Karnataka KSEAB SSLC JTS Programming in ANSI C flashcards

34 cards. Read the term and the definition here. The deck at the top of this page is optional.

Token

The smallest meaningful unit of a C program. The six classes are keywords, identifiers, constants, string literals, operators, and separators such as semicolons and braces.

Identifier rules

A name must start with a letter or underscore and contain only letters, digits, or underscores. It is case-sensitive and cannot be a keyword.

sizeof operator

A compile-time unary operator that returns the size of a type or object in bytes as type size_t. It does not evaluate its operand when applied to a type.

const qualifier

Marks an object as read-only after initialization. Attempting to modify it through that name is a compile-time error; it is not a compile-time constant for array sizes in C89.

Integer division truncation

When both operands of / are integers, the fractional part is discarded and the result truncates toward zero. The % operator gives the remainder with the dividend's sign.

Short-circuit evaluation

The && and || operators evaluate the left operand first and skip the right operand when the result is already known. This is used to guard null-pointer checks.

Left shift operator

The expression a << n shifts the bits of a left by n positions, filling with zeros. For non-negative values it multiplies by 2 to the power n.

Cast expression

A cast such as (float) a converts a value to the named type explicitly. It is used to force floating-point division or to narrow a value deliberately.

switch fall-through

When a case has no break statement, execution continues into the next case. Fall-through is sometimes intentional for grouping labels but is a common bug source.

do-while loop

A loop that executes its body once before testing the condition, so the body always runs at least once. A semicolon follows the closing while condition.

break versus continue

break exits the innermost loop or switch immediately. continue skips the rest of the current iteration and proceeds to the next condition test or loop update.

for loop execution order

The initialization runs once, the condition is tested before each iteration, the body executes, and the update expression runs after each iteration before the next test.

Function prototype

A declaration that gives a function's return type, name, and parameter types, letting the compiler check argument counts and types at each call site before the definition.

Pass by value

C passes arguments by copying their values into parameters. To let a function modify a caller's variable, pass its address and dereference the pointer inside the function.

Static local variable

A variable declared static inside a function keeps its value between calls. It is initialized only once, before the first call, and has program lifetime.

Recursion base case

The condition that stops a recursive function from calling itself again. Every recursive function needs at least one base case, or it recurses until the stack overflows.

Array index range

An array of n elements is valid at indices 0 through n-1. C does not check bounds, so an out-of-range index is undefined behavior, not a compile error.

String terminator

Every C string is a char array ending in the null character '\0'. String functions locate the end by scanning for this terminator, which is not counted in strlen.

strcmp return value

Compares two strings character by character and returns a negative value, zero, or a positive value as the first string is less than, equal to, or greater than the second.

Row-major storage

A two-dimensional array is stored row by row: all elements of row 0 come first, then row 1, and so on. The last index varies fastest in memory.

Pointer declaration

The form int *p; declares p as a pointer to int. The asterisk binds to the variable name, so int *a, b; declares one pointer and one int.

Pointer arithmetic unit

Adding 1 to a pointer advances it by the size of the pointed-to type in bytes. Subtracting two pointers into the same array yields the number of elements between them.

malloc and free

malloc(size) returns a pointer to uninitialized heap memory or NULL on failure. free releases the block; every successful allocation needs exactly one matching free.

Arrow operator

For a pointer to a structure, p->member accesses the member. It is shorthand for (*p).member and is used with pointers to structs passed to functions.

Union storage

A union lets several members share the same memory area. Its size is at least that of its largest member, and only one member holds a valid value at a time.

typedef purpose

typedef creates a new name (alias) for an existing type, such as typedef struct Node Node;. It does not create a new type, only a convenient synonym.

Enum constants

An enumeration declares named integer constants. The first is 0 by default, and each following one is one greater unless an explicit value is given.

scanf return value

scanf returns the number of input items successfully assigned, or EOF if input ends before any conversion. Checking this value detects malformed input.

fopen modes

Text modes are r (read), w (write, truncates), and a (append). Adding + allows both reading and writing; adding b opens the file in binary mode.

fgets versus scanf

fgets(buf, size, stdin) reads at most size-1 characters including spaces and stops at a newline, making it safer than scanf with %s for line input.

Object-like macro

A #define without parameters, such as #define MAX 100. The preprocessor replaces every later occurrence of the name with the token sequence before compilation begins.

Include guard

A pattern using #ifndef, #define, and #endif around a header's contents so that including the same header twice does not cause duplicate definitions.

Compilation stages

Preprocessing expands directives, compilation produces assembly, assembly produces object code, and linking combines object files with library code into an executable.

Flowchart decision symbol

A diamond shape represents a decision with one input and two labeled outputs, typically yes and no. Loops are drawn with an arrow returning to an earlier step.