program one instruction at a time. 1.8 Overview of C language It was developed in 1972 by Dennis Ritchie at the Bell telephone laboratories for use with Unix operating system. It was designed for system programming because of its low level memory management and its construct are close to the machine instructions. 1.9 C program structure and syntax Every C program consists of a header and a main body and has the following structure. // Comment statements, which are ignored by computer #include <header file name > Void main() { declaration of variables ; statements ; return 0; } We will consider each line of the above program for convenience the program is reproduced on the next page with line numbers to 13

14 allow us to comment on details of the program. However, you must not put line numbers in an actual program. 1. //sample program 2. #include "stdio.h" 3. void main() 4. { printf ("This is a line of text to output.\n"); 5. } Line 1: At the top of the program are comments and instructions, which will not be executed. Lines beginning with // indicate that the rest of the line is a comment. Comments are inserted by programmers to help people read and understand the program. Here the comment states the purpose of the program. Comments are not executed by the computer. They can in general be placed anywhere in a program. Line 2: Lines beginning with # are instructions to the compiler s pre-processor. They include instruction says what follows is a file name, find that file and insert its contents right here. It is used to include the contents of a file of definitions that may be used in the program. Line 3 The word main is very important, and must appear once (and only once) in every C program. This is the point where Introduction to Programming 14 execution is begun when the program is run. It does not have to be the first statement in the program but it must exist as the entry point. The use of the term main is actually a function definition. Functions must return a value and the term void is used to denote that the main program does not return a value. Following the main program name is a pair of parentheses, which are an indication to the compiler that this is a function. The two braces are used to define the limits of the program itself: in this case, the main function. The actual program statements go between the two braces. Line 4 The opening (left) brace marks the beginning of the main body of the program. The main body consists of instructions, which can be declarations defining the data or statements on how the data should be processed. All C declarations and statements must end with a semicolon. Line 5 printf is a predefined function. To sent output on the monitor, the text is put within the function parentheses and bounded by quotation marks. The definition of this function is defined in the STDIO library (the Standard Input/output library). To compile and link this program the #include statement is required. The end result is that whatever is included between the quotation marks in the

15 printf function will be displayed on the monitor when the program is run. Notice the semi-colon at the end of the line. C uses a semicolon as a statement terminator, so the semi-colon is required as a signal to the compiler that this line is complete. Line 6 The closing (right) brace marks the end of the main body of the program Chapter summary 1.11 Chapter exercise 1.12 Further reading suggestion 15

Unit. Programming Fundamentals. School of Science and Technology INTRODUCTION

Unit. Programming Fundamentals. School of Science and Technology INTRODUCTION INTRODUCTION Programming Fundamentals Unit 1 In order to communicate with each other, we use natural languages like Bengali, English, Hindi, Urdu, French, Gujarati etc. We have different language around