MT258 Computer Programming and Problem Solving

1. MT258Computer Programming andProblem Solving Unit 1

2. Important points • Method for calculating the final grade. • The procedure for requesting of extensions. • The procedure for handing in TMAs. • Programming style.

3. Contents • Course Outline • Questions and Answers • Revision of Unit 1 • Questions and Answers • What to do next?

4. Course Overview • Basics of writing programs 4 weeks • Loops and logic 5 weeks • Data and structures 4 weeks • Break-down and build-up 5 weeks • Abstract data and hidden code 4 weeks • Search and order 4 weeks • Divide and conquer 4 weeks • Building lists and trees 4 weeks • From algorithms to problem solving 4 weeks • Revision 2 weeks

5. Study Material • Course Material (Unit 1 - 9) (Blue Books) • Text Book • C How to Program

6. TEXT BOOK • Deitel/Deitel C HOW TO PROGRAM Prentice Hall

7. Reference Book • Angela Shiflet Problem Solving in C Including Breadth and Laboratories West • Kruse, R.L., Leung, B.P., and Tondo, C.L. Data Structures and Program Design in C (2nd Edition). Prentice Hall

8. Reference Book • Herbert Schildt The Complete Reference (3rd Edition) Osborne McGraw-Hill

9. Reference Book (recommended by Celia) • Brian W. Kernighan, Dennis M. Ritchie The C Programming Language Prentice Hall Software Series

10. On line Reference • MT258 SUPPLEMENT http://learn.ouhk.edu.hk/~mt258/mt258/MT258MainFrame.htm • Self Study Centre • Supplementary notes • Errata to Study Units • Study Units • Perform Laboratory • Specimen Examination paper • Specimen TMA

11. Online Reference • OLE • Discussion board

12. How to Success • Follow course schedule • Fully understand • Blue books • Submit TMA on time • Study TMA solution

13. UNIT ONE

14. History of Programming Language and C

15. Writing Your First Prgram Body

16. First Program Body #include <stdio.h> void main() { printf(“Hello. I am a C program. “); printf(“My name is Celia.\n”); printf(“Nice to meet you. I will be your friend for life. :) \n”); printf(“You may press Enter to bye\n”); fflush(stdin); getchar(); } Hello. I am a C program. My name is Celia. Nice to meet you. I will be your friend for life. :) You may press Enter to bye Semicolon

17. Second Program declares a variable #include <stdio.h> void main() { int age; printf(“My name is Celia. Tell me your age: “); scanf(“%d”, &age); printf(“Oh! You are only %d\n”, age); printf(“Very young! ;) \n”); printf(“You may press Enter to bye\n”); fflush(stdin); getchar(); } My name is Cee. Tell me your age: 20 Oh! You are only 20 Very young! ;) You may press Enter to bye input statement output statement

18. Overview of basic elements in C • Output • Output of a program may be directed to the user through the screen, an external device such as a printer, or another program. • Input • It allows users to give data to programs and receive results. Input may also come from an external device such as the network, or another program. • Variables • Variables allow data to be temporarily stored in memory. A variable lives as long as the program lives.

19. Variable • They are typed for storing different value types. a piece of memory for storing data within the program. • The data will disappear when the program terminates. • They should be declared before use. • They should initialized; otherwise the value is undefined. • They have precision and range limits. The precision and range limits of various types are dependent on the computer and operating system.

20. Variables • The declaration has two parts. • The type of the variable. • The name that identifies the variable – Identifier.

21. Data types • char • short int • unsigned int • int • unsigned long • long • float • double • long double • no string • no Boolean

22. Activity 1 • Name any 4 fundamental data types of C.

23. Activity 1 • Name any 4 fundamental data types of C. • int • float • double • char

24. Identifier • the name that identifies the variable. • arbitrary names given to functions, variables, user-defined data types, and so on. • unique in the program that no other programming component would share the same name.

25. Rules concerning the identifier • Identifiers can be up to 31 characters in length. • An identifier must begin with a letter or an underscore. • After the initial letter, subsequent characters may be the letters a to z and A to Z, the underscore character "_", and the digits 0 to 9. • Identifiers are case-sensitive. • No keyword may be used as a variable identifier.

