Functions, procedures and random numbers

Overview

Sub programs, functions and procedures, parameters and return values, local and global variables, worked function results, and random number generation.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   What is a sub program?

   Model answer

   A sub program is a named block of code that carries out one task. The main program calls it by name whenever the task is needed.

2. 2

   What is the difference between a function and a procedure?

   Model answer

   A function returns a value to the code that called it. A procedure carries out its task without returning a value.

3. 3

   What is a parameter?

   Model answer

   A parameter is a variable that receives a value when a sub program is called. The value is passed in the brackets after the sub program's name.

4. 4

   What is output by print(triple(7)), given function triple(n), return n * 3, endfunction?

   Model answer

   The code outputs 21. The function returns 7 × 3, and print displays the returned value.

5. 5

   What is output by greet("Mo"), given procedure greet(name), print("Hello " + name), endprocedure?

   Model answer

   The procedure outputs Hello Mo. The argument "Mo" is passed into the parameter name and joined to the text Hello.

6. 6

   Why is a function's return value often stored, as in total = addVAT(price)?

   Model answer

   A variable keeps the returned value so the program can use it again later. A value that is only printed is lost once that line has run.

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