csv：简化版excel，在PC机上等同于excel，可进行各种excel计算、画图。

#defineEACH_FILE_MAX_BYTE52428800

//-------------------------------------------------------------------

//功能：存放数据为csv格式

//输入：filename 写入U盘的文件名称，如ai.csv。

//name 变量名称。

//value 值。

//输出：0：成功!0：失败

//备注：

//-------------------------------------------------------------------

int Hzhy_Write_CsvData(char *filename,char *name,int value)

{

int len = 0,size;

struct tm *p;

char buff[256];

time_t timep;

time(&timep);

if (InitUsb() < 0)

return -1;

p=gmtime(&timep);

size = UsbGetFileSize(filename);

if(size == 0)

{

memset(buff,0,sizeof(buff));

printf("Build new file\n");

sprintf(buff,"变量名,时间,值\n");

len = strlen(buff);

UsbWriteFile(filename,buff,len);

}

else

{

if(size > EACH_FILE_MAX_BYTE)

{

printf("Beyond the maximum byte limit !\n");

return MAX_LEN_ERROR;

}

}

/*{

static int i=0;

printf("csv%03d\n",i++);

}

*/

memset(buff,0,sizeof(buff));

sprintf(buff,"%s, %d-%d-%d %d:%d:%d,%d\n",name,(1900+p->tm_year), (1+p->tm_mon),p->tm_mday,p->tm_hour, p->tm_min, p->tm_sec,value);

len = strlen(buff);

UsbWriteFile(filename,buff,len);

return 0;

}

//-------------------------------------------------------------------

//功能：写文件(包含创建)

//输入：

//输出：>=0：写入的数目<0：失败

//备注：

//-------------------------------------------------------------------

int UsbWriteFile(char *filename, char *buf, char len)

{

int fd,ret=0;

char name[100];

if (IsUsbExist == 0)

return -1;

if (strlen(filename) > 72)

{

printf("file name too long!\n");

return -4;

}

memset(name,0,sizeof(name));

sprintf(name,usb_path);

strcat(name,filename);

//printf("path：%s\n",name);

fd = open(name,O_RDWR|O_CREAT);//写方式打开文件，如果文件不存在则创建

if((fd < 0))//打开操作不成功

{

static int cnt=0;

if (cnt == 0)

{

cnt = 1;

printf("The file can not be opened.\n");

}

return -2;

}

lseek(fd,0,SEEK_END);//文件指针移动到末尾，追加

ret = write(fd,buf,len);

if (ret < 0)

perror("write err");

close(fd);

return ret;

}

//-------------------------------------------------------------------

//功能：读文件

//输入：

//输出：>=0：读取的数目<0：失败

//备注：

//-------------------------------------------------------------------

int UsbReadFile(char *filename, char *buf, char len)

{

int fd,ret=0;

char name[100];

if (IsUsbExist == 0)

return -1;

if (strlen(filename) > 72)

{

printf("file name too long!\n");

return -4;

}

memset(name,0,sizeof(name));

sprintf(name,usb_path);

strcat(name,filename);

//printf("path：%s\n",name);

fd = open(name,O_RDONLY);

if((fd < 0))//打开操作不成功

{

static int cnt=0;

if (cnt == 0)

{

cnt = 1;

printf("The file can not be opened.\n");

}

return -2;

}

lseek(fd,0,SEEK_SET);//文件指针移动到开头

ret = read(fd,buf,len);

if (ret < 0)

perror("read err");

close(fd);

printf("read Result:\n%s\n",buf);

return ret;

}

//-------------------------------------------------------------------

//功能：获取文件大小

//输入：

//输出：文件大小

//备注：

//-------------------------------------------------------------------

int UsbGetFileSize(char *filename)

{

int fd,size=0;

char name[100];

if (IsUsbExist == 0)

return -1;

if (strlen(filename) > 72)

{

printf("file name too long!\n");

return -4;

}

memset(name,0,sizeof(name));

sprintf(name,usb_path);

strcat(name,filename);

//printf("path：%s\n",name);

fd = open(name,O_RDONLY);

if((fd < 0))//打开操作不成功

{

static int cnt=0;

if (cnt == 0)

{

cnt = 1;

printf("The file can not be opened.\n");

}

return -2;

}

size = lseek(fd,0,SEEK_END);//文件指针移动到末尾

if (size < 0)

perror("get size err");

close(fd);

//printf("size=%d\n",size);

return size;

}