A flowchart is a diagram that visually represents the steps in a process. It uses standard symbols to show the flow of control and decision points. Flowcharts are invaluable for planning and documenting algorithms, making them easier to understand and debug.
Key Flowchart Symbols
Here's a breakdown of the most common flowchart symbols:
Oval (Start/End): Represents the beginning and end of the process.
Rectangle (Process): Represents a specific action or operation.
Diamond (Decision): Represents a point where a decision needs to be made, usually resulting in two or more possible paths.
Parallelogram (Input/Output): Represents data being entered into or output from the process.
Arrow (Flow Line): Indicates the direction of the process flow.
Circle (Connector): Used to connect different parts of the flowchart, especially when the flow continues on the same or a different page.
Flowchart Construction Rules
Start with an oval symbol.
Use rectangles for each process step.
Use diamonds for decisions. Each diamond should have at least two outgoing arrows, one for each possible outcome.
Use parallelograms for input and output operations.
Connect the symbols with arrows to show the flow of control.
Ensure that each decision has a clear path for each outcome.
Use connectors to link parts of the flowchart if necessary.
Types of Flowcharts
There are different types of flowcharts, each suited for different purposes:
Process Flowchart: Shows the sequence of steps in a process.
Decision Flowchart: Illustrates the different paths based on decisions.
Structure Flowchart: Represents the structure of a program (e.g., a sequence of instructions).
Example: Calculating the Area of a Rectangle
Let's create a flowchart to calculate the area of a rectangle.
Suggested diagram: A flowchart showing inputting length and width, calculating area, and outputting the result.
Symbol
Description
Oval
Start
Parallelogram
Input Length
Parallelogram
Input Width
Rectangle
Calculate Area: Area = Length x Width
Parallelogram
Output Area
Oval
End
Arrow
Flow Line
Decision Diamonds in Detail
Decision diamonds are crucial for representing conditional logic. They typically have two or more outgoing arrows, each labeled with a possible outcome (e.g., "Yes" and "No", or "True" and "False"). The flowchart should clearly indicate which path to follow based on the condition.
Algorithm and Flowchart Relationship
An algorithm is a step-by-step procedure for solving a problem. A flowchart is a visual representation of an algorithm. You can often create a flowchart directly from an algorithm, or vice versa. This relationship is fundamental to problem-solving in computer science.
Practice
Practice creating flowcharts for simple algorithms like: