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Pseudo Code - 1

COMP108 Lectures

Algorithms

An algorithm is a precise and concise set of instructions that guide you to solve a specific problem in a finite amount of time.

graph LR
Input --> Algorithm
Algorithm --> Output

The differences between algorithms and programs are as follows:

  • In algorithms the content is more important than the form.
  • Algorithms are free from grammatical Rules.
  • Programs must follow syntax rules.
    • Form is important.

Pseudo Code

This is a logical code that doesn’t strictly follow the syntax of any individual programming language. They are useful for drafting algorithms.

Pseudo code uses a combination of english and code to make it more human readable.

Control Flow

The following conventions for pseudo code are preferred:

if <condition> then
	<statement>
else
	<statement>

for <variable> <- <value1> to <value2> do
	<statement>

while <condition> do
	<statement>

Blocks

Block in control sequences should be laid out like so:

begin
	<statement1>
	<statement2>
	.
	.
	.
end

or:

{
	<statement1>
	<statement2>
	.
	.
	.
}

Operations

  • The % operator can be used in place of mod.

Other Notes

The use of a boolean variable to mark a significant event is called a flag variable. You can use this to mark a condition that has been met.

It is recommended that you draw a trace table of all the values at each iteration to find logical errors in your algorithms. You can also use them to find out what an algorithm does.