2.2.1 Programming Techniques Flashcards
Component 2 (17 cards)
What is a variable?
- Identifier of a memory location used to store data
- Used to store a value which can change during execution
What are the global variables?
- The variable can be accessed throughout the scope of the program (visible throughout a program)
- Using passing by reference is an equivalent of a global variable.
What are the negatives of global variables?
- Uses more memory - memory is declared when the program starts and remains in use throughout.
- Testing more difficult - it is difficult to test an individual block of code.
- Reduces data accuracy - Changing a global variable may have an impact on another module.
What are the positives of global variables?
- Simpler to program - values do not need to be passed between different subroutines.
- Do not need to worry about returning values - all parts of the program can access the value.
What is a local variable?
Can only be accessed within the scope of the sub-program where it is created
A parameter that is passed into a subroutine becomes a local variable in the subroutine e.g. LoadLevel(Difficulty)
What is an IDE?
Integrated Development Environment (IDE) - A program used for developing programs, made from several components.
What tools are provided by an IDE to develop software?
- Auto-complete – Will predict variable and built-in functions and finish off the word. Can avoid spelling mistakes and speed up development
- Syntax highlighting (colour coding text) - Can distinguish between different features quickly to check code is correct
- Auto Indent – Indents code automatically within structures to avoid errors
What tools are provided by an IDE to debug software?
- Error highlighting - Syntax errors highlight dynamically so they can be corrected before running the program (saving time)
- Variable Watch window – Display the values of the variables during running of the program
- Break points- Stop the program at set points to check the values of variables. Developer can add multiple breakpoints.
- Error message list- Tells you where errors are and suggests corrections
- Stepping - Executes program one line at a time to watch variable values and program pathways
- Traces - Printouts of variable values for each statement execution
What are the three programming constructs?
- Sequence
- Selection / Branching
- Iteration
What is an example of a count controlled loop?
FOR Loop - Will run for a set number of predetermined times.
What is an example of a condition controlled loop?
WHILE / DO WHILE - Will run whilst a condition is true or false
What are parameters?
Parameters are the variables listed between the brackets, after the procedure/function name e.g.
They become local variables in the routines that they are passed to.
characterMovement(inputKey, characterx, charactery)
What does passing by value mean?
By Value (ByVal)
* Does not override the original data
* A local copy of the data is used
* Data is discarded when the subprogram exits
What does passing by reference mean?
By Reference (ByRef)
* Changes are made to the original data
* Memory location of data is sent
* Changes remain after the subprogram exits
* Uses less memory
What is a function?
- A named block of code which always returns a value
- Uses the keyword return
- Assigns the returned value to a variable (e.g. y)
What is a procedure?
- A named block of code which does not return a value
- Does not use the keyword return
- Is called by writing its name but not assigning the result to a variable
What are the benefits of modularity in coding?
Breaking code down into functions / procedures / scripts
- Write once and call repeated times - Avoids repeated code
- Small sub-programs are easier to read/understand/modify
- Can be tested individually and then added to the main program.
- Can be reused in other programs
- Can give sub-routines to different programmers to build concurrently
