void* realloc(void* ptr, unsigned newsize);
void* malloc(unsigned size);
void* alloca(unsigned size);
void* calloc(size_t numElements, size_t sizeOfElement);
都在stdlib.h函数库内
alloca 和malloc 的 区别我是alloca是在栈上申请
malloc是在堆上申请
alloca
is not Standard and
cannot be used in programs which must be widely
portable,
no matter how useful it might be.
Now that C99 supports variable-length arrays (VLA's),
they can be used to more cleanly accomplish
most of the tasks which alloca
used to be put to.
void fun()
{
int size = INT_MAX / 8;
char a[size];
}