ProceduralOCR J277
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Procedural · OCR J277 programming practice

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OCR vocabulary

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154 definitions

Accumulator

Iteration

A variable that stores a running total or combined result.

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Algorithmic thinking

Robust programs

Identifying the required steps and the sequence in which they must be completed.

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AND

Selection

A Boolean operator that is true only when both conditions are true.

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Arithmetic operator

Arithmetic

A symbol that tells a program to perform a numerical calculation.

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Array parameter

Procedures & functions

A parameter that receives an array or Python list from the caller.

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ASC()

Strings & arrays

The OCR ERL operation that returns the numeric code of a character.

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Ascending

Iteration

Moving from a smaller value to a larger value.

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Assignment

Procedures & functions

Storing a value, including a returned value, in a variable.

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Authentication

Robust programs

Verifying a user's identity, commonly with a username and password.

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Authorised

Robust programs

Given permission to access a system or resource.

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bool()

Data types & casting

A cast that converts a suitable value into a Boolean.

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Boolean

Selection

A data type with exactly two possible values: true or false.

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Boolean expression

Selection

An expression that evaluates to either true or false.

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Boundary test data

Robust programs

Input at the very edge of an accepted range.

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Brackets

Arithmetic

Symbols used to make part of an expression evaluate before the surrounding operations.

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Branch

Selection

One possible path through a selection statement.

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break

Iteration

A Python statement that immediately leaves the nearest loop.

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Call

Procedures & functions

An instruction that runs a sub-program and supplies any required values.

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case

Selection

One value that may match the switch expression and select its instructions.

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Case conversion

Strings & arrays

Changing letters to uppercase or lowercase without changing the original wording.

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Casting

Data types & casting

Converting one data type into another.

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Character

Data types & casting

A single letter, digit, symbol or space.

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Character code

Strings & arrays

A number used by a computer to represent a character.

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CHR()

Strings & arrays

The OCR ERL operation that returns the character represented by a numeric code.

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Column

Strings & arrays

A vertical group in a table; it can represent one field.

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Combination

Iteration

One pairing of an outer-loop value with an inner-loop value.

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Comparison operator

Selection

An operator such as == or >= that compares two values and produces a Boolean result.

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Concatenation

Strings & arrays

Joining two or more strings using the + operator.

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Condition-controlled loop

Iteration

A loop whose repetition is controlled by a Boolean condition.

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Constant

Variables

A named value that should not change while a program runs.

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Count-controlled loop

Iteration

A loop that repeats a known number of times.

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Counter

Iteration

A variable updated to record how many times an event has occurred.

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Data structure

Strings & arrays

A method of organising and storing data so it can be accessed and used.

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Data type

Data types & casting

A classification that controls what data can be stored and which operations can be used.

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Debugging

Robust programs

Finding, understanding and correcting errors in a program.

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Decomposition

Robust programs

Breaking a problem into smaller manageable parts that can be solved individually.

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default

Selection

The fallback branch used when no case value matches.

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Defensive design

Robust programs

Designing a program to handle misuse and unexpected input safely.

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Descending

Iteration

Moving from a larger value to a smaller value.

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DIV

Arithmetic

Integer division that returns the whole-number quotient and discards the remainder.

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do-until loop

Iteration

A post-test loop that repeats until its condition becomes true.

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Element

Strings & arrays

One value stored in an array.

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else

Selection

The fallback branch used when no earlier condition was true.

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elseif / elif

Selection

A later condition checked only when all earlier branches were false.

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End of file

Robust programs

The position after the final item in a file.

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endswitch

Selection

The OCR ERL keyword that closes a switch structure.

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Erroneous test data

Robust programs

Input of the wrong data type.

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Exponentiation

Arithmetic

Raising one number to the power of another.

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Expression

Arithmetic

Values, variables and operators combined to produce a result.

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Field

Strings & arrays

One category of data within a record.

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File

Robust programs

A named collection of data stored outside the program's variables.

