COMP1000 Week 6

  • Introduction to Functions:
    • Functions are named blocks of code designed to perform specific tasks.
    • The execution of code jumps to the function when it's called and returns upon completion.
  • How Functions Work:
    • When a function is called, the program control shifts to the function's code block.
    • After the function completes its task, control returns to the line immediately following the function call.
  • Structure of a Function:
    • Functions typically consist of three main parts:
      • Return Type
      • Function Name
      • Parameters
  • Return Type:
    • Specifies the type of value the function will return after execution.
    • Can be void if the function does not return any value.
    • If a data type is specified (e.g., int, float, string), a return statement is required.
  • Function Name:
    • A user-defined name for the function, similar to variable names.
    • Used to call or invoke the function in the code.
  • Parameters:
    • Values passed into the function, specified within parentheses.
    • The number and type of parameters must match the function definition when the function is called.
    • Parameters are optional; a function may have no parameters.
  • Writing a Function:
    • Example: A function that prints "hello".
      • Return type: void (since it only prints and doesn't return a value).
      • Name: sayHello.
      • No parameters.
      • Body: println("hello").
  • Function Definition vs. Function Call:
    • Definition: The actual code of the function, defining what it does.
    • Call: Invoking the function by its name to execute its code.
  • Passing Values to Functions:
    • Values are passed as parameters in the function call.
    • These values are used within the function to perform operations.
  • Returning Values from Functions:
    • If a function has a return type (not void), it must return a value of that type.
    • The return statement specifies the value to be returned.
  • Example: Function to Add Two Numbers:
    • Takes two numbers as parameters.
    • Adds the numbers together.
    • Returns the sum.
    • Code:
      • int addNumbers(int a, int b) {
      • int sum = a + b;
      • return sum;
      • }
  • Importance of Return Type:
    • The data type of the returned variable must match the return type specified in the function declaration.
  • Variable Scope:
    • Variables declared inside a function are local to that function.
    • They cannot be accessed outside the function unless returned.
  • Advantages of Using Functions:
    • Modularity: Breaks down code into manageable, reusable blocks.
    • Code Reusability: Allows the same code to be used multiple times.
    • Readability: Makes code easier to understand and maintain.