1. csv文件簡介

逗號分隔值（Comma-Separated Values，CSV，有時也稱為字符分隔值，因為分隔字符也可以不是逗號），其文件以純文本形式存儲表格數據（數字和文本）。純文本意味著該文件是一個字符序列，不含必須像二進制數字那樣被解讀的數據。CSV文件由任意數目的記錄組成，記錄間以某種換行符分隔；每條記錄由字段組成，字段間的分隔符是其它字符或字符串，最常見的是逗號或制表符。通常，所有記錄都有完全相同的字段序列。通常都是純文本文件。建議使用WORDPAD或是記事本來開啟，再則先另存新檔后用EXCEL開啟，也是方法之一。
CSV文件格式的通用標準并不存在，但是在RFC 4180中有基礎性的描述。使用的字符編碼同樣沒有被指定，但是bitASCII是最基本的通用編碼。

2.csv文件信息

?1.通過excel打開文件

?2.通過Notepad++打開或記事本打開

3.讀取csv文件示例

#include 
#include 
#include 
#include 
#include 
/*
"APPID","人臉庫","創建時間","用戶組ID","修改時間","用戶ID","修改時間","人臉url"
"25497897","人臉識別","2022-01-11 16:09:21","wbyq","2022-01-13 11:02:50","18679314703","2022-01-13 11:00:52","https://console.bce.baidu.com/ai/s/facelib/face?appId=3028051&groupId=wbyq&uid=18679514703&faceId=070f81ef00383d7c376aac1c38b73090"
"25497897","人臉識別","2022-01-11 16:09:21","wbyq","2022-01-13 11:02:50","18659514703","2022-01-13 11:00:52","https://console.bce.baidu.com/ai/s/facelib/face?appId=3028051&groupId=wbyq&uid=18679514703&faceId=f83fc8ca898f4d4a2a17ef4dc341187e"
"25497897","人臉識別","2022-01-11 16:09:21","wbyq","2022-01-13 11:02:50","18679514703","2022-01-13 11:00:52","https://console.bce.baidu.com/ai/s/facelib/face?appId=3028051&groupId=wbyq&uid=18679514703&faceId=65041fdb1f58fbd6c3b983045b8f840a"
"25497897","人臉識別","2022-01-11 16:09:21","wbyq","2022-01-13 11:02:50","18679214703","2022-01-13 11:00:52","https://console.bce.baidu.com/ai/s/facelib/face?appId=3028051&groupId=wbyq&uid=18679514703&faceId=39555691bf84a277bee85a2f1cd09e68"
"25497897","人臉識別","2022-01-11 16:09:21","wbyq","2022-01-13 11:02:50","18671514703","2022-01-13 11:00:52","https://console.bce.baidu.com/ai/s/facelib/face?appId=3028051&groupId=wbyq&uid=18679514703&faceId=0ff8d148721ae720c5815934929e77b3"
"25497897","人臉識別","2022-01-11 16:09:21","wbyq","2022-01-13 11:02:50","18679513703","2022-01-13 11:00:52","https://console.bce.baidu.com/ai/s/facelib/face?appId=3028051&groupId=wbyq&uid=18679514703&faceId=aebc792d6c5fec000be59a934dfd28c3"
*/
int readfile_csv(char *filename)
{
	char c;
	FILE *fp = fopen(filename,"rb");
	int file_line=1,file_row=0;
	fseek(fp,0,SEEK_END);
	long flen = ftell(fp);
	printf("len = %ld\n",flen);
	fseek(fp,0,SEEK_SET);
	int fd=fileno(fp);//文件指針轉文件描述符	
	if(fd==-1)
	{
		printf("轉換失敗\n");
		return -1;
	}	
	char *file_addr=mmap(NULL,flen,PROT_READ,MAP_SHARED,fd,0);//內存映射
	fclose(fp);
	close(fd);	
	if(file_addr==NULL)
	{
		printf("映射失敗\n");
		return -2;
	}
	/*統計行*/
	char *p=file_addr;
	p=strstr(file_addr,""");
	while(*p)
	{
		if(*p=='\n')
		{
			p=strstr(p,""");
			if(p==NULL)break;
			file_line++;
		}
		else p++;
	}
	printf("行：%d\n",file_line);//統計行
	//"APPID","人臉庫","創建時間","用戶組ID","修改時間","用戶ID","修改時間","人臉url"
	/*統計列*/
	int cnt=0;
	p=file_addr;
	p=strstr(file_addr,""");
	p++;
	while(*p && *p!='\n')
	{
		while(*p!='"' && *p)p++;
		p++;
		cnt++;
		if(*p=='\n')break;
		else if(*p==',')p+=2;
	}
	printf("列:%d\n",cnt);
	/*將.csv文件數據保存到數組中*/
	char buff[file_line][cnt][500];
	int i,j;
	p=strstr(file_addr,""");
	p++;
	for(i=0;i

運行結果:

4.修改CSV文件

/*
函數功能：修改csv文件
形參：filename --文件名
      line  --要修改的行(從1開始)
	  row   --要修改的列(從1開始)
	  data  --修改的內容
返回值:成功返回0，失敗返回負數
*/
int modifyfile_csv(char *filename,int line,int row,char *data)
{
	char c;
	FILE *fp = fopen(filename,"rb");
	int file_line=1,file_row=0;
	fseek(fp,0,SEEK_END);
	long flen = ftell(fp);
	printf("len = %ld\n",flen);
	fseek(fp,0,SEEK_SET);
	int fd=fileno(fp);//文件指針轉文件描述符	
	if(fd==-1)
	{
		printf("轉換失敗\n");
		return -1;
	}	
	char *file_addr=mmap(NULL,flen,PROT_READ,MAP_SHARED,fd,0);//內存映射
	fclose(fp);
	close(fd);	
	if(file_addr==NULL)
	{
		printf("映射失敗\n");
		return -2;
	}
	/*統計行*/
	char *p=file_addr;
	p=strstr(file_addr,""");
	
	while(*p)
	{
		if(*p=='\n')
		{
			p=strstr(p,""");
			if(p==NULL)break;
			file_line++;
		}
		else p++;
	}
	printf("行：%d\n",file_line);//統計行
	
	//"APPID","人臉庫","創建時間","用戶組ID","修改時間","用戶ID","修改時間","人臉url"
	/*統計列*/
	int cnt=0;
	p=file_addr;
	p=strstr(file_addr,""");
	p++;
	while(*p && *p!='\n')
	{
		while(*p!='"' && *p)p++;
		p++;
		cnt++;
		if(*p=='\n')break;
		else if(*p==',')p+=2;
	}
	printf("列:%d\n",cnt);
	/*將.csv文件數據保存到數組中*/
	char buff[file_line][cnt][500];
	int i,j;
	p=strstr(file_addr,""");
	p++;
	for(i=0;ifile_line || row>cnt)
	{
		printf("未找到要修改的位置\n");
		return 0;
	}
	char src_data[500];
	if(row==cnt)
	{
		snprintf(src_data,sizeof(src_data),""%s"\n",data);
	}
	else snprintf(src_data,sizeof(src_data),""%s",",data);
	strcpy(buff2[line-1][row-1],src_data);
	int size;
	for(i=0;i

運行結果：