6: Conditional Execution

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6.1: Conditional Execution
6.2: If - Else
We are going to introduce the control structure from the selection category that is available in every high level language. It is called the if then else structure. Asking a question that has a true or false answer controls the if then else structure.
- 6.2.1: Conditional Execution - If-Else
6.3: Boolean Data Type
The Boolean data type is also known as the logical data type and represents the concepts of true and false. The name "Boolean" comes from the mathematician George Boole; who in 1854 published: An Investigation of the Laws of Thought.
6.4: Relational Operators
The relational operators are often used to create a test expression that controls program flow. This type of expression is also known as a Boolean expression because they create a Boolean answer or value when evaluated. There are six common relational operators that give a Boolean value by comparing (showing the relationship) between two operands.
6.5: Compound Statement
For illustration we will use the syntax for the if then else control structure within the C++ programming language. However this problem generally exists for all control structures within any language that requires the use of compound statements.
6.6: Ternary operator
6.7: Nested If Then Else
As you can see we simply included as part of the "true action" a statement and another if then else control structure. We did the same (nested another if then else) for the "false action". In our example we nested if then else control structures. Nesting could have an if then else within a while loop. Thus, the concept of nesting allows the mixing of the different categories of control structures.
6.8: Logical Operators
Within most languages, expressions that yield Boolean data type values are divided into two groups. One group uses the relational operators within their expressions and the other group uses logical operators within their expressions.
6.9: Case Control Structure
One of the drawbacks of two way selection is that we can only consider two choices. But what do you do if you have more than two choices.
6.10: Branching Control Structures
The branching control structures allow the flow of execution to jump to a different part of the program. The common branching control structures that are used with other control structures are: break, continue and goto. These are rarely used in modular structured programming with one exception. That exception is in relation to creating the case within the selection category of control structures.