Program Design: Flowcharts and Pseudocode

• This chapter covers designing programs, output, input, variables, assignment, calculations, declarations, data types, named constants, tracing, documenting, and initial program design.

Designing a Program

• The first step in programming involves designing the logic via flowcharts and pseudocode.
• After design, the code is written and cleared of syntax errors.
• Once the executable is created, it is checked for logic errors, which necessitate debugging.
• Programming Logic and Design focuses on Flowcharts and Pseudocode as the foundation of a good program.
• Designing a program involves understanding the required tasks and determining the necessary steps.
• An algorithm, or step-by-step directions, solves the problem and is implemented using flowcharts or pseudocode.
• Pseudocode is a "fake" code model for programs, that does not adhere to syntax rules, but is easily translated.
• Flowcharts are diagrams that graphically depict program steps.
  • Terminators indicate the start and stop points.
  • Parallelograms represent input and output.
  • Rectangles represent processes.

Output, Input, and Variables

• Output is data that a program generates and displays.
• Input is data that a program receives.
• Output, Input and variables are key elements in programming design.
• A typical computer program follows the steps of receiving input, processing it, and producing output.
• Display is used to show output on the screen.
• Sequence executes lines in the order they appear.
• String Literals represent a sequence of characters.
• Input keyword takes values from the user and stores them in variables.
• Programmers define variable names following rules.
  • They must be one word without spaces.
  • Punctuation characters are generally avoided.
  • The first character cannot be a number.
  • The variable name to describe the stored data.
• camelCase is a popular naming convention.

Variable Assignment & Calculations

• Variable assignment can come from user input or be set through an assignment statement.
• Calculations use math operators and the result is stored in variables:
  • + is addition operator.
  • - is subtraction operator.
  • * is multiplication operator.
  • / is division operator.
  • MOD is modulus operator.
  • ^ is exponent operator.

Variable Declarations & Data Types

• A variable declaration includes a variable's name and data type.
• Data type defines the kind of data a variable can store.
  • Integer stores whole numbers.
  • Real stores whole or decimal numbers.
  • String stores any series of characters.
• Variables should be initialized to 0 or some other value for safety.

Named Constants

• A named constant is a name that represents a value that cannot be changed, making programs self-explanatory.
• If a value needs to be changed, it only has to be modified in one place.
• Example: Constant Real INTEREST_RATE = 0.069

Hand Tracing a Program

• Hand tracing serves as a debugging process for finding hard-to-locate errors.
• It involves creating a chart with a column for each variable and a row for each line of code.

Documenting a Program

• External documentation describes aspects of the program for the user.
• Internal documentation explains how parts of the program work for programmers, known as comments.
• Comments in the program are displayed with line comments i.e // comment on the code

Designing Your First Program

• Designing a program involves determining what input is needed, how to process it, and what the output should be, as shown in the batting average calculation example.
• Consider input (hits, at-bats), process (calculating the batting average), and output (the player's batting average).
• Input involves determining the necessary data and choosing variables.
• Processing involves setting the calculations to be performed and choosing variables.
• The output determines display and calculations.