CS Key Terms

A block of code is executed repeatedly, either until a condition is met or for a set number of times.

Any individual step/instruction in the code

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.

Data is stored in the file in the order in which it was entered. New data is appended to the end of the file.

The data is sorted according to a key field. New data is inserted in the correct position.

Outputting the value of variables at specified points in the program, or when they change.

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.

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.

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.

Executes each statement once, in the order in which it is given.

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.

Specifically a subroutine which returns a single value and can therefore be used as if it were a variable.

Data item being supplied to a function or procedure when it is called

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.

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.

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.

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.

The program attempts an impossible operation (such as division by zero, accessing a missing file, etc.). Usually detected while testing, as the program crashes.

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.

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.

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).

Words which are reserved for a specific purpose in the programming language, e.g. IF… WHILE… DO…

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.

A subroutine which performs a task, but has no return value