GCSE (9-1): Computer Science: AQA: Structured Programming

• Iteration

  A piece of code that repeats, a loop. One of the four main programming constructs, we use WHILE or FOR to code it

  
• Selection

  When the code makes a choice, usually with an "IF" statement. One of the four main programming constructs

  
• Sequence

  Two or more lines of code that are executed in order, top to bottom. One of the four main programming constructs

  
• Subroutine

  A section of code that performs a particular task, a function or procedure, one of the four main programming constructs
• variable

  A named memory location holding a value that can change during a program, it can be global or local
• function

  A type of subroutine that executes a block of code and then returns a value
• procedure

  This subroutine executes a block of code that performs a useful process but does not return a value
• global

  Variables of this type remain in memory even when a subroutine ends, their scope is the whole program
• local

  Variables with limited scope, they are usually deleted when the subroutine ends, thus saving memory and preventing errors
• scope

  The portion of a program in which a local variable is usable, usually the subroutine where it is declared
• parameter

  A variable declared in a subroutine definition, a and b are parameters in this code:SUBROUTINE add(a, b) result ← a + b RETURN resultENDSUBROUTINE
• Call

  A line of code that causes a subroutine to run by using its name, for example answer ← add(2, 3) will run the function "add" and store the result in the variable "answer"
• Structured programming

  Dividing a task into smaller tasks before coding, and writing each sub-task as a subroutine. It makes debugging and maintenance easier