文件操作之fread()和fwrite()函数

size_t  fwrite( const void *buffer, size_t size, size_t count, FILE *stream );
buffer-指向要写数据的存储位置
size-目标所占字节数
count-写目标的最大数量，即写入多少个size大小的数据
stream-文件结构指针

举例：

定义一个结构体

struct student
{
	int      nID; //学号
	char     chName[20];    //姓名
	float    fScores[2];    //2门课的成绩
};

 void main()
 {
 	int i=0;
 	FILE *fp;
 	struct student tStu[3]={{1,"jx",99,100},
 	                        {2, "slkd",89, 90},
 	                        {3, "sldd", 100, 78}};//结构体数组
 	if((fp = fopen("F:\\1.txt", "wb")) == 0)
  	{
  		printf("func fopen() err!\n");
  		return;
  	}
  	for(i=0; i<3; i++)
  	{
  		if(fwrite(&tStu[i],sizeof(struct student),1,fp)!=1)
  		{
  			printf("func fwrite() err !\n");
  			return;
  		}
  	}

  	fclose(fp);
  }

以上代码在F盘写入二进制数据

下面用fread()函数读出：

size_t  fread( void *buffer, size_t size, size_t count, FILE *stream );
buffer-指向数据的存储位置
size-目标所占字节数
count-读取目标的最大数量，即读取多少个size大小的数据
stream-文件结构指针

void main()
{
	FILE *pRead;
	struct student tStu[4];//结构体数组
	struct student *ptStu = NULL;
	int nCount = 0;

	//打开文件 用于读取
	pRead=fopen("F:/1.txt","rb");
	if(NULL == pRead)
	{
		printf("func fopen() err ! \n");
		return;
	}
	//一条条的读取
	ptStu = tStu;
	nCount = fread(ptStu,sizeof(struct student),1,pRead);
	while(nCount>0)
	{
		printf("%d %s %.1f %.1f\n",ptStu->nID,ptStu->chName,
			ptStu->fScores[0],ptStu->fScores[1]);
		ptStu++;
		nCount = fread(ptStu,sizeof(struct student),1,pRead);
	}

	fclose(pRead);
}

结果如下：