realloc_example.c

linux下的程序开发：本程序主要实现内存的分配和管理

#include <stdio.h>
#include <stdlib.h>

int main (int argc,char* argv[],char* envp[])						//(1)主函数
{
  int input;
  int n;
  int *numbers1;
  int *numbers2;
  numbers1=NULL;

  if((numbers2=(int *)malloc(5*sizeof(int)))==NULL)				//(2)numbers2指针申请空间
     {
         printf("malloc memory unsuccessful");
		free(numbers2);
		numbers2=NULL;
         exit(1);
         }
  for (n=0;n<5;n++) 										//(3)初始化
      {
      *(numbers2+n)=n;
      printf("numbers2's data: %d\n",*(numbers2+n));
      }

  printf("Enter an integer value you want to remalloc ( enter 0 to stop)\n");		//(4)新申请空间大小　
  scanf ("%d",&input);
     
  numbers1=(int *)realloc(numbers2,(input+5)*sizeof(int));				//(5)重新申请空间
  if (numbers1==NULL) { 
         printf("Error (re)allocating memory"); 
         exit (1); 
     }

  for(n=0;n<5;n++)											//(6)这5个数是从numbers2拷贝而来
    {
    printf("the numbers1s's data copy from numbers2: %d\n",*(numbers1+n));
    }

 for(n=0;n<input;n++) 										//(7)新数据初始化
  {
      *(numbers1+5+n)=n*2;
      printf ("nummber1's new data: %d\n",*(numbers1+5+n));
     // numbers1++;
  }
  printf("\n");
  free(numbers1);											//(8)释放numbers1
  numbers1=NULL;
//  free(numbers2);											//(9)不能再释放numbers2
  return 0;
}