Dynamic Array WS14

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

#ifndef TYPE
#define TYPE double
#endif

struct dynArr {
    TYPE *data;     /* pointer to the data array */
    int size;       /* number of elements in the array */
    int capacity;   /* capacity of the data array */
};

void dynArrayInit(struct dynArr *v, int capacity) {
    v->data = (TYPE *) malloc(sizeof(TYPE) * capacity);
    assert(v->data != 0);
    v->size = 0;
    v->capacity = capacity;
}

void dynArrayFree(struct dynArr *v) {
    if(v->data != 0) {
        free(v->data);  /* free memory space */
        v->data = 0;    /* make it point to NULL */
    }
    v->size = 0;
    v->capacity = 0;
}

int dynArraySize(struct dynArr *v) {
    return v->size;
}

void _dynArraySetCapacity(struct dynArr *v, int newCapacity) {
    assert(newCapacity > 0);

    printf("⚙️ Resizing array: old capacity = %d, new capacity = %d\n",
           v->capacity, newCapacity);

    if (newCapacity < v->size) {
        v->size = newCapacity; /* 截断已有元素，防止越界 */
    }
    TYPE *newData = (TYPE *) malloc(sizeof(TYPE) * newCapacity);
    assert(newData != 0);

    for (int i = 0; i < v->size; ++i) {
        newData[i] = v->data[i];
    }

    free(v->data);
    v->data = newData;
    v->capacity = newCapacity;
}

void dynArrayAdd(struct dynArr *v, TYPE val) {
    /* Check if a resize is necessary */
    if(v->size >= v->capacity)
        _dynArraySetCapacity(v, 2 * v->capacity);
    v->data[v->size] = val;
    v->size++;
}

/* ---------- 演示用 main 函数 ---------- */
int main() {
    struct dynArr arr;
    dynArrayInit(&arr, 2);  // 初始容量设为 2
    printf("Initial capacity: %d\n", arr.capacity);

    // 连续插入多个元素，触发扩容
    for (int i = 0; i < 10; i++) {
        dynArrayAdd(&arr, i * 1.1);  // 插入 i*1.1
        printf("Added %.1f | size = %d, capacity = %d\n",
               arr.data[arr.size-1], arr.size, arr.capacity);
    }

    // 打印数组内容
    printf("Final array: [");
    for (int i = 0; i < arr.size; i++) {
        printf("%.1f", arr.data[i]);
        if (i < arr.size-1) printf(", ");
    }
    printf("]\n");

    dynArrayFree(&arr);
    return 0;
}

Output

Initial capacity: 2
Added 0.0 | size = 1, capacity = 2
Added 1.1 | size = 2, capacity = 2
⚙️ Resizing array: old capacity = 2, new capacity = 4
Added 2.2 | size = 3, capacity = 4
Added 3.3 | size = 4, capacity = 4
⚙️ Resizing array: old capacity = 4, new capacity = 8
Added 4.4 | size = 5, capacity = 8
Added 5.5 | size = 6, capacity = 8
Added 6.6 | size = 7, capacity = 8
Added 7.7 | size = 8, capacity = 8
⚙️ Resizing array: old capacity = 8, new capacity = 16
Added 8.8 | size = 9, capacity = 16
Added 9.9 | size = 10, capacity = 16
Final array: [0.0, 1.1, 2.2, 3.3, 4.4, 5.5, 6.6, 7.7, 8.8, 9.9]

=== Code Execution Successful ===

Note

In C, the compiler cannot identify whether the result would exceed maximum memory location of the array. Thus we need the dynamic array