26. Keywords in C • auto default float register struct volatile • break do for return switch while • case double goto short typedef • char else if signed union • const enum int sizeof unsigned • continue extern long static void

27. Activity 2 • Which of the following variable identifiers are invalid ? • const • a* • xchar • b_ • cont • 3phases • enum • num • profit+tax • NuMbEr

28. Activity 2 • Which of the following variable identifiers are invalid ? • const (invalid) • a* (invalid) • xchar (valid) • b_ (valid) • cont (valid) • 3phases (invalid) • enum (invalid) • num (valid) • profit+tax (invalid) • NuMbEr(valid)

29. Using variables in your programs • declaring a variable of a certain type • setting a value to a variable • getting the value from a variable

30. Variables declaration & initialisation • Declaration examples : • int aInteger; • float aRealNumber; • char aChar; • Before a variable is being initialized or assigned to a value, its value is undefined. • Initialisation examples : • int aInteger; or int aInteger = 3 ; • aInteger = 3; • char aChar = ‘c’; • (single quote is a character) • char aChar = “c”; (Not correct) • (double quote is a string) • char x[10]="computer";

31. Variable Precision • caused by assignment from one type to another type • float aFloat = 3.6; • int aInteger; • aInterger = aFloat; • (value in aInterger will be 3 instead of 3.6) • caused by limited precision of the type • float aFloat = 3.141592612345 • (value in aFloat will be 3.141593) • caused by limited in storing values to most primitive data types, machine and operating system dependent.

32. Program Example #include <stdio.h> void main() { char aChar = ‘B’; printf(“The value of aChar is %c\n”, aChar); printf(“The ASCII value of aChar is %d\n”, aChar); printf(“The value of ‘B’ is %c\n”, ‘B’); printf(“The ASCII value of ‘B’ is %d\n”, ‘B’); fflush(stdin); getchar(); } The value of aChar is B The ASCII value of aChar is 66 The value of ‘B’ is B The ASCII value of ‘B’ is 66

33. Program Example #include <stdio.h> void main() { char aChar = 66; printf(“The value of aChar is %c\n”, aChar); printf(“The ASCII value of aChar is %d\n”, aChar); fflush(stdin); getchar(); } The value of aChar is B The ASCII value of aChar is 66

34. Program Example #include <stdio.h> void main() { char firstChar = ‘1’; char secondChar; secondChar = firstChar; printf(“The value of secondChar is %c\n”, secondChar); printf(“The ASCII value of secondChar is %d\n”, secondChar); fflush(stdin); getchar(); } The value of secondChar is 1 The ASCII value of secondChar is 49

35. Program Example #include <stdio.h> void main() { int firstInt; float secondFloat; firstInt = 9.8; printf(“Value of firstInt is %d\n”, firstInt); secondFloat = 123.4567890123456789; printf(“Value of secondFloat is %f\n”, secondFloat); fflush(stdin); getchar(); } Value of firstInt is 9 Value of secondFloat is 123.456787

36. Program Example #include <stdio.h> void main() { float lowFloat; double doubleFloat; lowFloat = 123.4567890123456789; doubleFloat = 123.4567890123456789; printf(“Value of lowFloat is %.16f\n”, lowFloat); printf(“Value of doubleFloat is %.16f\n”, doubleFloat); fflush(stdin); getchar(); } Value of lowFloat is 123.4567871093750000 Value of doubleFloat is 123.4567890123456806

37. Program Example #include <stdio.h> void main() { int anInt = 123456789012345; printf(“Value of anInt is %d\n”, anInt); fflush(stdin); getchar(); } Value of anInt is -2045911175

