[英]C 2D array Memory allocation
Greetings all, Is there any issue in the following logic for allocating 2D array: 问候,以下逻辑分配二维数组是否有任何问题:
unsigned char **
Malloc2D_uchr(int ht, int wt, unsigned char initv)
{
int h, w;
unsigned char **x;
x = (unsigned char **) malloc(sizeof(void *) * ht);
DEBUG_PRINT_MEMLOC_EXIT(x,"malloc failed (%s,%i)\n",sizeof(void *)*ht);
x[0] = (unsigned char *) malloc(sizeof(unsigned char) * ht * wt);
DEBUG_PRINT_MEMLOC_EXIT(x[0],"malloc failed (%s,%i)\n",sizeof(unsigned char)*ht*wt);
for (h = 1; h < ht; h++)
{
x[h] = x[h - 1] + wt; /* + is a pointer summation */
}
for (h = 0; h < ht; h++)
{
for (w = 0; w < wt; w++)
{
x[h][w] = initv;
}
}
return x;
}
The macro expansion is : 宏扩展为:
#define DEBUG_PRINT_MEMLOC_EXIT(t,s,z); if(t == NULL){\
printf(s,__FILE__,__LINE__,z);\
printf("Malloc size = %d\n",z);\
exit(-1);\
}
Sometimes the code crash during malloc(). 有时,代码在malloc()期间崩溃。
thanks in advance. 提前致谢。
There's nothing fundamentally wrong - that approach is perfectly cromulent. 从根本上没有什么错-这种方法是完美的。 However, you should check that the multiplications don't overflow, and your
malloc()
lines can be written in a cleaner way: 但是,您应该检查乘法不会溢出,并且您的
malloc()
行可以用一种更简洁的方式编写:
if ((ht > SIZE_MAX / sizeof x[0]) || (wt > (SIZE_MAX / sizeof x[0][0]) / ht))
/* error, too large */
x = malloc(sizeof x[0] * ht);
x[0] = malloc(sizeof x[0][0] * ht * wt);
I'm surprised it doesn't crash all the time. 我很惊讶它不会一直崩溃。 You don't return anything.
你什么也没退。
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