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

3. printf Function printf( output_format ,[value_list] );
General format for printf function:
printf( output_format ,[value_list] );
output_format tells 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 Programming

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

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 Programming

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 Programming

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

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

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

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

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

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

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

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

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

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

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

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

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

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

21. 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);}
age ? 21
height ?
1.73
Ali is 21 years old and his height is meters _
TK1913-C Programming

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 Programming

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

24. scanf Function ? 16 12 2005 Example: day month year
#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); }
month ?
year
day 16 12
2005
Day: 16, Month: 12, Year: 2005_
TK1913-C Programming

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

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