Initialization

Tags: #◇CCPROG2 #◇C Programming #◇Programming #◇Computer Science #◇Data Structures #◇Data Types #◇Structured Programming #◇Memory Management

◇Overview

Array initialization assigns values to array elements at the time of declaration.

◇Key Concepts

Initializer list syntax: {val1, val2, ...} Partial initialization fills remaining elements with 0 Size can be omitted if initializer is provided Uninitialized local arrays contain garbage values

◇Details / Theory

Full Initialization

『』

int arr[5] = {10, 20, 30, 40, 50};  // All 5 elements set

Partial Initialization

『』

int arr[5] = {1, 2};  // arr = {1, 2, 0, 0, 0}

Remaining elements are automatically initialized to 0 (for numeric types) or '\0' (for char).

Size Omission

『』

int arr[] = {10, 20, 30};  // Compiler infers size = 3
char str[] = "Hello";       // Size = 6 (includes '\0')

Zero Initialization

『』

int arr[100] = {0};  // All 100 elements set to 0

String Initialization

『』

char greeting[6] = {'H', 'e', 'l', 'l', 'o', '\0'};
char greeting[] = "Hello";  // Equivalent, compiler adds '\0'

2D Array Initialization

『』

int matrix[2][3] = {
    {1, 2, 3},
    {4, 5, 6}
};

◇Common Pitfalls

Assuming uninitialized local arrays are zeroed — they contain garbage values. Forgetting the null terminator when initializing char arrays as strings. Providing more initializers than the array size — compilation error.

◇Summary

TL;DR — Arrays can be initialized at declaration using {...}. Partial initialization zeros remaining elements. Uninitialized local arrays contain garbage. String arrays need '\0' termination.

◇Links

Related: ◇Declaration — ◇Accessing Elements — ◇Size — ◇Element Type — ◇One-Dimensional Arrays (1D Arrays) Source / Reference:

Previous Topic: ◇Memory Allocation
Next Topic: ◇Accessing Elements
Related Notes: ◇Declaration, ◇Accessing Elements

INITIALIZATION