C中具有负索引的数组的Calloc
我有一个负索引数组。它是一个具有真实维度[dim_y+40][dim_x+40]的数组，但用户使用该数组时将其视为具有维度[dim_y][dim_x]。 首先我有全局的，并且已经定义了维dim_x，dim_y，所以我有这个C中具有负索引的数组的Calloc,c,arrays,global,declare,calloc,C,Arrays,Global,Declare,Calloc,我有一个负索引数组。它是一个具有真实维度[dim_y+40][dim_x+40]的数组，但用户使用该数组时将其视为具有维度[dim_y][dim_x]。 首先我有全局的，并且已经定义了维dim_x，dim_y，所以我有这个 int map_boundaries[dim_y + 40][dim_x + 40]; int (*map)[dim_x+40] = (int(*)[dim_x+40])&map_boundaries[20][20]; 它工作得很好。 现在我需要维度dim_y和di
int map_boundaries[dim_y + 40][dim_x + 40];
int (*map)[dim_x+40] = (int(*)[dim_x+40])&map_boundaries[20][20];
int **map_boundaries;
main（）中使用calloc
map_bounders=（int**）calloc（dim_y+40，sizeof（int*）；
对于（i=0；i
，但我不知道如何申报第二行
为了更好地理解边界，我在这里的第二条评论中写道：我将分配一个数组：
int* storage = calloc((dim_x + 40) * (dim_y + 40), sizeof(int));
然后，我将以不透明结构将其返回给用户，如下所示：
struct map {
int* storage;
size_t dim_x;
size_t dim_y;
};
然后我将为用户定义一个索引函数：
int* get_cell(struct map* m, x, y) {
return &m->storage[(x + 20) + (m->dim_x + 40) * (y + 20)];
}
如果用户希望在一行中读取/写入多个元素，则可能需要获取整行：
int* get_row(struct map* m, y) {
return get_cell(m, 0, y);
}
size_t get_row_size(struct map* m) {
return m->dim_x;
}
由于您希望在运行时确定维度，因此在任何情况下都需要进行运行时索引计算。这是我的代码版本。int**map
值是用户和库用来访问数据的值。矩阵
结构封装了有关数组的所有信息，包括用于初始化映射
的成员。代码设置大小，分配和初始化结构，然后初始化数组，然后像用户和库一样使用它。最后，释放分配的内存
实际上，您可能希望将其拆分为多个单独的函数
来源：2da.c
：
“仍然可到达”块是stdout
的缓冲区；如果我包括fclose（stdout）在从main（）
返回之前，它将运行。Mac OS X运行时库也分配了大量内存，但这种使用情况在隐藏的信息中进行了标识
评论和回应
我进行了整个初始化，如您在两行中看到的。但问题不在于初始化；问题是，在每一帧中，map的值都会发生变化。所以我只需要一张直接指向“边界地图”的“地图”<代码>地图[0][0]
是边界(地图[20][20]
等等。我试图声明global**map
，然后将第二行写入main，但在cast方面出现了一个错误<代码>（*地图）[dim_x+40]**地图malloc（）malloc（）。这可以传递给函数，就像传递基于堆栈的VLA一样。该代码在Mac OS X 10.9.5上的GCC 4.9.1下干净地编译：
$ gcc -g -O3 -std=c99 -Wall -Wextra -Wmissing-prototypes -Wstrict-prototypes -Werror \
> 2dv.c -o 2dv
根据要求，它运行干净，无泄漏
来源：2dv.c
：
我想你的意思是，你需要每个顶级维度“需要变量”。例如，map\u-bounders[0]
将指向一个数组，该数组的维数可能与map\u-bounders[1]
等数组的维数不同。如果这不是你的意思，也许可以澄清你的问题（并包括你的calloc
行，你似乎没有特别的原因而遗漏了该行）。@WhozCraig抱歉，我需要这个dim\y，dim_x是可变的是的，我们知道了。同样，您的意思是dim_x
需要能够每行改变吗？这很重要。现在，您使用的是VLA声明，它适用于任何给定的dim_x
和dim_y
，这些声明将适合您的自动变量允许空间，但如果您希望，例如，第一行包含3个元素，第二行包含5个元素，则无法工作。这就是您需要的吗？@WhozCraig no，我只需要从用户那里得到两个值，一个dim_x和一个dim_y，就像我有一个普通的双数组一样，例如dim_y=10，dim_x=15。因此，每一行都有相同数量的列SC99支持VLA，因此从用户处获取它们后，可以使用旧方式声明它们。它被称为可变长度数组。谢谢你的回答，但我的模拟器已经大量使用了gpu，我做了整个初始化，如你在2行中看到的。但问题不是初始化，问题是在每一帧中map的值都会改变。所以我只需要一张直接指向“边界地图”的“地图”。地图[0][0]是边界图[20][20]等等。我试图声明全局**映射，然后将第二行写入main，但在cast方面出现错误。这是一张**地图，不是吗？
