Input and Output

1. FTSM Input and Output Knowledge: Understand various types of input and output syntaxes Skill: Develop a program to read/capture input and display output Computer Science Department

2. Input and Output • There are various functions available in C library that can be used for input and output activities. The two functions that will be explained here are printf() and scanf() • printf() function is used for displaying characters on output devices (normally video display) • scanf() function is used for reading/capturing characters from input devices (normally keyboard) TK1913-C Programming2

3. printfFunction • General format for printf function: printf( output_format ,[value_list] ); • output_formattells function about the format that should be followed when displaying output • value_list is a list of variables, constants, expressions or combination of them, which values are parts of the displayed output TK1913-C Programming3

4. What does \n mean? printf Function Example: printf(“TK1913 C Programming\n\n”); printf(“List of Students\n”); printf(“Ahmad bin Ali”); TK1913 C Programming List of Students Ahmad bin Ali _ TK1913 C Programming _ TK1913 C Programming List of Students _ TK1913-C Programming4

5. printf Function • printf() function can be used to display values of variable, constant and others • To display a value, the format of the value has to be stated in the output_format. For example, the position of the value when the output is displayed TK1913-C Programming5

6. printf Function Formats for displaying output values: • %s for string • %c for character • %d for integer • %f for float/double • %e for float/double (scientific notation) TK1913-C Programming6

7. Output format Value (a string constant) Output format Value (an array of characters) Output format printf Function - String Format for string: %s • Example: • printf( “%s” , “Display a string\n” ); • Similar to: • printf( “Display a string\n” ); Normally, it is used to display an array of characters • Example: • char name[ ] = “Nadiah”; • printf( “%s” , name ); TK1913-C Programming7

8. Output format printf Function - String • Example: printf( “Name: %s\nStudent No: %s”, “Ali Bakar”, “A92333”); Name: Ali Bakar Student No: A92333_ TK1913-C Programming8

9. printf Function - String • Example: printf( “Name: %s\nStudent No: %s”, “Ali Bakar”, “A92333”); Name: Ali Bakar Student No: A92333_ TK1913-C Programming9

10. printf Function - Character Format for character: %c • Example: • printf(“%c %c %c”, ‘U’, ‘K’, ‘M’); U K M_ TK1913-C Programming10

11. printf Function - Character • Example: • printf(“%c%c%c”, ‘U’, ‘K’, ‘M’); UKM_ TK1913-C Programming11

12. char1 char2 char1 char1 char2 char3 char3 char3 char2 U U ? ? U K ? K M printf Function - Character • Example: • char1 = ‘U’; • char2 = ‘K’; • char3 = ‘M’; • printf(“%c %c %c”, char1, char2, char3); U K M_ TK1913-C Programming12

13. 6 digits 10 characters printf Function - Integer • Format for integer: %d • General format: • %[<min_field_width>.<min_digit>]d • Example: • printf(“Value is:%10.6d”, 56342); Value is: 056342 TK1913-C Programming13

14. 5 digits Min 3 digits 10 characters printf Function - Integer • Example: • printf(“Value is:%10.3d”, 56342); Value is: 56342 TK1913-C Programming14

15. Min 4 characters 5 characters printf Function - Integer • Example: • printf(“Value is:%10.4d”, 56342); Value is:56342 TK1913-C Programming15

16. 4 digits 10 characters printf Function - Float • Format for float: %f • General format: • %[<min_field_width>.<decimal_places>]f • Example: • printf(“Value is:%10.4f”, 32.6784728); Value is: 32.6784 TK1913-C Programming16

17. 6 digits (default) 10 characters printf Function - Float • Example: • printf(“Value is:%10f”, 32.6784728); Value is: 32.678473 TK1913-C Programming17

18. 5 digits 10 characters printf Function - Float • Example: • printf(“Value is:%10.5f”, 32.6784); Value is: 32.67840 TK1913-C Programming18

19. 6 digits (default) 9 characters Min 5 characters printf Function - Float • Example: • printf(“Value is:%5f”, 32.6784728); Value is:32.678473 TK1913-C Programming19

20. 3 digits printf Function - Float • Example: • printf(“Value is:%.3f”, 32.6784728); Value is:32.678 TK1913-C Programming20

21. age ? height ? printf Function - Float • Example: • #include <stdio.h> • void main( ) { • int age; • float height; • age = 21; • height = 1.73; • printf(“Ali is %d years old and his height is %.5f meters\n”, age, height);} 21 1.73 Ali is 21 years old and his height is 1.73000 meters _ TK1913-C Programming21

22. scanf Function • General format for scanf function: scanf( input_format , list_of_variables ); • input_format tells function about the format that should be followed when capturing data • list_of_variables are locations in memory, in which the captured data is kept • input_format should contain specification of each intended input data • User needs to key-in data based on the format and specification set by the program TK1913-C Programming22

23. char ? num ? Key-in a character and a number: scanf Function • Example: • printf(“Key-in a character and a number: “); • scanf(“%c%d”, &char, &num); • printf(“Character: %c\n”, char); • printf(“Number: %d\n”, num); m 103 Key-in a character and a number: m103 Key-in a character and a number: m103 Character: m _ Key-in a character and a number: m103 Character: m Number: 103 _ TK1913-C Programming23

24. day ? month ? year ? scanf Function • Example: • #include <stdio.h> • void main( ) { • int day, month, year; • scanf(“%d %d %d”, &day, &month, &year); • printf(“Day: %d, Month: %d, Year: %d”, day, month, year); • } 16 12 2005 16 12 2005 16 12 2005 Day: 16, Month: 12, Year: 2005_ TK1913-C Programming24

25. Conclusion & Discussion • Your Project • Any problem during lab and tutorial sessions?? TK1913-C Programming25

26. Yes !! That’s all? What’s next??? OPERATORS & EXPRESSIONS on the way … End of Lecture 5 TK1913-C Programming26