文件IO编程

#include
#include
#include
#include
#include
#include
#include


int main(int argc ,char **argv)
{
int fd,size;
char *buf = "hello,I'm Webee,This is  file io test!";
char buf_r[20];
int len = strlen(buf);


/* 首先调用open函数，如果当前目录下没有hello.c则创建
* 以读写方式打开文件，并指定权限为可读可写
*/
if((fd = open("./hello.c",O_CREAT | O_TRUNC | O_RDWR,0666))<0)
{
/* 错误处理 */
printf("open fail\n");
exit(1);
}
else
printf("open file:hello.c fd = %d\n",fd);


/* 调用write函数，将buf中的内容写入hello.c */
if((size = write(fd,buf,len) ) < 0)
{
printf("write fail\n");
exit(1);
}
else
printf("write: %s\n",buf);


/* 调用lseek函数将文件指针移到文件起始位置，并读出文件中的15个字节 */
lseek(fd,0,SEEK_SET);
if((size = read(fd,buf_r,15)) <0)
{
printf("read fail\n");
exit(1);
}
else
{
buf_r[15] = '\0';
printf("read from hello.c and the content is %s\n",buf_r);
}


/* 最后调用close函数关闭打开的文件 */
if(close(fd) < 0)
{
printf("close fail\n");
exit(1);
}
else
printf("close hello.c\n");


return 0;
}
++++++++++++++++++++++++++++++++++++++++++++++

/* file_stdio.c */
#include
#include
#include


int main(int argc ,char **argv)
{
FILE *fp;
char *buf = "hello,I'm Webee,This is  file standard io test!";
char buf_r[20];
int len = strlen(buf);


/* 调用fopen函数，如果当前目录下没有hello.c则创建，以可读可写方式打开文件*/
if((fp = fopen("./hello.c","w+")) != NULL)
{
printf("fopen success\n");
}


/* 调用fwrite函数，将buf中的内容写入hello.c */
  if((fwrite(buf,sizeof(char),len,fp) > 0))
  {
  printf("fwrite: %s\n",buf);
  }


/* 调用fseek函数将文件指针移到文件起始位置，并读出文件中的15个字节 */
fseek(fp,0,SEEK_SET);
if((fread(buf_r,sizeof(char),15,fp)) <0)
{
printf("fread fail\n");
exit(1);
}
else
{
buf_r[15] = '\0';
printf("fread from hello.c and the content is %s\n",buf_r);
}


/* 最后调用close函数关闭打开的文件 */
if(fclose(fp) < 0)
{
printf("fclose fail\n");
exit(1);
}
else
printf("fclose hello.c\n");


return 0;
}