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File handle

Robust programs

The program value used to access an open file.

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Final testing

Robust programs

Testing the complete program at the end of development before release.

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float() / real()

Data types & casting

Casts that convert a suitable value into a decimal number.

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Format check

Robust programs

A validation check that ensures data follows a required pattern or structure.

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Function

Procedures & functions

A sub-program that returns a value.

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Global variable

Procedures & functions

A variable declared outside sub-programs and accessible throughout the program.

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Identifier

Variables

The exact name given to a variable, constant or subroutine.

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if

Selection

The first condition in an if selection structure.

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Inclusive

Robust programs

Including the boundary values themselves.

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Inclusive range

Robust programs

A range that can produce both its minimum and maximum values.

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Increment

Iteration

Increase a stored number and save the new value.

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Index

Procedures & functions

A zero-based position used to access an array element.

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Infinite loop

Iteration

A loop that never reaches a false stopping condition.

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Initialise

Iteration

Give a variable its starting value before it is first used.

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Inner condition

Selection

A condition evaluated only after its enclosing branch is entered.

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Inner loop

Iteration

The enclosed loop that completes for each outer-loop iteration.

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Input

Input

Data received by a program, for example from a user, file or sensor.

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Input sanitisation

Robust programs

Removing invalid or dangerous characters from input before it is processed.

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int()

Data types & casting

A cast that converts a suitable value into an integer.

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Integer

Data types & casting

A whole number with no decimal point.

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Invalid test data

Robust programs

Input of the correct type that lies outside the permitted rules or range.

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Iteration

Iteration

Repeating a set of instructions.

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Iterative testing

Robust programs

Testing modules during development so faults can be corrected as the program is built.

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Length

Strings & arrays

The number of characters contained in a string.

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Length check

Robust programs

A validation check that ensures input has the required number of characters.

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Lifetime

Procedures & functions

The time for which a variable exists in memory.

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Linear search

Strings & arrays

Checking array values one by one in order until a target is found or the list ends.

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Literal

Output

A value written directly into the code.

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Local variable

Procedures & functions

A variable created inside a sub-program and accessible only there.

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Logic error

Robust programs

An error where the program runs but produces incorrect or unexpected output.

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Look-up check

Robust programs

A validation check that compares input with a predefined list of allowed values.

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Loop counter

Strings & arrays

The changing for-loop variable that can be used as an array index.

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Loop variable

Iteration

A variable whose value changes automatically for each pass through a for loop.

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Main program

Robust programs

The controlling part that gathers data and calls the required sub-programs.

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Maintainability

Robust programs

How easy a program is to understand, update and fix after it has been written.

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MOD

Arithmetic

An operation that returns the remainder after division.

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Mutable

Procedures & functions

Able to be changed after creation; Python lists are mutable.

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Nested loop

Iteration

A loop placed inside another loop.

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Nested selection

Selection

A selection statement placed inside another selection statement.

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Normal test data

Robust programs

Typical valid input that should be accepted and processed correctly.

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NOT

Selection

A Boolean operator that reverses true and false.

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Off-by-one error

Strings & arrays

Starting or ending a traversal one index too early or too late.

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One-dimensional array

Strings & arrays

A fixed-size linear collection of values of one data type under one name.

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Open

Robust programs

Prepare a file for reading or writing and obtain a file handle.

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Operand

Arithmetic

A value or variable that an operator acts on.

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Operator precedence

Selection

The order in which operators in a combined expression are evaluated.

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OR

Selection

A Boolean operator that is true when either condition, or both conditions, are true.

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ord() / chr()

Strings & arrays

The Python functions corresponding to OCR ASC() and CHR().

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Outer condition

Selection

The first condition that controls whether an inner selection is reached.

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Outer loop

Iteration

The enclosing loop that starts a new complete run of the inner loop.

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Output

Output

Data or information a program displays to the user.

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Parameter

Procedures & functions

A named value received by a sub-program when it is called.

