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PseudoCode Cheat Sheet (DRAFT) by

Pseudo code

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Data Types

STRING
INTEGER
REAL
BOOLEAN
CHARACTER

Arithmetic Operators

Addition: +
Division: /
Subtra­ction: –
Remainder: MOD
Multip­lic­ation: *
Integer Division: DIV

Other

Assignment operator: = Don’t confuse = with == (they’re different)
You can use true and false to check Boolean variables in your conditions (as in IF SomeBo­ole­anV­ariable == true THEN …etc.)
Variables are not loosely typed – you can’t mix different types of variable They don’t seem to have to be declared, although sometimes there’ll be a declar­ation (If you’re asked to declare something, you can pretty much just make it up – as long as it specifies the data type, identi­fier, etc…)
Sometimes a colon is used to identify the data type of a variable, e.g. SomeVa­riable : REAL would declare a real (decimal) variable
Keywords are in capitals in pseudocode
Arrays work as they do in most languages, but often their index starts at 1, rather than 0, and sometimes they use parent­hesis ( ) instead of brackets [ ]
Multid­ime­nsional arrays work like this: identi­fier(y, x)

Constructs

IF condition THEN
    do something
ELSE
    do something else
END IF

WHILE condition
    statements
END WHILE

REPEAT
    statements
UNTIL condition
The else bit is optional – you don’t have to have it
The condition is any expression that evaluates to a Boolean
Notice how the statements are indented (well, hopefully they’ll display indented when I publish this…)
When using WHILE and REPEAT loops, to count, you need to manually initialize and increment the counting variable
The statements inside a loop should cause a change in one of the values in the condition, otherwise you may create an infinite loop
  

Procedure & Functions

PROCEDURE doSomething(Parameter : DATATYPE, OtherParameter: DATATYPE)
    statements
END PROCEDURE

FUNCTION doSomething(parameter: DATATYPE) : RETURNTYPE
    statements
RETURN something
END PROCEDURE
Procedures and functions don’t have to take parame­ters, but the parent­heses () are necessary
Functions must have a return type and must return something (of that type)
File Handling

For

FOR i = 1 to 10
    statements
NEXT i
END FOR
With a FOR loop, increm­enting and initia­lizing of the counting variable are done automa­tically
You can call the counting variable (i, in this case) anything you want, and you can also set the = something TO something values to whatever you want it to count from and to

Relational / Comparison Operators

Equal to: ==
Not equal to: !=
Not equal to: <>
Greater than: >
Less than: <
Greater than or equal to: >=
Less than or equal to: <=
Both: AND
One or both: OR
Invert: NOT
Logical / Boolean Operators

CASE

CASE OF something
    something = this: statement
    something = that: statement
    something = other: statement
    default: statement
END CASE
In a case statement (that’s switch statement to Java/C# people) you can have however many options you want, but there must always be a default for if none of the options match
In the example above, something is the variable that is being checked, and this, that and other are things it’s being compared with
  

String Manipu­lation

There are two functions that look things up in the ASCII character set table for you:
ASCII(­cha­racter) returns the ASCII value of a character, character
CHAR(i­nteger) returns the character of an ASCII value, integer
Characters may be in single or double quotes (it’s another thing the examiners don’t seem to have made their minds up about)
Strings can be concat­enated using the addition operator, +
You sometimes have to use concat­enation to output something in a friendly way
Mathem­atics can’t be done on strings, but you can compare their ASCII values using the relational operators (<, >, <>, !=, ==, >=, <=)
MID(st­ring, integer1, integer2) returns the part of the string between positions integer1 and integer2
LEFT(s­tring, integer) RIGHT(­string, integer) LENGTH­(st­ring) returns the length of the string, string
LOCATE­(st­ring1, string2) returns the position of the first occurrence of string2 in string1 (0 means it starts at the beginning, -1 means it’s not in there)
I don’t know why these functions are acting like there are official pseudocode libraries… they must just be for inspir­ation, and as a guide

File Handling

OPEN filename FOR MODE
(You can open as READ or WRITE only, one at a time)
READ extrac­ted­var­iable FROM filename
WRITE something TO filename
CLOSE filename
DELETE filename
RENAME filename TO something
CREATE filename
“filename is at end of file” can be used in the condition of loops, to iterate through all the records

High-Level Questions

 
Occasi­onally, you’ll be asked to write something in a real language
I think the course does require you to be taught the basics of a high-level procedural progra­mming language in the first year
Again, though, the questions are more about unders­tanding what to do than following the correct syntax
Famili­arise yourself with how to write the constructs above in a high-level language (i.e. not assembly…)