CS Key Terms Flashcards
Iteration
A block of code is executed repeatedly, either until a condition is met or for a set number of times.
Statement
Any individual step/instruction in the code
Assignment
Assignment is used to set the value of a variable, e.g. x := 5; (Usually described as X becomes equal to 5). The variable is written on the left and the value on the right. Do not confuse this with the equalities operator seen below.
Serial files
Data is stored in the file in the order in which it was entered. New data is appended to the end of the file.
Sequential files
The data is sorted according to a key field. New data is inserted in the correct position.
Watches/variable checks
Outputting the value of variables at specified points in the program, or when they change.
Translator diagnostics
Messages generated by the translator when converting the code to executable code. Helpful in finding syntax errors and some logic errors. Sometimes the line the error is reported on is not accurate.
Logic error
The code as it is written does something which is different from what the programmer intended. Usually detected while testing, as the program produces an incorrect result.
String
Textual data in the form of a list of characters, for example words and punctuation. String data is made up of character data and will usually vary in length.
Sequence
Executes each statement once, in the order in which it is given.
Subroutines
A sub-program, a set of statements written to perform a given task as part of solving the main problem. It can be called using its identifier.
Function
Specifically a subroutine which returns a single value and can therefore be used as if it were a variable.
Parameter/argument
Data item being supplied to a function or procedure when it is called
Pseudo code
A method of writing an algorithm using normal language which will mimic the programming code, but without worrying about specific syntax. It is useful for planning programs or explaining them to other people.
Indentation
Every time a new line of code is placed within a programming construct, e.g. If statement, the code should be intended to show that it exists within that structure. This makes it clear where each structure starts and finishes.
Initialising variables
This means giving variables a starting value, to ensure it starts at the right value or doesn’t hold a junk value from memory. Typically 0, “” or false, although could be a more specific value depending on the program.
Syntax error
The statement in the code does not follow the rules of the language. Usually detected by the translator, as the statement cannot be understood and translated.
Run-time error
The program attempts an impossible operation (such as division by zero, accessing a missing file, etc.). Usually detected while testing, as the program crashes.
Stepping
Executing the code a line at a time after a break point has been specified. Useful to check variables and see what individual lines of code are doing to locate logical errors.
Dry run
The programmer goes through the code line by line as the computer would, often using a trace table to keep track of variables to check that the code performs as expected.
Break points
Causing the program to halt at a specified marker. The programmer can then check the values of variables, and step through the code (execute the code one line at a time).
Reserved words
Words which are reserved for a specific purpose in the programming language, e.g. IF… WHILE… DO…
Commenting
Explaining a section of code with normal language in order to make it more understandable for other people. Comments should be made when the code is written and not after it has been written.
Procedure
A subroutine which performs a task, but has no return value
Transparency
Transparency in code is achieved by giving variables, constants, functions and procedures suitable names. This makes it easier for someone else to read the code and understand the purpose of those features.
Boolean
Can only hold two possible values e.g. True or False, Yes or No
Variable
The identifier associated with a particular memory location used to store data. By using a variable you can store, manipulate and retrieve data without knowing what the data will be, e.g. var x := integer
Time
Used to store only real Times e.g. 12:42 but not 25:61
Date
Used to store only real Dates e.g. 20/01/2010 but not 32/14/2011
Char
Any single character represented by the codes from the character set in use on the computer.
Integer
Any whole number, negative or positive e.g. 1, 34, 234564, -14 (there is a maximum value for each computer)
Equality
Used to check whether two values are equal e.g. x = 5 (Described as x is equal to 5). This would usually be seen as a condition in an IF statement or the end condition of a loop.
Array
An array contains several items of data, of the same type, grouped under one identifier. Each item in the array (element) has an index which allows that specific element to be access.
Recursion
Recursion is when a subroutine (a procedure or a function) calls itself. The recursive subroutine is executed as normal until it gets to the line where it calls itself. At this point the subroutine is paused and a new call to the same subroutine is started. This will continue until an end condition is reached or the computer runs out of memory.
Nesting
Placing one or more programming constructs inside another.
Identifier
The specific name of a variable, procedure or function within a program
Selection
A comparison determines whether a block of code will be executed or not. Examples: if statement, case/switch statements
Constant
A data item with a fixed value. It cannot be changed when the program is executed, e.g. const pi := 3.1416
Real
Any number represented with a fractional part, e.g. 3.1416, -123.34
