Pseudocode (College Board)

Pseudocode

Paradigm(s)	imperative, procedural
Designed by	College Board
Appeared in	Before 2018
Type system	static
Memory system	variable-based
Dimensions	one-dimensional
Computational class	Turing complete
Reference implementation	None

Pseudocode is a programming language designed by College Board for the AP Computer Science Principles course. Pseudocode was created to provide language-agnostic examples and exam questions.

Syntax

Pseudocode has two official representations; textual and block. The formats are presented together on exams and in examples.

Standard functions:

DISPLAY (expr)
INPUT ()
RANDOM (a, b)

DISPLAY is effectively equivalent to the Python code print(expr, end=" "). RANDOM includes both ends.

Assignment is done with

var ← expr

expr can be an arithmetic expression containing procedure calls, operators, etc. The arithmetic operators are +, -, *, / (not floor division), MOD (only positive arguments). Comparison operators are =, ≠, >, <, ≥, ≤. Connectives are NOT, AND, OR. Expressions can be parenthesized for precedence.

List literals are [v1, v2, ...] and a list variable l would be indexed like l[i] with the first valid i being 1. Lists can be modified with the functions INSERT (l, i, v) shifts list elements to accomodate an empty position at l[i and sets it to v, APPEND (l, v) extends the list and puts v at the end, REMOVE (l, i) deletes the element l[i] and shifts later elements back, LENGTH (l) returns the length of the list.

Conditionals can be either

IF (expr)
{
   code
}

Or

IF (expr)
{
   code
}
ELSE
{
   code
}

While loops are in the form:

REPEAT UNTIL expr
{
   code
}

With count loops being:

REPEAT n TIMES
{
   code
}

No variable is assigned for count loops.

Loop iteration:

FOR EACH v IN l
{
   code
}

The variable v is assigned to each value of l.

Functions are defined like:

PROCEDURE name (p1, p2, ...)
{
    code
}

Where p1 and so on are the untyped parameter names. code is arbitrary code, which may include the RETURN (expr) statement anywhere, which immediately returns from the function with a value if encountered.

The language also has a turtle system which is used via the commands:

MOVE_FORWARD() // one unit
ROTATE_LEFT() // 90 degrees
ROTATE_RIGHT() // 90 degrees
CAN_MOVE(dir) // left, right, forward, backward

Movement is 1 unit, rotations are 90°, dir can be left, right, forward, or back.

See also

• Coral (zyBooks)

External links

• APCSP CREATE GitHub repo Online demo
• APScript GitHub repo Online demo
• College Board Pseudocode Interpreter GitHub repo Online demo
• JavaScript to Pseudocode Transpiler GitHub repo Online demo