long a=;

  float b=34.56745f;

  float c=0.0;

   byte fbs[]={,,,};

   byte* t=fbs;

   float2Bytes(t,b);

   unsigned int addrF=(unsigned int) &b;

   unsigned int addrFc=(unsigned int) &c;

Serial.println(addrF);

  Serial.println(addrFc);

  float x= bytes2Float(fbs);

   for(int i=;i<;i++){

   byte bf1=*((byte*)(addrF + i));

   *((byte*)(addrFc + i))=bf1;

     Serial.print(bf1,HEX);

     if(i<)  Serial.print("-");

   }

   Serial.println(" ");

  for(int j=;j<;j++){

    Serial.print(fbs[j],HEX);

    if(j<)Serial.print("-");

  }

  Serial.println(" ");

  Serial.print("c:");

  Serial.println(c,);

  Serial.print("x:");

  Serial.println(x,);

  Serial.println(sizeof(b));

void float2Bytes(byte bytes_temp[],float float_variable){

  union {

    float a;

    byte bytes[];

  } thing;

  thing.a = float_variable;

  memcpy(bytes_temp, thing.bytes, );

}

float bytes2Float(byte bytes_temp[]){

  union {

    float a;

    byte bytes[];

  } thing;

  memcpy(thing.bytes,bytes_temp,  );

  return thing.a;

}

//查找字节数组中是否以指定的字符串开头

boolean bStartsWith(byte data[],int len, String fStr){

    int fLen=fStr.length() ;

   byte fBytes[fLen + ];

   fStr.getBytes(fBytes,fLen+);

   if(len<=)return false;

   if(len<fLen)return false;

   byte flag=;

   for(int j=;j<fLen;j++){

       if(fBytes[j]!=data[j])

       {

                flag=;

                break;

        }

    }

   if(flag) return true; 

   return false;

}

 void long2byte(unsigned long res,byte targets[] ) {

        targets[] = (byte) (res & 0xff);

        targets[] = (byte) ((res >> ) & 0xff);

        targets[] = (byte) ((res >> ) & 0xff);

        targets[] = (byte) (res >> );

    }  

unsigned long bytes2long(byte buf[]) {

        unsigned long firstByte = ;

        unsigned long secondByte = ;

        unsigned long thirdByte = ;

        unsigned long fourthByte = ;

        int index = ;

        firstByte = (0x000000FFU & ( buf[index+]));

        secondByte = (0x000000FFU & ( buf[index + ]));

        thirdByte = (0x000000FFU & ( buf[index + ]));

        fourthByte = (0x000000FFU & ( buf[index ]));

        index = index + ;

        return ((unsigned long) (firstByte <<  | secondByte <<  | thirdByte <<  | fourthByte)) & 0xFFFFFFFFUL;

    }