C语言 malloc、calloc、realloc的区别

        void* malloc(unsigned size);
        void* realloc(void* ptr, unsigned newsize);  
        void* calloc(size_t numElements, size_t sizeOfElement);

                #include <stdio.h>
                #include <malloc.h>

                int main(int argc, char* argv[]) 
                { 
                    char *p,*q;
                    p = (char *)malloc(10);
                    q = p;
                    p = (char *)realloc(p,10);
                    printf("p=0x%x/n",p);
                    printf("q=0x%x/n",q);
                    
                    return 0; 
                }

                #include <stdio.h>
                #include <malloc.h>

                int main(int argc, char* argv[]) 
                { 
                    char *p,*q;
                    p = (char *)malloc(10);
                    q = p;
                    p = (char *)realloc(p,1000);
                    printf("p=0x%x/n",p);
                    printf("q=0x%x/n",q);
                    
                    return 0; 
                }