Programming

Question 1

Explain the need for meaningful identifiers

Answer 1

It allows people who are quickly skimming through your code, to see which areas of code correspond to which outputs instead of reading the whole code.

Question 2

Define character

Answer 2

A character is a unit of information

Question 3

What are assemblers used for?

Answer 3

To turn assembly language into machine code

Question 4

Define integer

Answer 4

A data type that represents numerical values such as 10 or 15

Question 5

Give some characteristics of high-level languages

Answer 5

One instruction represents many instructions of machine code
The same code will work for many different machines and processors
The programmer can easily store data in lots of different structures without knowing about the memory structure
Code is easy to read, understand and modify
Must be translated into machine code before a computer is able to understand it
You don’t have much control over what the CPU actually does so programs will be less memory efficient and slower

Question 6

Explain a nested structure

Answer 6

One structure of code written inside another structure of code as a member of that structure

Question 7

Define Boolean

Answer 7

The Boolean data type is a data type that has one of two possible values (usually true or false)

Question 8

Give some characteristics of compilers

Answer 8

Translates all of the source code at the same time and creates one executable file
Only needed once to create the executable file
Returns a list of errors for the entire programs once compiling is complete
Once compiled, the program runs quickly but compiling can take a long time

Question 9

Give some characteristics of low-level languages

Answer 9

One instruction of assembly code usually only represented one instruction of machine code
Usually written for one type of machine or processor and won’t work on any others
The program are needs to know about the internal structure of the CPU and how it manages the memory
Code is very difficult to read, understand and modify
Commands in machine code can be executed directly without the need for a translator
You control exactly what the CPU does and how it uses memory so programs will be more memory efficient and faster

Question 10

Define real

Answer 10

Real numbers are numbers that include fractions/values after the decimal point

Question 11

Give some characteristics of interpreters

Answer 11

Translates and runs the source code one instruction at a time, but doesn’t create one executable file
Needed every time you want to run the program
The interpreter will return the first error it finds and then stop - this is useful for debugging
Programs will run more slowly because the code is being translated as the program is running

Question 12

What are the three types of translators?

Answer 12

Assemblers
Compilers
Interpreters

Question 13

What are compilers and interpreters used for?

Answer 13

To turn high-level code into machine code

Question 14

Explain indefinite iteration

Answer 14

This repeatedly executes a selection of code until a certain condition is met

Question 15

Describe what is meant by data type?

Answer 15

A particular kind of data item, as defined by the values it can take, the programming language used or the operations that can be performed on it

Question 16

Explain definite iteration

Answer 16

A set of instructions repeated a specific number of times

Question 17

Define string

Answer 17

A string is traditionally a sequence of characters either as a constant or some kind of variable

Question 18

Describe selection

Answer 18

It is a programming contract where a section of code is run only if a condition is met

Question 19

Define the term “subroutine”

Answer 19

A set of instructions designed to perform a frequently used operation within a program

Question 20

Advantages of using a subroutine:

Answer 20

Code is easier to read and maintain

Test procedures and functions separately

Increases the reusability of code

Question 21

Purpose of parameters:

Answer 21

They allow us to pass information or instructions into functions and procedures

Question 22

Difference between global and local variables?

Answer 22

Local variables are declared within a function whereas global variables are described outside the function

Local variables are only accessible within the function.

Global variables can be accessed from anywhere within the code

Question 23

Advantages of subroutine

Answer 23

• Decomposes the problem
• they are re-useable so take less lines of code
• Easier to read code
• Each one can be tested individually for better debugging

Question 24

Advantages of local variables

Answer 24

• save memory. As it only exist when the subroutine is running.
• less bugs as it can only be altered by the subroutine it is in, marking it easier to debug
• global variable are harder to trace as they are manipulated by many subroutines