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include "stderr.h"
typedef struct Matrix
{
int *map_base;
int **map_rows;
int x_dim;
int y_dim;
int extra;
int **map;
} Matrix;
int main(void)
{
Matrix m;
int x_dim = 8;
int y_dim = 6;
int extra = 5;
/* Allocation */
m.extra = extra;
m.x_dim = x_dim;
m.y_dim = y_dim;
int x_cells = x_dim + 2 * extra;
int y_cells = y_dim + 2 * extra;
m.map_base = calloc(x_cells * y_cells, sizeof(**m.map));
if (m.map_base == 0)
err_syserr("Failed to allocate %zu bytes memory\n",
x_cells * y_cells * sizeof(**m.map));
m.map_rows = calloc(x_cells, sizeof(*m.map));
if (m.map_rows == 0)
err_syserr("Failed to allocate %zu bytes memory\n",
x_cells * sizeof(*m.map));
//printf("Map base: 0x%.8" PRIXPTR "\n", (uintptr_t)m.map_base);
//printf("Map rows: 0x%.8" PRIXPTR "\n", (uintptr_t)m.map_rows);
for (int i = 0; i < x_cells; i++)
{
m.map_rows[i] = &m.map_base[i * y_cells + extra];
//printf("Row[%2d] 0x%.8" PRIXPTR "\n", i, (uintptr_t)m.map_rows[i]);
}
m.map = &m.map_rows[extra];
int **map = m.map;
//printf("Map: 0x%.8" PRIXPTR "\n", (uintptr_t)map);
/* Initialization */
int x_min = -extra;
int y_min = -extra;
int x_max = x_dim + extra;
int y_max = y_dim + extra;
printf("Initialization:\n");
for (int i = x_min; i < x_max; i++)
{
for (int j = y_min; j < y_max; j++)
{
map[i][j] = i * 100 + j;
//printf("[%2d,%2d] = %4d\n", i, j, map[i][j]);
}
}
printf("User view:\n");
for (int i = 0; i < x_dim; i++)
{
for (int j = 0; j < y_dim; j++)
printf("[%2d,%2d] = %4d\n", i, j, map[i][j]);
}
printf("Library view:\n");
for (int i = x_min; i < x_max; i++)
{
for (int j = y_min; j < y_max; j++)
printf("[%2d,%2d] = %4d\n", i, j, map[i][j]);
}
/* Deallocation */
free(m.map_base);
free(m.map_rows);
return 0;
}
$ gcc -O3 -g -I/Users/jleffler/inc -std=c11 -Wall -Wextra -Wmissing-prototypes \
> -Wstrict-prototypes -Wold-style-definition -Werror 2da.c -o 2da \
> -L/Users/jleffler/lib/64 -ljl
$ valgrind ./2da
==26293== Memcheck, a memory error detector
==26293== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==26293== Using Valgrind-3.10.0.SVN and LibVEX; rerun with -h for copyright info
==26293== Command: 2da
==26293==
Initialization:
User view:
[ 0, 0] = 0
[ 0, 1] = 1
[ 0, 2] = 2
[ 0, 3] = 3
[ 0, 4] = 4
[ 0, 5] = 5
[ 1, 0] = 100
[ 1, 1] = 101
[ 1, 2] = 102
[ 1, 3] = 103
[ 1, 4] = 104
[ 1, 5] = 105
[ 2, 0] = 200
[ 2, 1] = 201
[ 2, 2] = 202
[ 2, 3] = 203
[ 2, 4] = 204
[ 2, 5] = 205
[ 3, 0] = 300
[ 3, 1] = 301
[ 3, 2] = 302
[ 3, 3] = 303
