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Comprehensive Review of Strings and Functions in Programming

This lecture provides an in-depth review of strings and functions in programming. It covers essential topics such as how to manipulate strings, the significance of functions, parameters, return statements, and scope. Examples demonstrate practical applications like character extraction, basic encryption methods (e.g., Caesar cipher), and function creation with various return values. The session emphasizes the benefits of functions, proper syntax, and guidelines for effective programming practices. Engage in the philosophy of grouping information to enhance code usability and task management.

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Comprehensive Review of Strings and Functions in Programming

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  1. ITEC 109 Lecture 14/15 Strings + Functions

  2. Review • Strings • What can we do? • Why?

  3. Example • Find the first character in the first name and store it in a string called formatted • Print out “Welcome” then print out the value of formatted then a . then a space then the last name Andrew Ray A. Ray

  4. Background

  5. Methods • Any that you remember? • Caesar • A->C, B->D, etc… • Substitution • Replace A with 7 • Replace E with 3

  6. Sample • What code would you need to write to create this encryption ?

  7. Objectives • Functions • Parameters • Return statements • Scope • Examples

  8. Basics • What is the purpose of functions? • What are the benefits? • What are the downsides?

  9. Visualization Current view of a program New view 0 – x=3; 1 – y=x*2; 2 – printNow(y); Function call Function return

  10. FunctionSyntax • def [Name] (): • def firstFunction(): • Name is just like a variable name • ( begins parameters • ) ends parameters • : begins the code • Tab delimited (function begin / end implied)

  11. Syntax def FunctionName(): printNow(“I am a function”) Function body def FunctionName(): printNow(“I am a function”) FunctionName() Function call

  12. Visualization Step 1: Ignore function def FunctionName(): printNow(“I am a function”) FunctionName() Step 2: Call Function Step 3: Execute Function Print Step 4: Return back to main Step 5: End program

  13. Return • Have a function send info back • 2 way street • Return trip def secretValue(): return 15 myValue = secretValue() printNow(myValue)

  14. Parameters • Provide input to a function • Comma separated list • A copy of other variables • Required when function is called def add(var1,var2): return var1+var2; result = add(3,4) printNow(result)

  15. Scope • Where variables can be used def example(): test=“Hello” printNow(test) test=“apple” example() printNow(test) Is this test the same as this test? Answer: not it isn’t

  16. Rules • Functions are like prisons, you don’t have the freedom to go outside • One way in • Parameters • One way out • Return statement

  17. Example • Writing a function that reads an int, squares, and returns it [Math.pow(var,2)]

  18. Example • Writing a function that performs the quadratic formula

  19. Example • Write two functions that return a separate piece of the of a string • First|Last • getFirst / getLast

  20. Philosophy • Group information together • Make it useful • Subdivide tasks to developers

  21. Review • Functions • Parameters • Return types

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