Data Structures in C - Multi-dimensional Arrays, Structs, and Unions

This set of vocabulary flashcards covers advanced C data structures including memory reallocation, multi-dimensional array management, structs, unions, and custom vector implementation.

realloc

A function with the signature $void* realloc(void* old_ptr, unsigned int size)$ that allocates new memory on the heap, copies data from the old pointer to the new memory, and then frees the old pointer; if $old_ptr$ is null, it behaves like malloc.

struct

A mechanism for packing multiple variables of different types into a single fixed-size block known at compile time, treating them as a single data structure rather than an object. Can use sizeof(struct MyStruct) to determine byte size.

Dot syntax

The syntax used to access member variables within a C struct instance, for example, $x.a = 5$.

Arrow syntax

A shortcut in C that is equivalent to dereferencing a pointer and accessing a member variable of a struct at the same time.

Words

Blocks of bytes that processors use to access memory; structs are often padded to align with this system word size for efficiency.

pragma pack(n)

A compiler directive used to change the alignment of data by adjusting the padding of internal struct members to $n$-byte boundaries.

Union

A data container that can store a single item of one or more possible types, with its total size determined by the size of its largest member.

typedef

A keyword that allows the creation of an alias for custom types, often used to refer to structs without the prefix keyword 'struct'.