tailieunhanh - Top-Down Design
If we look at a problem as a whole, it may seem impossible to solve because it is so complex. Examples: o writing a tax computation program o writing a word processor • Complex problems can be solved using top-down design, also known as stepwise refinement, where o We break the problem into parts o Then break the parts into parts o Soon, each of the parts will be easy to do | Top-Down Design Topics Top-Down Design Top-Down Design Examples The Function Concept Reading Sections , Top-Down Design If we look at a problem as a whole, it may seem impossible to solve because it is so complex. Examples: writing a tax computation program writing a word processor Complex problems can be solved using top-down design, also known as stepwise refinement, where We break the problem into parts Then break the parts into parts Soon, each of the parts will be easy to do Advantages of Top-Down Design Breaking the problem into parts helps us to clarify what needs to be done. At each step of refinement, the new parts become less complicated and, therefore, easier to figure out. Parts of the solution may turn out to be reusable. Breaking the problem into parts allows more than one person to work on the solution. An Example of Top-Down Design Problem: We own a home improvement company. We do painting, roofing, and basement waterproofing. A section of town has recently . | Top-Down Design Topics Top-Down Design Top-Down Design Examples The Function Concept Reading Sections , Top-Down Design If we look at a problem as a whole, it may seem impossible to solve because it is so complex. Examples: writing a tax computation program writing a word processor Complex problems can be solved using top-down design, also known as stepwise refinement, where We break the problem into parts Then break the parts into parts Soon, each of the parts will be easy to do Advantages of Top-Down Design Breaking the problem into parts helps us to clarify what needs to be done. At each step of refinement, the new parts become less complicated and, therefore, easier to figure out. Parts of the solution may turn out to be reusable. Breaking the problem into parts allows more than one person to work on the solution. An Example of Top-Down Design Problem: We own a home improvement company. We do painting, roofing, and basement waterproofing. A section of town has recently flooded (zip code 21222). We want to send out pamphlets to our customers in that area. The Top Level Get the customer list from a file. Sort the list according to zip code. Make a new file of only the customers with the zip code 21222 from the sorted customer list. Print an envelope for each of these customers. Main Sort Select Print Read Another Level? Should any of these steps be broken down further? Possibly. How do I know? Ask yourself whether or not you could easily write the algorithm for the step. If not, break it down again. When you are comfortable with the breakdown, write the pseudocode for each of the steps (modules) in the hierarchy. Typically, each module will be coded as a separate function. Structured Programs We will use top-down design for all remaining programming projects. This is the standard way of writing programs. Programs produced using this method and using only the three kinds of control structures, sequential, selection and repetition, are called structured .
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