[ 3, 4] = 304
[ 3, 5] = 305
[ 4, 0] = 400
[ 4, 1] = 401
[ 4, 2] = 402
[ 4, 3] = 403
[ 4, 4] = 404
[ 4, 5] = 405
[ 5, 0] = 500
[ 5, 1] = 501
[ 5, 2] = 502
[ 5, 3] = 503
[ 5, 4] = 504
[ 5, 5] = 505
[ 6, 0] = 600
[ 6, 1] = 601
[ 6, 2] = 602
[ 6, 3] = 603
[ 6, 4] = 604
[ 6, 5] = 605
[ 7, 0] = 700
[ 7, 1] = 701
[ 7, 2] = 702
[ 7, 3] = 703
[ 7, 4] = 704
[ 7, 5] = 705
Library view:
[-5,-5] = -505
[-5,-4] = -504
[-5,-3] = -503
[-5,-2] = -502
[-5,-1] = -501
[-5, 0] = -500
[-5, 1] = -499
[-5, 2] = -498
[-5, 3] = -497
[-5, 4] = -496
[-5, 5] = -495
[-5, 6] = -494
[-5, 7] = -493
[-5, 8] = -492
[-5, 9] = -491
[-5,10] = -490
[-4,-5] = -405
[-4,-4] = -404
[-4,-3] = -403
[-4,-2] = -402
[-4,-1] = -401
[-4, 0] = -400
[-4, 1] = -399
[-4, 2] = -398
[-4, 3] = -397
[-4, 4] = -396
[-4, 5] = -395
[-4, 6] = -394
[-4, 7] = -393
[-4, 8] = -392
[-4, 9] = -391
[-4,10] = -390
[-3,-5] = -305
[-3,-4] = -304
[-3,-3] = -303
[-3,-2] = -302
[-3,-1] = -301
[-3, 0] = -300
[-3, 1] = -299
[-3, 2] = -298
[-3, 3] = -297
[-3, 4] = -296
[-3, 5] = -295
[-3, 6] = -294
[-3, 7] = -293
[-3, 8] = -292
[-3, 9] = -291
[-3,10] = -290
[-2,-5] = -205
[-2,-4] = -204
[-2,-3] = -203
[-2,-2] = -202
[-2,-1] = -201
[-2, 0] = -200
[-2, 1] = -199
[-2, 2] = -198
[-2, 3] = -197
[-2, 4] = -196
[-2, 5] = -195
[-2, 6] = -194
[-2, 7] = -193
[-2, 8] = -192
[-2, 9] = -191
[-2,10] = -190
[-1,-5] = -105
[-1,-4] = -104
[-1,-3] = -103
[-1,-2] = -102
[-1,-1] = -101
[-1, 0] = -100
[-1, 1] = -99
[-1, 2] = -98
[-1, 3] = -97
[-1, 4] = -96
[-1, 5] = -95
[-1, 6] = -94
[-1, 7] = -93
[-1, 8] = -92
[-1, 9] = -91
[-1,10] = -90
[ 0,-5] = -5
[ 0,-4] = -4
[ 0,-3] = -3
[ 0,-2] = -2
[ 0,-1] = -1
[ 0, 0] = 0
[ 0, 1] = 1
[ 0, 2] = 2
[ 0, 3] = 3
[ 0, 4] = 4
[ 0, 5] = 5
[ 0, 6] = 6
[ 0, 7] = 7
[ 0, 8] = 8
[ 0, 9] = 9
[ 0,10] = 10
[ 1,-5] = 95
[ 1,-4] = 96
[ 1,-3] = 97
[ 1,-2] = 98
[ 1,-1] = 99
[ 1, 0] = 100
[ 1, 1] = 101
[ 1, 2] = 102
[ 1, 3] = 103
[ 1, 4] = 104
[ 1, 5] = 105
[ 1, 6] = 106
[ 1, 7] = 107
[ 1, 8] = 108
[ 1, 9] = 109
[ 1,10] = 110
[ 2,-5] = 195
[ 2,-4] = 196
[ 2,-3] = 197
[ 2,-2] = 198
[ 2,-1] = 199
[ 2, 0] = 200
[ 2, 1] = 201
[ 2, 2] = 202
[ 2, 3] = 203
[ 2, 4] = 204
[ 2, 5] = 205
[ 2, 6] = 206
[ 2, 7] = 207
[ 2, 8] = 208
[ 2, 9] = 209
[ 2,10] = 210
[ 3,-5] = 295
[ 3,-4] = 296
[ 3,-3] = 297
[ 3,-2] = 298
[ 3,-1] = 299
[ 3, 0] = 300
[ 3, 1] = 301
[ 3, 2] = 302
[ 3, 3] = 303
[ 3, 4] = 304
[ 3, 5] = 305
[ 3, 6] = 306
[ 3, 7] = 307
[ 3, 8] = 308
[ 3, 9] = 309
[ 3,10] = 310
[ 4,-5] = 395
