Arrays & Strings

#include <stdio.h>
#include <string.h>

int main() {
    // Array declaration and initialization
    int numbers[5] = {10, 20, 30, 40, 50};
    int zeros[100] = {0};  // All elements initialized to 0

    // Array access
    printf("First: %d, Last: %d\n", numbers[0], numbers[4]);
    // No bounds checking! numbers[10] compiles but crashes/corrupts

    // Array iteration
    int size = sizeof(numbers) / sizeof(numbers[0]); // 5
    for (int i = 0; i < size; i++) {
        printf("%d ", numbers[i]);
    }

    // 2D array
    int matrix[3][3] = {
        {1, 2, 3},
        {4, 5, 6},
        {7, 8, 9}
    };

    // Strings (null-terminated char arrays)
    char greeting[] = "Hello";  // Auto-sized: 6 chars (5 + null \0)
    char name[50];              // Buffer for up to 49 chars + null

    // String functions (string.h)
    printf("Length: %zu\n", strlen(greeting));     // 5
    strcpy(name, "Alice");                         // Copy
    strcat(name, " Smith");                        // Concatenate
    printf("Name: %s\n", name);                    // "Alice Smith"

    // Safe alternatives (prevent buffer overflow)
    strncpy(name, "Bob", sizeof(name) - 1);
    name[sizeof(name) - 1] = '\0';  // Ensure null termination

    // String comparison
    if (strcmp(greeting, "Hello") == 0) {
        printf("Strings are equal\n");
    }
    // strcmp returns: 0 (equal), <0 (first < second), >0 (first > second)

    // Character operations
    char ch = 'A';
    printf("Lowercase: %c\n", ch + 32);  // 'a' (ASCII math)

    return 0;
}