.bmp to .tiff without any libs appart from std I/O

#include<iostream>
#include<fstream>
using namespace std;
typedef unsigned char uchar;
struct tifheader
{
    uint16_t identifier;
    uint16_t version;
    uint32_t offset;
};
struct tiftag
{
   uint16_t tagid;
   uint16_t datatype;
   uint32_t datacount;
   uint16_t dataoffset;
};
struct tiffifd
{
    uint16_t entries;
    tiftag taglist[12];
    uint16_t nextoffset;
};

int main()
{
   FILE* f=fopen("test.bmp","rb");
   if (f==NULL){ cout<<"Argument Exception"; }
   uchar header[54];
   fread(header, sizeof(uchar),54,f);
   int width=*(int*)&header[18];
   int height=*(int*)&header[22];
   int row=(width*3 +3)&(~3);
   uchar d[row*height],temp;
   fread(&d,sizeof(uchar),row*height,f);
   for(int i=0;i<height*width*3;i++)
   {
      temp=d[i];d[i]=d[i+2];d[i+2]=temp;
   }
   fclose(f);
   FILE* g=fopen("output.tiff","wb");
   tifheader tifh;
   tifh.identifier=18761;
   tifh.version=42;
   tifh.offset=8;
   tiffifd ifd;
   ifd.entries=12;
   ifd.taglist[0].tagid=256;
   ifd.taglist[1].tagid=257;
   ifd.taglist[2].tagid=258;
   ifd.taglist[3].tagid=259;
   ifd.taglist[4].tagid=262;
   ifd.taglist[5].tagid=273;
   ifd.taglist[6].tagid=277;
   ifd.taglist[7].tagid=278;
   ifd.taglist[8].tagid=279;
   ifd.taglist[9].tagid=282;
   ifd.taglist[10].tagid=283;
   ifd.taglist[11].tagid=296;
   ifd.taglist[0].datatype=3;
   ifd.taglist[1].datatype=3;
   ifd.taglist[2].datatype=3;
   ifd.taglist[3].datatype=3;
   ifd.taglist[4].datatype=3;
   ifd.taglist[5].datatype=3;
   ifd.taglist[6].datatype=3;
   ifd.taglist[7].datatype=3;
   ifd.taglist[8].datatype=3;
   ifd.taglist[9].datatype=5;
   ifd.taglist[10].datatype=5;
   ifd.taglist[11].datatype=3;
   ifd.taglist[0].datacount=1;
   ifd.taglist[1].datacount=1;
   ifd.taglist[2].datacount=3;
   ifd.taglist[3].datacount=1;
   ifd.taglist[4].datacount=1;
   ifd.taglist[5].datacount=1;
   ifd.taglist[6].datacount=1;
   ifd.taglist[7].datacount=1;
   ifd.taglist[9].datacount=1;
   ifd.taglist[10].datacount=1;
   ifd.taglist[11].datacount=1;
   ifd.taglist[0].dataoffset=width;
   ifd.taglist[1].dataoffset=height;
   ifd.taglist[2].dataoffset=8;
   ifd.taglist[3].dataoffset=1;
   ifd.taglist[4].dataoffset=2;
   ifd.taglist[5].dataoffset=156;
   ifd.taglist[6].dataoffset=3;
   ifd.taglist[7].dataoffset=height;
   ifd.taglist[8].dataoffset=row*height;
   ifd.taglist[9].dataoffset=100;
   ifd.taglist[10].dataoffset=100;
   ifd.taglist[11].dataoffset=3;
   ifd.nextoffset=0;
   fwrite(&tifh,sizeof(tifheader),1,g);
   fwrite(&ifd,sizeof(tiffifd),1,g);
   fwrite(d,sizeof(uchar),row*height,g);
   fclose(g);
}

I have to convert a .bmp file to .tiff file without using any libs apart from standard libs. It is compiling but tiff file is of wrong format. Please help I don't any problem with the code. The code basicaly takes a bmp file extract its data and writes it into a tiff file with header and IFD. There is only one IFD.