[ 4,-4] = 396
[ 4,-3] = 397
[ 4,-2] = 398
[ 4,-1] = 399
[ 4, 0] = 400
[ 4, 1] = 401
[ 4, 2] = 402
[ 4, 3] = 403
[ 4, 4] = 404
[ 4, 5] = 405
[ 4, 6] = 406
[ 4, 7] = 407
[ 4, 8] = 408
[ 4, 9] = 409
[ 4,10] = 410
[ 5,-5] = 495
[ 5,-4] = 496
[ 5,-3] = 497
[ 5,-2] = 498
[ 5,-1] = 499
[ 5, 0] = 500
[ 5, 1] = 501
[ 5, 2] = 502
[ 5, 3] = 503
[ 5, 4] = 504
[ 5, 5] = 505
[ 5, 6] = 506
[ 5, 7] = 507
[ 5, 8] = 508
[ 5, 9] = 509
[ 5,10] = 510
[ 6,-5] = 595
[ 6,-4] = 596
[ 6,-3] = 597
[ 6,-2] = 598
[ 6,-1] = 599
[ 6, 0] = 600
[ 6, 1] = 601
[ 6, 2] = 602
[ 6, 3] = 603
[ 6, 4] = 604
[ 6, 5] = 605
[ 6, 6] = 606
[ 6, 7] = 607
[ 6, 8] = 608
[ 6, 9] = 609
[ 6,10] = 610
[ 7,-5] = 695
[ 7,-4] = 696
[ 7,-3] = 697
[ 7,-2] = 698
[ 7,-1] = 699
[ 7, 0] = 700
[ 7, 1] = 701
[ 7, 2] = 702
[ 7, 3] = 703
[ 7, 4] = 704
[ 7, 5] = 705
[ 7, 6] = 706
[ 7, 7] = 707
[ 7, 8] = 708
[ 7, 9] = 709
[ 7,10] = 710
[ 8,-5] = 795
[ 8,-4] = 796
[ 8,-3] = 797
[ 8,-2] = 798
[ 8,-1] = 799
[ 8, 0] = 800
[ 8, 1] = 801
[ 8, 2] = 802
[ 8, 3] = 803
[ 8, 4] = 804
[ 8, 5] = 805
[ 8, 6] = 806
[ 8, 7] = 807
[ 8, 8] = 808
[ 8, 9] = 809
[ 8,10] = 810
[ 9,-5] = 895
[ 9,-4] = 896
[ 9,-3] = 897
[ 9,-2] = 898
[ 9,-1] = 899
[ 9, 0] = 900
[ 9, 1] = 901
[ 9, 2] = 902
[ 9, 3] = 903
[ 9, 4] = 904
[ 9, 5] = 905
[ 9, 6] = 906
[ 9, 7] = 907
[ 9, 8] = 908
[ 9, 9] = 909
[ 9,10] = 910
[10,-5] = 995
[10,-4] = 996
[10,-3] = 997
[10,-2] = 998
[10,-1] = 999
[10, 0] = 1000
[10, 1] = 1001
[10, 2] = 1002
[10, 3] = 1003
[10, 4] = 1004
[10, 5] = 1005
[10, 6] = 1006
[10, 7] = 1007
[10, 8] = 1008
[10, 9] = 1009
[10,10] = 1010
[11,-5] = 1095
[11,-4] = 1096
[11,-3] = 1097
[11,-2] = 1098
[11,-1] = 1099
[11, 0] = 1100
[11, 1] = 1101
[11, 2] = 1102
[11, 3] = 1103
[11, 4] = 1104
[11, 5] = 1105
[11, 6] = 1106
[11, 7] = 1107
[11, 8] = 1108
[11, 9] = 1109
[11,10] = 1110
[12,-5] = 1195
[12,-4] = 1196
[12,-3] = 1197
[12,-2] = 1198
[12,-1] = 1199
[12, 0] = 1200
[12, 1] = 1201
[12, 2] = 1202
[12, 3] = 1203
[12, 4] = 1204
[12, 5] = 1205
[12, 6] = 1206
[12, 7] = 1207
[12, 8] = 1208
[12, 9] = 1209
[12,10] = 1210
==26293==
==26293== HEAP SUMMARY:
==26293== in use at exit: 29,341 bytes in 374 blocks
==26293== total heap usage: 452 allocs, 78 frees, 36,581 bytes allocated
==26293==
==26293== LEAK SUMMARY:
==26293== definitely lost: 0 bytes in 0 blocks
==26293== indirectly lost: 0 bytes in 0 blocks
==26293== possibly lost: 0 bytes in 0 blocks
==26293== still reachable: 4,096 bytes in 1 blocks
