Understanding Computer Programs: File Structure, Interaction, and Programming, Slides of Information and Computer Technology

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Chapter 12A

Creating Computer Programs

What Is a Computer Program?

• Computer programs
  • Also called software
  • Are a list of instructions
  • Instructions are called code
  • CPU performs the instructions
  • Three types
    • Operating system
    • Utility
    • Application 13A-

Software Is Stored In Many Files

• Dynamic link libraries
  • Partial executable file
  • Used to support executable files
  • Have .dll extensions 13A-

Software Is Stored In Many Files

• Initialization files
  • Contain configuration settings for software
  • Have a .ini extension
  • Modern programs use the registry 13A-

Software Is Stored In Many Files

• Batch files
  • Used to automate tasks
  • Hold a series of OS commands
  • Have a .bat extension 13A-

Hardware/Software Interaction

• Program execution
  • Software executes at the CPU level
  • Code to play a sound
    • Code generates an interrupt
    • CPU tells the sound card to play
    • Sound card plays the file
  • Programmer creates the code 13A-

Writing Code

13A-

Hardware/Software Interaction

• Machine code
  • Recall that computers think in binary
  • Code is translated into machine code
    • CPU executes the machine code
  • CPUs have a unique machine code 13A-

Hardware/Software Interaction

• Compilers and interpreters
  • Converts source code into binary
    • Allows code to execute
  • Checks source code for correctness 13A-

Hardware/Software Interaction

• Compiler
  • Creates an executable file
    • Contents are called object code
  • Executable can run on its own
  • Each language has its own compiler
  • C++ and Java are compiled languages 13A-

Planning a Computer Program

• Plans
  • The steps to solve a problem
  • Describe the expected results
  • Programming without a plan is difficult 13A-

Planning Tools

• Pseudo code
  • Natural language statements that resemble code
  • Describes what must be done
  • Can be written by non programmers
  • Programmers develop unique versions 13A-

IPO Chart

13A-

How Programs Solve Problems

• Program control flow
  • Order program statements are executed
  • Typically executed in order
  • Constructs can change the flow
    • Decision statements
    • Loops 13A-