computer science: a structured programming approach using c1 4-6 scope scope determines the region...

Computer Science: A Structured Programming Approach Using C 1

4-6 Scope

Scope determines the region of the program in which a Scope determines the region of the program in which a defined object is visible. Scope pertains to any object defined object is visible. Scope pertains to any object that can be declared, such as a variable orthat can be declared, such as a variable ora function declaration. a function declaration.

Global ScopeLocal Scope

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FIGURE 4-32 Scope for Global and Block Areas

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Variables are in scope from declaration until the end of their block.

NoteNote

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It is poor programming style to reuse identifiers within the same scope.

NoteNote

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4-7 Programming Example— Incremental Development

Top–down development, a concept inherent to Top–down development, a concept inherent to modular programming, allows us to develop programs modular programming, allows us to develop programs incrementally. By writing and debugging each incrementally. By writing and debugging each function separately, we are able to solve the program function separately, we are able to solve the program in smaller steps, making the whole process easier.in smaller steps, making the whole process easier.

First Increment: main and getDataSecond Increment: addFinal Increment: Print ResultsThe

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FIGURE 4-33 Calculator Program Design

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PROGRAM 4-13 Calculator Program—First Increment

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PROGRAM 4-13 Calculator Program—First Increment

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PROGRAM 4-13 Calculator Program—First Increment

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PROGRAM 4-14 Calculator Program—Second Increment

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PROGRAM 4-14 Calculator Program—Second Increment

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PROGRAM 4-14 Calculator Program—Second Increment

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PROGRAM 4-14 Calculator Program—Second Increment

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PROGRAM 4-15 Calculator Program—Final Increment

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PROGRAM 4-15 Calculator Program—Final Increment

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PROGRAM 4-15 Calculator Program—Final Increment

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PROGRAM 4-15 Calculator Program—Final Increment

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4-8 Software Engineering

In this section we discuss three different but related In this section we discuss three different but related aspects of software engineering design: the structure aspects of software engineering design: the structure chart, functional cohesion, and top–down development.chart, functional cohesion, and top–down development.

Structure ChartsStructure Chart RulesFunctional CohesionTop–Down Development

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FIGURE 4-34 Structure Chart Symbols

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FIGURE 4-35 Structure Chart Design

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Structure charts show only function flow; they contain no code.

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FIGURE 4-36 Common Functions in a Structure Chart

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Table 4-1 Structure Chart Rules

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FIGURE 4-37 Calculate Taxes Design

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FIGURE 4-38 Design For Print Report

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PROGRAM 4-16 Top–down Development Example

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PROGRAM 4-16 Top–down Development Example

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PROGRAM 4-16 Top–down Development Example