==26293== suppressed: 25,245 bytes in 373 blocks
==26293== Rerun with --leak-check=full to see details of leaked memory
==26293==
==26293== For counts of detected and suppressed errors, rerun with: -v
==26293== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
$
$ gcc -g -O3 -std=c99 -Wall -Wextra -Wmissing-prototypes -Wstrict-prototypes -Werror \
> 2dv.c -o 2dv
#include <stdio.h>
#include <stdlib.h>
static void dump_vla_1(int x_size, int y_size, int vla[x_size][y_size]);
static void dump_vla_2(int x_min, int y_min, int x_size, int y_size,
int vla[x_size][y_size]);
static void dump_vla_3(int x_min, int x_max, int y_min, int y_max,
int x_size, int y_size, int vla[x_size][y_size]);
int main(void)
{
int extra = 3;
int x_base = 5;
int y_base = 4;
int x_size = x_base + 2 * extra;
int y_size = y_base + 2 * extra;
int (*vla)[x_size][y_size] = calloc(x_size * y_size, sizeof(int));
for (int i = 0; i < x_size; i++)
for (int j = 0; j < y_size; j++)
(*vla)[i][j] = (i + 1) * 100 + (j + 1);
for (int i = 0; i < x_size; i++)
{
for (int j = 0; j < y_size; j++)
printf(" %4d", (*vla)[i][j]);
putchar('\n');
}
dump_vla_1(x_size, y_size, *vla);
dump_vla_2(0, 0, x_size, y_size, *vla);
/* Harsh cast! */
int (*vla_2)[x_size][y_size] = (int (*)[x_size][y_size])&(*vla)[extra][extra];
dump_vla_2(-extra, -extra, x_size, y_size, *vla_2);
dump_vla_3(-extra, x_size - extra, -extra, y_size - extra, x_size, y_size, *vla_2);
dump_vla_3(0, x_base, 0, y_base, x_size, y_size, *vla_2);
free(vla);
return 0;
}
static void dump_vla_1(int x_size, int y_size, int vla[x_size][y_size])
{
printf("Matrix %dx%d\n", x_size, y_size);
for (int i = 0; i < x_size; i++)
{
for (int j = 0; j < y_size; j++)
printf(" %4d", vla[i][j]);
putchar('\n');
}
}
static void dump_vla_2(int x_min, int y_min, int x_size, int y_size,
int vla[x_size][y_size])
{
printf("Matrix %dx%d (%d..%d, %d..%d)\n",
x_size, y_size, x_min, x_min + x_size - 1, y_min, y_min + y_size - 1);
for (int i = x_min; i < x_min + x_size; i++)
{
for (int j = y_min; j < y_min + y_size; j++)
printf(" %4d", vla[i][j]);
putchar('\n');
}
}
static void dump_vla_3(int x_min, int x_max, int y_min, int y_max,
int x_size, int y_size, int vla[x_size][y_size])
{
printf("Matrix %dx%d (%d..%d, %d..%d)\n",
x_size, y_size, x_min, x_max, y_min, y_max);
for (int i = x_min; i < x_max; i++)
{
for (int j = y_min; j < y_max; j++)
printf(" %4d", vla[i][j]);
putchar('\n');
}
}
101 102 103 104 105 106 107 108 109 110
