calloc, malloc, free, realloc - Allocate and free dynamic memory
1.calloc: void*calloc(size_tnmemb,size_tsize); calloc() allocatesmemoryforanarrayofnmembelementsofsizebytes eachandreturnsapointertotheallocatedmemory. Thememoryissetozero. 函数:calloc(nmemb,size