C语言数组一种巧妙的使用方式

时间：2022-05-13 19:04:31

　　作为计算机一种比较古老的语言,它并没有随着岁月老去,而是仍旧在整个领域发挥出耀眼的光芒,就像写作,有很多光芒万丈的句子值得我们去珍藏,今天就遇到了个比较巧妙的数组使用方法,做个记录,以供后续使用.

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

typedef unsigned long long ULL;

#define BUFFER_SIZE ((int)(0x80 * sizeof(void*) * sizeof(ULL)))

#define sb_free(a)          ((a) ? free(stb__sbraw(a)), 0 : 0)

#define sb_push(a, v)       (stb__sbmaybegrow(a, 1), (a)[stb__sbn(a)++] = (v))

#define sb_count(a)         ((a) ? stb__sbn(a) : 0)

#define sb_add(a, n)        (stb__sbmaybegrow(a,n), stb__sbn(a)+=(n), &(a)[stb__sbn(a) - (n)])

#define sb_last(a)          ((a)[stb__sbn(a) - 1])

#define stb__sbraw(a) ((int *) (a) - 2)

#define stb__sbm(a)   stb__sbraw(a)[0]

#define stb__sbn(a)   stb__sbraw(a)[1]

#define stb__sbneedgrow(a, n)  ((a) == 0 || stb__sbn(a) + (n) >= stb__sbm(a))

#define stb__sbmaybegrow(a, n) (stb__sbneedgrow(a, (n)) ? stb__sbgrow(a, n) : 0)

#define stb__sbgrow(a, n)      ((a) = stb__sbgrowf((a), (n), sizeof(*(a))))

static void * stb__sbgrowf(void *arr, int increment, int itemsize) {

 int dbl_cur = arr ? 2 * stb__sbm(arr) : 0;

 int min_needed = sb_count(arr) + increment;

 int m = dbl_cur > min_needed ? dbl_cur : min_needed;

 int *p = (int *) realloc(arr ? stb__sbraw(arr) : 0, itemsize * m + sizeof(int) * 2);

 if (p) {

    if (!arr)

       p[1] = 0;

    p[0] = m;

    return p + 2;

 } else {

    return (void *) (2  *sizeof(int));

 }

}

int main (int argc, char **argv) {

    ULL nr = 0; char *buf = NULL;

    int cnt = 0;

    FILE *fd = fopen (argv[1], "rb");

    do {

        char *str = calloc(BUFFER_SIZE, sizeof(char));

        nr = fread(str, sizeof(char), BUFFER_SIZE, fd);

        int n = feof (fd);

        printf(" nr:%d n:%d \n\r",nr,n);

        while (*str) sb_push(buf, *str++);

        //free(str - nr);

    } while (!feof (fd));

    printf("%s\n", buf);

    sb_free(buf);

    return 0;

}

　　参考:

1 https://pastebin.com/FzYPtZ9j

2 https://github.com/nothings/stb/blob/master/stretchy_buffer.h

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