Python Basic-day9-function

• Programming method
  • 1, process-oriented programming: According to business logic from top to bottom code to implement the function
  • 2, functional programming: to encapsulate a function code in the function, the use of the same function later, no need to write, direct function calls can
  • 3. Object-oriented programming: classify and encapsulate functions to make development "faster, better and stronger"
• function-type programming
  • function definition
    • will be able to implement some kind of function, reusable, organized code block together
  • Functions of the function
    • Enhanced reusability and readability of code
  • function syntax
    • def function name (parameter optional)
      • function body (code block)
      • Return
  • The function returns the value return
    • The result returned to the caller after the function has been executed (the caller is required to accept by defining the variable)
    • The function ends when it encounters a return, no longer executes the following code, ends the function
      • Do not write return, Python built-in rules return none by default
      • Return None, returning none
      • Return a single value that returns this single value
      • Return multiple values, including multiple values in (tuples), returned to the caller (can be directly accepted by defining the deconstruction)
  • function Parameters
    • Parameter: A variable in the position of a function declaration that declares a variable in parentheses
      • Position parameters
      • Default parameters
        • 1. The positional parameter must be declared before the default parameter can be declared
    • Argument: The value that the caller actually passes to the function when it invokes the function
      • Position parameters
      • Keyword parameters
      • Mixed parameters
        • 1, position parameters and keyword parameters mixed use
        • 2, must first write positional parameters, after the keyword parameters, or error: (syntaxerror:positional argument follows keyword argument)
  • Ternary op-expression
    • A = 1
    • b = 2
    • c = A If a > b Else B # C equals if A is greater than B, and no is equal to B

Python Basic-day9-function