201 202 203 204 205 206 207 208 209 210
301 302 303 304 305 306 307 308 309 310
401 402 403 404 405 406 407 408 409 410
501 502 503 504 505 506 507 508 509 510
601 602 603 604 605 606 607 608 609 610
701 702 703 704 705 706 707 708 709 710
801 802 803 804 805 806 807 808 809 810
901 902 903 904 905 906 907 908 909 910
1001 1002 1003 1004 1005 1006 1007 1008 1009 1010
1101 1102 1103 1104 1105 1106 1107 1108 1109 1110
Matrix 11x10
101 102 103 104 105 106 107 108 109 110
201 202 203 204 205 206 207 208 209 210
301 302 303 304 305 306 307 308 309 310
401 402 403 404 405 406 407 408 409 410
501 502 503 504 505 506 507 508 509 510
601 602 603 604 605 606 607 608 609 610
701 702 703 704 705 706 707 708 709 710
801 802 803 804 805 806 807 808 809 810
901 902 903 904 905 906 907 908 909 910
1001 1002 1003 1004 1005 1006 1007 1008 1009 1010
1101 1102 1103 1104 1105 1106 1107 1108 1109 1110
Matrix 11x10 (0..10, 0..9)
101 102 103 104 105 106 107 108 109 110
201 202 203 204 205 206 207 208 209 210
301 302 303 304 305 306 307 308 309 310
401 402 403 404 405 406 407 408 409 410
501 502 503 504 505 506 507 508 509 510
601 602 603 604 605 606 607 608 609 610
701 702 703 704 705 706 707 708 709 710
801 802 803 804 805 806 807 808 809 810
901 902 903 904 905 906 907 908 909 910
1001 1002 1003 1004 1005 1006 1007 1008 1009 1010
1101 1102 1103 1104 1105 1106 1107 1108 1109 1110
Matrix 11x10 (-3..7, -3..6)
101 102 103 104 105 106 107 108 109 110
201 202 203 204 205 206 207 208 209 210
301 302 303 304 305 306 307 308 309 310
401 402 403 404 405 406 407 408 409 410
501 502 503 504 505 506 507 508 509 510
601 602 603 604 605 606 607 608 609 610
701 702 703 704 705 706 707 708 709 710
801 802 803 804 805 806 807 808 809 810
901 902 903 904 905 906 907 908 909 910
1001 1002 1003 1004 1005 1006 1007 1008 1009 1010
1101 1102 1103 1104 1105 1106 1107 1108 1109 1110
Matrix 11x10 (-3..8, -3..7)
101 102 103 104 105 106 107 108 109 110
201 202 203 204 205 206 207 208 209 210
301 302 303 304 305 306 307 308 309 310
401 402 403 404 405 406 407 408 409 410
501 502 503 504 505 506 507 508 509 510
601 602 603 604 605 606 607 608 609 610
701 702 703 704 705 706 707 708 709 710
801 802 803 804 805 806 807 808 809 810
901 902 903 904 905 906 907 908 909 910
1001 1002 1003 1004 1005 1006 1007 1008 1009 1010
1101 1102 1103 1104 1105 1106 1107 1108 1109 1110
Matrix 11x10 (0..5, 0..4)
404 405 406 407
504 505 506 507
604 605 606 607
704 705 706 707
804 805 806 807