BCSE (Class X) key terms

A finite, ordered set of unambiguous steps that transforms given inputs into a desired output. Every step must be precise enough to be carried out mechanically, and the process must terminate.

A diagram that represents an algorithm using standard symbols connected by arrows, such as ovals for start and end, rectangles for processes, and diamonds for decisions. It shows the order in which steps run.

A structured, English-like notation for writing algorithms that borrows keywords from programming languages but ignores strict syntax rules. It lets a designer plan logic before committing to a particular language.

A named storage location whose value can change while a program runs. Each variable has an identifier, a data type, and a current value held in memory until it is reassigned or the program ends.

A named value fixed at the time it is declared and not allowed to change during execution. Constants make programs easier to read and prevent accidental modification of important fixed values.

A classification that specifies which kind of values a variable may hold and which operations are valid on them. Common types include integer, real, character, string, and Boolean.

A whole number with no fractional part, such as 7, -3, or 0. Integer variables are used for counting and indexing, and arithmetic on them produces exact results within the type's range.

A numeric value that may contain a fractional part, such as 3.75 or -0.5. Real values are stored approximately in most computers, so comparisons for exact equality should be avoided.

A data type with exactly two possible values, usually written true and false. Boolean expressions form the conditions that control decisions and loops in programs and logic circuits.

A statement that stores a value into a variable, replacing whatever was held there before. The right-hand side is evaluated first, then the result is placed in the named location on the left.

A combination of values, variables, operators, and function calls that is evaluated to produce a single result. Expressions appear on the right of assignments and inside conditions and output statements.

The agreed order in which operators in an expression are applied, for example multiplication before addition. Parentheses override the default order and clarify the intended grouping of operations.

A symbol that performs a mathematical operation on numeric values, such as plus, minus, star for multiplication, slash for division, and MOD for remainder. These follow standard precedence rules.

Division of two whole numbers in which any fractional part of the result is discarded, leaving only the whole-number quotient. The related MOD operation gives the remainder instead.

An operation, often written MOD, that returns the remainder after one integer is divided by another. It is widely used to test divisibility and to wrap values around a fixed range.

An operator such as AND, OR, or NOT that combines or negates Boolean conditions. AND is true only when both parts are true; OR needs one true part; NOT reverses a single value.

A table listing every possible combination of input truth values for a logical expression alongside the resulting output. It is used to verify logic and to design digital circuits.

A Boolean expression that a program tests to choose between alternative paths. If the condition evaluates to true one block runs; otherwise another block, or none, is executed.

A control structure that chooses which statements to execute based on a condition, using forms such as if, if-else, and case. Only the branch matching the tested condition runs.

A control structure that repeats a block of statements while a condition holds or for a fixed number of times. Loops must eventually stop, so the controlling condition must change.

A programming construct that repeats instructions, typically either a counted loop with a known number of passes or a conditional loop that continues while a test remains true.

A loop whose terminating condition never becomes false, so execution never leaves the loop. It usually results from a missing or incorrect update to the variable controlling the condition.

A collection of elements of the same data type stored under one name and accessed by an index. Indexing normally starts at zero or one, and each element occupies a numbered position.

A number or key used to locate a particular element within an array or string. Valid indexes lie between the lower and upper bounds of the structure, and out-of-range use causes an error.

A sequence of characters treated as a single value, such as a name or a sentence. Strings support operations like finding length, joining, extracting substrings, and comparing.

A single letter, digit, punctuation mark, or symbol stored as one unit. Characters are usually encoded numerically, which is why comparisons and conversions between characters and codes are possible.

A standard character-encoding scheme that assigns a numeric code from 0 to 127 to letters, digits, punctuation, and control characters. It underlies many text representations and comparison rules.

A universal character-encoding standard that assigns a unique code point to characters from most of the world's writing systems. It extends far beyond the limited range of older encodings such as ASCII.

A named block of statements that performs a task and may accept parameters and return a value. Functions let programmers reuse logic and break large problems into smaller, testable parts.

A named block of statements that performs an action but does not return a value. Like a function it may take parameters, and calling it runs its statements in order.

A named input declared by a function or procedure that receives a value when the routine is called. Parameters let the same code work on different data each time.

The actual value or variable supplied when a function or procedure is called. It is matched to the corresponding parameter so the routine can use it during execution.

The result a function sends back to the point where it was called. It must match the declared return type, and the calling code can store or use it in further expressions.

A mistake that breaks the grammar rules of a programming language, such as a missing bracket or misspelled keyword. Such errors are normally detected before or during translation.

A flaw in a program's reasoning that lets it run without crashing but produce incorrect results. Logic errors are the hardest to find because no error message is generated.

A fault that occurs while a program is executing, such as dividing by zero or accessing an invalid array index. It usually halts the program or raises an exception.

The process of locating, understanding, and correcting errors in a program. It typically involves reading code, tracing variable values, and testing with carefully chosen inputs.

A translator that converts a whole program written in a high-level language into machine code before it runs. It reports syntax errors for the entire source file at translation time.

A translator that reads and executes a program one statement at a time without producing a separate machine-code file. It stops at the first error it meets during execution.

The binary instruction set that a processor executes directly, made up of operation codes and operands. High-level source code must be translated into this form before the hardware can run it.