Function Returns
- 2. THE RETURN STATEMENT• Used to end execution of a function • Can be placed anywhere in a function • Statements that follow the return statement will not be executed • Can be used to prevent abnormal termination of program • A function can return a value or expression back to the statement that called the function. • You've already seen the randint function, which returns a value: x = random.random() • Also many math functions return a value: • exp(x,y); • sqrt(x); • sin(x);, etc. • In a value-returning function, the return statement can be used to return a value from function to the point of call. • assign it to a variable • send it to print • use it in an expression
- 3. FUNCTION WITH RETURN EXAMPLE
- 4. VARIABLE SCOPE: LOCAL AND GLOBAL • Variables defined inside a function are local to that function. They are hidden from the statements in other functions, which normally cannot access them. When the function terminates the values are released. • Because the variables defined in a function are hidden, other functions may have separate, distinct variables with the same name. • Question: What does the above statement mean?
- 5. LOCAL VARIABLES • A function’s local variables exist only while the function is executing. This is known as the lifetime of a local variable. • When the function begins, its local variables and its parameter variables are created in memory, and when the function ends, the local variables and parameter variables are destroyed. • This means that any value stored in a local variable is lost between calls to the function in which the variable is declared.
- 6. GLOBAL VARIABLES AND GLOBAL CONSTANTS • A global variable is any variable defined outside all the functions in a program. • The scope of a global variable is the portion of the program from the variable definition to the end. • This means that a global variable can be accessed by all functions that are defined after the global variable is defined. Bad Programming: The use of global variables Good Programming: Only creating global variables that are constant