十六进制文本转字符存储到二进制文件

#include <stdio.h>

#include <string.h>
#include <stdlib.h>  
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>

//采用C模式读二进制文件
void DataRead_CMode()
{
    FILE *fid;
    fid = fopen("binary.dat","rb");
     if(fid == NULL)
     {
      printf("读取文件出错");
      return;
      }

    unsigned char pos[8];
    fread(pos,sizeof(unsigned char),10,fid);
    for(int i = 0; i < 8; i++)
      printf("read ret: %02x\n", pos[i]);

    fclose(fid);
 }

//将两个字符合成一个字符数据
unsigned char trans(char * buffer)
{
    unsigned char temp = 0;
    for(int i = 0; i < 2; i++)
    {
      temp = temp << 4;

    if(buffer[i] >= '0' && buffer[i] <= '9')
    {
        temp += buffer[i] - 0x30;
    }
    else if(buffer[i] >= 'a' && buffer[i] <= 'f')
    {
        temp += buffer[i] - 0x61 + 0x0a;
    }
    else if(buffer[i] >= 'A' && buffer[i] <= 'F')
    {
        temp += buffer[i] - 0x41 + 0x0a;
    }
    else
    {
      printf("get wrong value: %02X ,file: %s ,line: %d\n",buffer[i],__FILE__,__LINE__);
    }
  }

   return temp;
}

char str[] = "ffaa56fc010100ff";

 void main()
{

  //写数据
    FILE *fid;
    fid = fopen("binary.dat","wb");
   if(fid == NULL)
   {
     printf("写出文件出错");
     return;
  }

    for(int i=0; i< strlen(str); i+=2)
  {
      unsigned char tmp = trans(&str[i]);
      printf("src: %02X \n",tmp);

      fwrite(&tmp,sizeof(unsigned char),1,fid);
  }

    fclose(fid);

    DataRead_CMode();
}