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Constructs
Programming constructs are the fundamental instructions that tell a computer what to do and in what order. They are the basic building blocks for creating any algorithm, just like a recipe is built from simple steps.
Need to know
What you need to know
- `IF...THEN...ELSE...ENDIF`: Used for single or binary choices. The `ELSE` part is optional. You can chain them using `ELSEIF` for multiple conditions.
- `CASE...OF...OTHERWISE...ENDCASE`: Ideal for selecting one path from many, based on the value of a single variable or expression. It's often cleaner than multiple `ELSEIF`s.
- Nested Selection: An `IF` or `CASE` statement can be placed inside another one to handle more complex, multi-level conditions.
- Conditions use relational operators (`=`, `<>`, `<`, `>`, `<=`, `>=`) and logical operators (`AND`, `OR`, `NOT`).
Explanation
The Algorithm's Recipe Book
- **Sequence:** Code runs line by line, in the order it's written, like following a simple list of instructions.
- **Selection (IF/CASE):** The program makes a decision. It checks a condition and chooses which block of code to run next.
- **Iteration (Loops):** A block of code is repeated. This can be a set number of times (`FOR`), while a condition is true (`WHILE`), or until a condition becomes true (`REPEAT`).
- **Nesting:** Constructs can be placed inside one another. For example, a loop (`FOR`) might contain a decision (`IF`) to handle different cases on each repetition.