AP Computer Science Principles Exam Reference Sheet

AP CSP Exam

Reference Sheet

AP COMPUTER SCIENCE PRINCIPLES

Effective

Fall 2020

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Exam Reference Sheet

Instruction Explanation

Assignment, Display, and Input

Tex t :

a ← expression

Block:

expression

Evaluates expression and then assigns a copy of the result to

the variable

Tex t :

DISPLAY(expression)

Block:

DISPLAY expression

Displays the value of expression, followed by a space.

Tex t :

INPUT()

Block:

INPUT

Accepts a value from the user and returns the input value.

Arithmetic Operators and Numeric Procedures

Text and Block:

a + b

a - b

a * b

a / b

The arithmetic operators +, -, *, and / are used to perform

arithmetic on

a and b.

For example,

17 / 5 evaluates to 3.4.

The order of operations used in mathematics applies when evaluating

expressions.

Text and Block:

a MOD b

Evaluates to the remainder when a is divided by b. Assume that

a is an integer greater than or equal to 0 and b is an integer

greater than

For example,

17 MOD 5 evaluates to 2.

The

MOD operator has the same precedence as the * and /

operators.

Tex t :

RANDOM(a, b)

Block:

RANDOM a,

Generates and returns a random integer from a to b, including

a and b. Each result is equally likely to occur.

For example,

RANDOM(1, 3) could return 1, 2, or 3.

Relational and Boolean Operators

Text and Block:

a = b

a ≠ b

a > b

a < b

a ≥ b

a ≤ b

The relational operators =, ≠, >, <, ≥, and ≤ are used to test

the relationship between two variables, expressions, or values. A

comparison using relational operators evaluates to a Boolean value.

For example,

a = b evaluates to true if a and b are

equal; otherwise it evaluates to

false.

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Instruction Explanation

Relational and Boolean Operators (continued)

Tex t :

NOT condition

Block:

NOT condition

Evaluates to true if condition is false; otherwise

evaluates to

false.

Tex t :

condition1 AND condition2

Block:

condition1 condition2AND

Evaluates to true if both condition1 and condition2

are true; otherwise evaluates to false.

Tex t :

condition1 OR condition2

Block:

condition1 OR condition2

Evaluates to true if condition1 is true or if

condition2 is true or if both condition1 and

condition2 are true; otherwise evaluates to false.

Selection

Tex t :

IF(condition)

{

}

Block:

IF condition

block of statements

The code in block of statements is executed if the

Boolean expression

condition evaluates to true; no

action is taken if

condition evaluates to false.

Tex t :

IF(condition)

{

<rst block of statements>

}

ELSE

{

}

Block:

IF condition

first block of statements

ELSE

second block of statements

The code in rst block of statements is executed

if the Boolean expression

condition evaluates to true;

otherwise the code in

second block of statements is

executed.

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Instruction Explanation

Iteration

Tex t :

REPEAT n TIMES

{

}

Block:

REPEAT n TIMES

block of statements

The code in block of statements is executed n times.

Tex t :

REPEAT UNTIL(condition)

{

}

Block:

REPEAT UNTIL

block of statements

condition

The code in block of statements is repeated until the

Boolean expression

condition evaluates to true.

List Operations

For all list operations, if a list index is less than 1 or greater than the length of the list, an error message is produced and the program

terminates.

Tex t :

aList ← [value1, value2, value3, ...]

Block:

aList valuel, value2, value3

Creates a new list that contains the values value1, value2,

value3, and ... at indices 1, 2, 3, and ...

respectively and assigns it to aList.

Tex t :

aList ← []

Block:

aList

Creates an empty list and assigns it to aList.

Tex t :

aList ← bList

Block:

aList bList

Assigns a copy of the list bList to the list aList.

For example, if

bList contains [20, 40, 60],

then

aList will also contain [20, 40, 60] after the

assignment.

Tex t :

aList[i]

Block:

aList

Accesses the element of aList at index i. The rst element

aList is at index 1 and is accessed using the notation

aList[1].

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Instruction Explanation

List Operations (continued)

Tex t :

x ← aList[i]

Block:

x aList i

Assigns the value of aList[i] to the variable x.

Tex t :

aList[i] ← x

Block:

aList

Assigns the value of x to aList[i].

Tex t :

aList[i] ← aList[j]

Block:

aListaList

Assigns the value of aList[j] to aList[i].

Tex t :

INSERT(aList, i, value)

Block:

aList, i, valueINSERT

Any values in aList at indices greater than or equal to i are

shifted one position to the right. The length of the list is increased by

1, and

value is placed at index i in aList.

Tex t :

APPEND(aList, value)

Block:

APPEND

aList, value

The length of aList is increased by 1, and value is placed at

the end of

aList.

Tex t :

REMOVE(aList, i)

Block:

REMOVE aList, i

Removes the item at index i in aList and shifts to the left

any values at indices greater than

i. The length of aList is

decreased by 1.

Tex t :

LENGTH(aList)

Block:

LENGTH

aList

Evaluates to the number of elements in aList.

Tex t :

FOR EACH item IN aList

{

}

Block:

FOR EACH item IN aList

block of statements

The variable item is assigned the value of each element of

aList sequentially, in order, from the rst element to the last

element. The code in

block of statements is executed

once for each assignment of

item.

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Instruction Explanation

Procedures and Procedure Calls

Tex t :

PROCEDURE procName(parameter1,

parameter2, ...)

{

}

Block:

PROCEDURE procName

block of statements

parameter1,

parameter2,...

Denes procName as a procedure that takes zero or more

arguments. The procedure contains

block of statements.

The procedure

procName can be called using the following

notation, where

arg1 is assigned to parameter1, arg2 is

assigned to

parameter2, etc.:

procName(arg1, arg2, ...)

Tex t :

PROCEDURE procName(parameter1,

parameter2, ...)

{

RETURN(expression)

}

Block:

PROCEDURE procName

block of statements

RETURN expression

parameter1,

parameter2,...

Denes procName as a procedure that takes zero or more

arguments. The procedure contains

block of statements

and returns the value of expression. The RETURN

statement may appear at any point inside the procedure and

causes an immediate return from the procedure back to the calling

statement.

The value returned by the procedure

procName can be assigned

to the variable

result using the following notation:

result ← procName(arg1, arg2, ...)

Tex t :

RETURN(expression)

Block:

RETURN

expression

Returns the ow of control to the point where the procedure was

called and returns the value of

expression.

Robot

If the robot attempts to move to a square that is not open or is beyond the edge of the grid, the robot will stay in its current location

and the program will terminate.

Tex t :

MOVE_FORWARD()

Block:

MOVE_FORWARD

The robot moves one square forward in the direction it is facing.

Tex t :

ROTATE_LEFT()

Block:

ROTATE_LEFT

The robot rotates in place 90 degrees counterclockwise (i.e., makes

an in-place left turn).

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Instruction Explanation

Robot

Tex t :

ROTATE_RIGHT()

Block:

ROTATE_RIGHT

The robot rotates in place 90 degrees clockwise (i.e., makes an in-

place right turn).

Tex t :

CAN_MOVE(direction)

Block:

CAN_MOVE direction

Evaluates to true if there is an open square one square in the

direction relative to where the robot is facing; otherwise evaluates to

false. The value of direction can be left, right,

forward, or backward.

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