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Parameter list

Procedures & functions

The parameter names written inside the brackets of a sub-program definition.

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Post-test

Iteration

Checking a stopping condition after the loop body has executed.

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Pre-test

Iteration

Checking a condition before executing the loop body.

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Precedence

Arithmetic

Rules that decide which operator in an expression is evaluated first.

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Presence check

Robust programs

A validation check that ensures data has been entered and is not blank.

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Procedural solution

Robust programs

A complete program organised as ordered instructions and reusable sub-programs.

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Procedure

Procedures & functions

A sub-program that performs a task without returning a value.

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Prompt

Input

The message that tells a user what to enter.

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Pseudo-random

Robust programs

Generated by an algorithm to behave like random data.

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Quotient

Arithmetic

The result of division; with DIV, only the whole-number part is returned.

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Random number

Robust programs

A value selected unpredictably from a specified range.

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Range check

Robust programs

A check that a value lies between permitted lower and upper limits.

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range()

Iteration

A Python function that produces the values used by a for loop; its stop value is excluded.

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Re-prompt

Robust programs

Ask for input again after an invalid value.

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Real

Data types & casting

A numeric value that can include a decimal part.

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Record

Strings & arrays

A group of related field values describing one entity.

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Refinement

Robust programs

Improving an algorithm after design and testing so it is more correct, readable, efficient or useful.

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Remainder

Arithmetic

The amount left after making as many complete groups as possible.

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Return

Procedures & functions

Send a value from a function back to the instruction that called it.

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Return array

Procedures & functions

Send a complete processed array back from a function.

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Return value

Input

The value produced by an instruction such as input().

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Returned value

Procedures & functions

The result supplied by a completed function call.

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Reuse

Procedures & functions

Calling the same sub-program with different values instead of copying its code.

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Row

Strings & arrays

A horizontal group in a table; it can represent one record.

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Runtime error

Robust programs

An error that stops a program after execution has begun.

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Scope

Procedures & functions

The part of a program in which a variable can be accessed.

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Seed

Robust programs

A starting value that makes a pseudo-random sequence repeatable for testing.

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Selection

Selection

Using a condition to decide which path through a program is executed.

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Sentinel value

Iteration

A special input value used to signal that repetition should stop.

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Separator

Input

A character or space placed between items of output.

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Sequence

Arithmetic

Instructions executed in order, one after another, from top to bottom.

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Slice

Strings & arrays

Python syntax that extracts values from a start index up to, but not including, an end index.

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Step

Iteration

The amount added to the loop variable after each iteration.

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str()

Data types & casting

A cast that converts a value into a string.

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String

Data types & casting

A sequence of characters used for names, text, identifiers and phone numbers.

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String manipulation

Strings & arrays

Performing operations on strings, such as joining, measuring or changing case.

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Sub-program

Procedures & functions

A named, reusable block of code that performs a specific task.

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Subroutine

Procedures & functions

Another name for a sub-program, such as a procedure or function.

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Substring

Strings & arrays

A consecutive section extracted from a larger string.

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switch

Selection

A selection structure that checks one expression against several possible values.

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Syntax

Output

The rules that say how code must be written.

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Syntax error

Robust programs

An error that breaks language grammar and prevents the program from running or being translated.

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Test plan

Robust programs

A record of test data, test type, expected result and actual result.

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Traversal

Strings & arrays

Visiting each item in a data structure in a systematic order.

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Two-dimensional array

Strings & arrays

An array of arrays arranged like a table with rows and columns.

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Type check

Robust programs

A validation check that ensures data has the required data type.

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Update

Variables

Assigning a new value to a variable that already exists.

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Validation

Robust programs

Checking that input is reasonable and follows required rules before processing it.

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Variable

Variables

A named location in memory that stores a value which can change.

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while loop

Iteration

A pre-test loop that repeats while its condition is true.

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Zero-indexed

Strings & arrays

Numbered so the first character or item has index 0.

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