7 Methods: A Deeper Look [2014Q2-ME2008]

7.1   Introduction 7.2   Packaging Code in C# 7.3   static Methods, static Variables and Class Math 7.4   Declaring Methods with Multiple Parameters 7.5   Notes on Declaring and Using Methods 7.6   Method Call Stack and Activation Records 7.7 Argument Promotion and Casting 7.8 The Framework Class Library 7.9   Case Study: Random-Number Generation 7.9.1 Scaling and Shifting Random Numbers 7.9.2 Random-Number Repeatability for Testing and Debugging 7.10   Case Study: A Game of Chance (Introducing Enumerations) 7.11   Scope of Declarations

7.12   Method Overloading 7.13   Recursion 7.14   Passing Arguments: Pass-by-Value vs. Pass-by-Reference 7.15   (Optional) Software Engineering Case Study: Identifying Class Operations in the ATM System 7.16   Wrap-Up

Fig. 7.2 | Math class methods.

Outline MaximumFinder.cs (1 of 2)

Outline MaximumFinder.cs (2 of 2)

Outline MaximumFinderTest. cs

Fig. 7.5 | Implicit conversions between simple types.

Outline RandomIntegers.cs (1 of 2)

Outline RandomIntegers.cs (2 of 2)

Outline RollDie.cs (1 of 3)

Outline RollDie.cs (2 of 3)

Outline RollDie.cs (3 of 3)

Outline RandomIntegers.cs (1 of 2)

Outline RandomIntegers.cs (2 of 2)

Outline RollDie.cs (1 of 3)

Outline RollDie.cs (2 of 3)

Outline RollDie.cs (3 of 3)

Error-Prevention Tip 7.2 While an application is under development, create the Random object with a specific seed value to produce a repeatable sequence of random numbers each time the application executes. If a logic error occurs, fix the error and test the application again with the same seed value—this allows you to reconstruct the same sequence of random numbers that caused the error. Once the logic errors have been removed, create the Random object without using a seed value, causing the Random object to generate a new sequence of random numbers each time the application executes.

Outline Craps.cs (1 of 4)

Outline Craps.cs (2 of 4)

Outline Craps.cs (3 of 4)

Outline Craps.cs (4 of 4)

Outline CrapsTest.cs (1 of 2)

Outline CrapsTest.cs (2 of 2)

Good Programming Practice 7.3 Use only uppercase letters in the names of constants. This makes the constants stand out in an application and reminds you that enumeration constants are not variables.

Good Programming Practice 7.4 Using enumeration constants (like Status.WON, Status.LOST and Status.CONTINUE) rather than literal integer values (such as 0, 1 and 2) can make code easier to read and maintain.

Outline Scope.cs (1 of 2)

Outline Scope.cs (2 of 2)

Outline ScopeTest.cs

Outline MethodOverload.cs

Outline MethodOverload.cs

Outline MethodOverload.cs

Outline FactorialTest.cs (1 of 2)

Outline FactorialTest.cs (2 of 2)

Common Programming Error 7.11 Either omitting the base case or writing the recursion step incorrectly so that it does not converge on the base case will cause infinite recursion, eventually exhausting memory. This error is analogous to the problem of an infinite loop in an iterative (nonrecursive) solution.

Performance Tip 7.1 Pass-by-reference is good for performance reasons, because it can eliminate the pass-by-value overhead of copying large amounts of data.

Software Engineering Observation 7.5 Pass-by-reference can weaken security, because the called function can corrupt the caller’s data.

Outline ReferenceAndOutput Parameters.cs (1 of 2)

Outline ReferenceAndOutput Parameters.cs (2 of 2)

Outline ReferenceAndOutput ParamtersTest.cs

Common Programming Error 7.12 The ref and out arguments in a method call must match the parameters specified in the method declaration; otherwise, a compilation error occurs.

Software Engineering Observation 7.6 By default, C# does not allow you to choose whether to pass each argument by value or by reference. Value-types are passed by value. Objects are not passed to methods; rather, references to objects are passed to methods. The references themselves are passed by value. When a method receives a reference to an object, the method can manipulate the object directly, but the reference value cannot be changed to refer to a new object. In Section 8.8, you’ll see that references also can be passed by reference.

Fig. 7.20 | Verbs and verb phrases for each class in the ATM system.

Fig. 7.21 | Classes in the ATM system with attributes and operations.

Fig. 7.22 | Class BankDatabase with operation parameters.

Fig. 7.23 | Class Account with operation parameters.

Fig. 7.24 | Class Screen with an operation parameter.

Fig. 7.25 | Class CashDispenser with operation parameters.