38. Program Example #include <stdio.h> #include <limits.h> void main() { printf(“Maximum value of char = %d\n”, CHAR_MAX); printf(“Minimum value of char = %d\n”, CHAR_MIN); printf(“Maximum value of int = %d\n”, INT_MAX); printf(“Minimum value of int = %d\n”, INT_MIN); printf(“Maximum value of long = %d\n”, LONG_MAX); printf(“Minimum value of long = %d\n”, LONG_MIN); fflush(stdin); getchar(); } Maximum value of char = 255 Minimum value of char = 0 Maximum value of int = 2147483647 Minimum value of int = -2147483648 Maximum value of long = 2147483647 Minimum value of long = -2147483648

39. Program Example #include <stdio.h> #include <float.h> void main() { printf(“Precision of float = %.16f\n”, FLT_EPSILON); printf(“Precision of double = %.16f\n”, DBL_EPSILON); printf(“Maximum value of float = %e\n”, FLT_MAX); printf(“Minimum value of float = %e\n”, FLT_MIN); printf(“Maximum value of double = %e\n”, DBL_MAX); printf(“Minimum value of double = %e\n”, DBL_MIN); fflush(stdin); getchar(); } Precision of float = 0.0000001192092896 Precision of double = 0.0000000000000002 Maximum value of float = 3.402823e+38 Minimum value of float = 1.175494e-38 Maximum value of double = 1.797693e+308 Minimum value of double = 2.225074e-308

40. Output • printf • function - writes formatted output to stdout • syntax - #include<stdio.h> • printf(const char*format[,argument,….]) • some input argument • %d - int • %f - float and double • %e - prints in exponential format, eg 1.23e5 • %c – ASCII standard

41. Output • Example of printf • #include <stdio.h> • int main(void) • { • int x; • x = 3; • printf(“Variable x is assigned as %d\n”,x); • return 0; • }

42. Output (Holding the screen) • getch • Function : gets character from keyboard, does not echo to screen. • Syntax : #include <conio.h> • int getch(void); • getchar • Function : gets character from stdin. • Syntax : #include <stdio.h> • int getchar(void); • fflush • syntax : #include <stdio.h> • int fflush(FILE *stream) • eg. fflush(stdin)

43. Output (Holding the screen) • example : • #include <stdio.h> • int main(void) • { int x; • printf(“please enter x: “); • scanf (“%d”,&x); • fflush(stdin); • printf(“The number is %d\n”,x); • getchar(); • return 0; • }

44. Output • Escape sequence • the backslash character (\) is used to introduce an escape sequence, allowing the visual representation of certain nongraphic characters.

45. Output • Some available escape sequences • \n newline • \t horizontal tab • \v vertical tab • \a audible sound • \b backspace • \f form feed • \r carriage • \\ backslash • \” double quote • \’ single quote • \0 null value

46. Program Example #include <stdio.h> void main() { printf(“Hello. I am Cee. \n”); printf(“Nice to show you how output is done in C\n”); } Hello. I am Cee. Nice to show you how output is done in C

47. Program Example #include <stdio.h> void main() { printf(“My personal information\n”); printf(“Name\t\t: Cee\n”); printf(“Sex\t\t: Computer is asexual\n”); printf(“Age\t\t: Modern\n”); printf(“Interests\t: Playing CDs, talking to printers, defragmentation\n”); fflush(stdin); getchar(); } My personal information Name : Cee Sex : Computer is asexual Age : Modern Interests : Playing CDs, talking to printers, defragmentation

48. Input • scanf • function - scans and formats input from the stdin stream • syntax - #include<stdio.h> • scanf(const char*format[,address,….]) • some input argument • %d • %f • %c

49. Input • Example of scanf • #include <stdio.h> • int main(void) • { • int x; • printf(“Please enter an integer\n :”); • scanf(“%d”,&x); • printf(“Variable x is assigned as %d\n”,x); • return 0; • }

50. Program Example #include <stdio.h> void main() { char aChar; printf(“Enter a characters: “); aChar = getchar(); printf(“The character entered is %c\n”, aChar); printf(“Enter a characters: “); aChar = getchar(); printf(“The character entered is %c\n”, aChar); printf(“Press Enter to bye\n”); fflush(stdin); getchar(); } Enter a characters: C The character entered is C Enter a characters: The character entered is Press Enter to bye