c/c++ 图片内存的分配，赋值，检验赋值

//以下在c++ buider调试成功。

#include

void *pImgDestBuffer;//图片分配内存首地址
 int length=3*10000*10000;//预设图片所占内存的大小，
 //假设图片w=10000,H=10000,R,G,B三色各占一个字节
 //int的范围为-2147483648 ~ 2147483647，length不会溢出

int _tmain(int argclength, _TCHAR* argv[])
{   pImgDestBuffer=malloc(length);//分配内存
    if ( pImgDestBuffer==0)
    {  return -1;  //内存没有分配成功，返回
    }
    unsigned char * tempBuffer =(unsigned char*)pImgDestBuffer ;//转换void * 到unsigned          char * unsigned char t=0;

    //赋值
    for (int i=0; i < length; i++)
    {   t= (unsigned char )128;
        *tempBuffer =t;
         tempBuffer++;//指针加1
    }

    tempBuffer=( unsigned char * ) pImgDestBuffer ;

    //打印第1个像素
    t1=*tempBuffer;
    tempBuffer++;
    t2=*tempBuffer;
    tempBuffer++;
    t3=*tempBuffer;
    tempBuffer++;
    printf("first pix:%d,%d,%dn",t1,t2,t3);

    printf("middle colmun pixes:n");
    int rowlength=  width*3;
    int Colcentre = rowlength/2;
    tempBuffer=( unsigned char * ) pImgDestBuffer;
    tempBuffer+= Colcentre;
     //打印中间列
     for (int i = 0; i < height; i++)
     {
      t1=*tempBuffer;
      tempBuffer++;
      t2=*tempBuffer;
      tempBuffer++;
      t3=*tempBuffer;
      tempBuffer++;
      tempBuffer+=rowlength;
      sprintf(str,"|%d,%d,%d| ",t1,t2,t3);
      printf(str);
     }
     printf("n");
    printf("middle row pixes:n");
    tempBuffer=( unsigned char * ) pImgDestBuffer;
    int middleRow =length/2;
    tempBuffer += middleRow;
     //打印中间行
     for (int i = 0; i < width; i++)
     {
      t1=*tempBuffer;
      tempBuffer++;
      t2=*tempBuffer;
      tempBuffer++;
      t3=*tempBuffer;
      tempBuffer++;
      sprintf(str,"|%d,%d,%d| ",t1,t2,t3);
      printf(str);
     }
     printf("n");

    free(pImgDestBuffer);//释放内存
    system("pause");
    return 0;
}