motivation complexity of programming problem more difficult to consider the solution as a whole ...
TRANSCRIPT
Motivation
• Complexity of programming problem more difficult to consider the solution as a whole clue: dividing the problem into small parts (module)
• Each module represent single task, free of error
• Modularisation : is the process of dividing a problem into separate tasks, each with a single purpose.
Benefits of modular design
• Ease of understandingeach module has only one function
• Reusable code
• Elimination of redundancy avoid the repetition of writing
• Efficiency of maintenance
Modular name convention
• Describe the work to be done as a single specific function
• Use a verb, followed by a two-word object.
• Example:– Print_page_heading– Calculate_sales_tax– Validate_input_date
Example 8.1
• Design a solution algorithm that will prompt a terminal operator for three characters, accept those characters as input, sort them into ascending sequence and output them to the screen. The algorithm is to continue to read characters until ´XXX´is entered.
• Defining diagram
Input Processing Output
Char_1Char_2Char_3
Prompt for charactersAccept three charactersSort three charactersOuput three characters
Char_1Char_2Char_3
Original Solution algorithmProcess_three_characters
Prompt the operator for char_1, char_2, char_3Get char_1, char_2, char_3DOWHILE NOT (char_1=´X`AND char_2=´X´AND char_3=´X´)
IF char_1>char_2 THENtemp = char_1char_1 = char_2char_2 = temp
ENDIFIF char_2>char_3 THEN
temp = char_2char_2 = char_3char_3 = temp
ENDIFIF char_1>char_2 THEN
temp = char_1char_1 = char_2char_2 = temp
ENDIFOutput to the screen char_1, char_2, char_3Prompt operator for char_1, char_2, char_3Get char_1, char_2, char_3
ENDDOEND
Solution Algorithm using a moduleProcess_three_characters
Prompt the operator for char_1,char_2,char_3Get char_1, char_2, char_3DOWHILE NOT (char_1=´X`AND char_2=´X´AND char_3=´X´)
Sort_three_charactersOutput to the screen char_1,char_2,char_3Prompt operator for char_1, char_2, char_3Get char_1,char_2,char_3
ENDDOEND
Sort_three_charactersIF char_1>char_2 THEN
temp = char_1char_1 = char_2char_2 = temp
ENDIF IF char_2>char_3 THEN
temp = char_2char_2 = char_3char_3 = temp
ENDIFIF char_1>char_2 THEN
temp = char_1char_1 = char_2char_2 = temp
ENDIFEND
´Controlling module´or´Calling module´or ´Mainline“
`Subordinate module` or `Called Module`
Hierarchy Chart Example 8.1
Process_three_characters
Sort_three_characters
Calling module
Called module
Example 8.2 Process three characters
Design a solution algorithm that will prompt a terminal operator for three characters, accept those characters as input, sort them into ascending sequence and output them to the screen. The algorithm is to continue to read characters until ´XXX´is entered.
• Defining diagram
Input Processing Output
Char_1Char_2Char_3
Prompt for charactersAccept three charactersSort three charactersOuput three characters
Char_1Char_2Char_3
Solution AlgorithmProcess_three_characters
Read_three_charactersDOWHILE NOT (char_1=´X`AND char_2=´X´AND char_3=´X´)
Sort_three_charactersPrint_three_charactersRead_three_characters
ENDDOEND
Read_three_charactersPrompt the operator for char_1,char_2,char_3Get char_1, char_2, char_3
END
Sort_three_charactersIF char_1>char_2 THEN
temp = char_1char_1 = char_2char_2 = temp
ENDIF IF char_2>char_3 THEN
temp = char_2char_2 = char_3char_3 = temp
ENDIFIF char_1>char_2 THEN
temp = char_1char_1 = char_2char_2 = temp
ENDIFEND
Print_three_charactersOutput to the screen char_1, char_2, char_3
END
Mainline
1rst Module
2nd Module
3rd Module
Hierarchy charts
Process_three_characters
Read_three_characters
Sort_three_characters
Print_three_characters