Crash Course In Computer Coding

The building blocks of computer coding regardless of language (Ada, Basic, C, Fortran, Pascal) are: declaration statements, conditional statements and loop statements.

Declaration Statements: Examples

A = expression;
C = sin(value);
B = CalculateSpeed(parameters);
D = E;

Conditional Statements: Examples

If (some test) Then {statement1; statement 2;...statement N};

If (some test) Then {statement1; statement 2;...statement N}
Else {statement1;....statement n};

Case or Switch (some variable)
{
case (variable 1): statement1;...statement n;
case (variable 2): statement1;...statement n;
...
case (variable n): statement1;...statement n;
}

Loop Statements: Examples

For (some test) repeat {statement1; statement2;...statement n};

While (expression) do { statement1; statement2;...statement n};

Do {statement1; statement2;...statement n;} Until (expression);

Routines

Computer code perform multiple operations. Closely related operations are lumped together into a routine to improve manageability of code. The relationship between operations is called cohesion.

There are six levels of acceptable cohesions between operations in a routine; Functional, Sequential, Communicational, Temporal, Procedural and Logical.

Function Cohesion

This is the best kind of routine. It performs one and only operation. Examples: sin(), cos()... GetLocation().

Sequential Cohesion

This the second best routine. It is used when closely related operations share the same data operations and must be performed is a specific order. Example: OpenFile(), ReadFile(), PrintFile() and CloseFile().

Communicational Cohesion

This routine is used when unrelated operations make use of the same data. Example: GetNameAndChangePhoneNumber(), GetAddressAndName(), SaveNameAndPhoneNumber().

Temporal Cohesion

This routine is used to combine unrelated operations done at the same time. Example: StartUp(), ShutDown(), Suspend(), Resume() Initalize(), GetInterruptStatus().

Procedural Cohesion

This routine is used when closely related operations don't share the same date. Example: PrinRevenueReport(dataX), PrintExpenseReport(dataY), ListEmployeePhoneNumbers(DataZ).

Logical Cohesion

This routine is used when only one of the operations is selected by a control flag. all the operations are in a big If or Case statement. Example: InputAll(flag), ComputeAll(flag), EditAll(flag), PrintAll(flag) and Save(flag).

Coupling

Coupling is the complement of cohesion. Cohesion describes how strongly the internal operations are related in a routine. Coupling describes how strongly a routine is related to other routines.

Good coupling between routines is loose enough that any routine can easily be called by other routines. Routines should depend very little on other routines. For Example, a routine like sin() is loosely coupled because everything it needs to know is passed to it with a value representing an angle.

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