Data:
- Constants and Variables
- Data used in problem solving
Constants:
- A constant is a specific alphabetical and/or numerical value that never changes during the processing of all the instructions in the solution
- Constants can be any type of data – numeric, alphabetical, etc.
- In many programming languages and applications constants can be named
- In this case, the constant is given a location in memory and a name
- Once the constant is given a value, it cannot be changed during the execution of the program, e.g., the value of PI.
- The only way to change the value of a constant is to change the program.
- Many name conventions stipulate that named constants be given names containing ALL CAPITAL LETTERS in order to easily distinguish them from variables.
Variables:
- The value of a variable may change during processing
- In many languages variables are called identifiers since the name identifies what the value represents
- The programmer uses variable name as a reference name for a specific value of the variable
- The computer sets up a specific memory location to hold the value of each variable name found in the program
- The variable name should be consistent with what the value of the variable represents.
Rules for naming the variables:
- Name the variable according to what it represents
- Do not use spaces in the variable names
- Start a variable name with a letter
- Do not use hyphens or special symbols except underscore
- Be consistent when using upper and lowercase letters
- Use the exact variable name when referencing that variable in any part of the program
- Use the exact variable name when referencing that variable in any part of the program
- Use the naming conventions specified by the organization where you work, e.g. all uppercase letters for constants and first uppercase letter for every word used in variable name.
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