c语言中如何修改文件中间的几个字节

//程序测试结果在ubuntu linux下运行获得
#include <stdio.h>
#include <string.h>
int main()
{
  //文件原始数据
  //00 01 02 03 04 05 06 07 08 09
 
  //下面每一个fopen前面注释中的数据是以该方式打开文件，写文件之后文件的内容
   
  //00 00 00 00 CC DD
  //FILE * file = fopen("./test.data","wb+");
  
  //00 00 00 00 CC DD
  //FILE * file = fopen("./test.data","wb");
  
  //00 01 02 03 CC DD 06 07 08 09
  FILE * file = fopen("./test.data","rb+"); //这种是正确的做法
  
  //00 01 02 03 04 05 06 07 08 09
  //FILE * file = fopen("./test.data","rb");
  
  //00 01 02 03 04 05 06 07 08 09 CC DD
  //FILE * file = fopen("./test.data","ab");
  
  //00 01 02 03 04 05 06 07 08 09 CC DD
  //FILE * file = fopen("./test.data","ab+");
  
  //00 00 00 00 CC DD
  //FILE * file = fopen("./test.data","wr");
  
  //00 01 02 03 04 05 06 07 08 09
  //FILE * file = fopen("./test.data","rw");
  
  //00 01 02 03 04 05 06 07 08 09 CC DD
  //FILE * file = fopen("./test.data","aw");
  
  //00 00 00 00 CC DD
  //FILE * file = fopen("./test.data","wa");
  
  //00 01 02 03 04 05 06 07 08 09 CC DD
  //FILE * file = fopen("./test.data","ar");
  
  //00 01 02 03 04 05 06 07 08 09
  //FILE * file = fopen("./test.data","ra");
  if(file!=NULL)
  {
   char buffer[]={0xCC,0xDD};
   fseek(file,4,SEEK_SET);
   fwrite(buffer,1,sizeof(buffer),file);
   fclose(file);
  }
  return 0;
}

FILE *f = fopen( "file.name", "r+b" );
fseek( f, 3, SEEK_SET ); // move to offest 3 from begin of file
unsigned char newByte = 0x67;
fwrite( &newByte, sizeof( newByte ), 1, f );
fclose( f );