Transcript Compute the Costs

Top-down design
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Outline the project in the boldest steps
possible, do not worry about how to achieve
each step
 It is to be expected that some steps are beyond
your immediate understanding
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Consider each step, refine it as much as
possible, go to another step if you run into
trouble
If you are dealing with a computer program,
continue to refine until the steps are program
language commands
Example 1: opening a
restaurant
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Choose a Theme
Pick a neighborhood
Find a Site
Compute the Costs
Acquire the Funds
Build it
Get the Staff
Prepare the Ads
Compute the Costs
- Hire an architect, get
the building costs
- Determine costs of
utilities, trash
removal, etc.
- Evaluate Labor Costs
- Evaluate Publicity
Costs
Example 2: merging files
• Consider a large file of names and phone
numbers
– a telephone directory for a large city
• Consider a smaller file of new names and phone
number which must be added to the original list
– new phone numbers added today
• Design a procedure (a program?) that will merge
these two files into a new phone directory
Example 2: merging files
1. Alphabetize OLDLIST
2. Alphabetize ADDLIST
3. Create a blank file, call it NEWLIST
4. Merge OLDLIST and ADDLIST into NEWLIST
5. Delete OLDLIST
6. Delete ADDLIST
7. Rename NEWLIST, calling it OLDLIST
Example 2: merging files
1. Alphabetize OLDLIST
(already done, it was yesterday’s output.)
2. Alphabetize ADDLIST
(learn how to sort stuff, too much trouble to
describe here.)
3. Create a blank file NEWLIST
(easy to do…)
Example 2: merging files
4. Merge OLDLIST and ADDLIST into NEWLIST
A. read the first item of OLDLIST, call it OLD,
read the first item of ADDLIST, call it ADD
B. compare OLD with ADD, write the smaller of
them to NEWLIST, read the next item to replace
it.
C. if you have not run out of file OLDLIST or
ADDLIST, return to B again, otherwise go to D.
D. If you have drained ADDLIST, read the rest of
OLDLIST into NEWLIST, if you have drained
OLDLIST, read the rest of ADDLIST into
Example 2: merging files
5. Delete OLDLIST
6. Delete ADDLIST
7. Rename NEWLIST, calling it OLDLIST
Two parts of a function definition
int Cube ( int n )
{
return n * n * n;
}
Heading
• The heading declares the function’s
name, specifying its return type and
the name and type of each of its
parameters
• The body is a compound statement
(block) which defines the behavior of
Body