QBasic

1
QBasic

• Chapter 2 Introduction to Structured
  Programming Problem Solving

2
Programming Languages

• Machine Language
• Only language computer can execute directly
• Difficult for humans to write in 1s and 0s
• Different for each type of computer
• Assembly Language
• Operations specified in symbolic names
• Also different for each type of computer
• Difficult time consuming

3
Programming Languages

• High-Level Languages
• Do not require knowledge of hardware
• Programs are mostly portable
• Must be translated
• QBasic translates automatically
• Versions called Dialects

4
Structured Programming

• Easy-to-follow logic
• Modules
• Perform specific tasks
• QBasic calls them Procedures
• Three Basic Control Structures
• Sequence
• Decision / Selection
• Loop

5
The Programming Process

• Process of solving problems
• Define document the problem
• Design document a solution
• Write document the program
• Debug test the program
• Make revisions in program documentation if
  necessary

6
Defining Documenting the Problem

• Need a clear concise problem statement
• Write it down!
• Describe input output

7
Designing Documenting a Solution

• Develop the algorithm
• Steps must be in correct order
• Top-Down Design
• Solve the major problem first
• Focus on the details later
• Divide problem gradually smaller sub-problems

8
Designing Documenting a Solution

• Structure Charts / Hierarchy Charts
• Flowcharts
• Pseudocode

9
Writing Documenting a Program

• Write or Code the solution in a programming
  language
• Desk Check first
• Thoroughly document the program

10
Debugging Testing a Program

• Locate correct program errors
• Syntax Errors
• Run-time Errors
• Logic Errors