struct R{

   unsigned int opcode: 6;
   unsigned int rs: 5;
   unsigned int rt: 5;
   unsigned int rd: 5;
   unsigned int shamt: 5;
   unsigned int funct: 6;


};

struct R test  = {32,0,11,21,19,0}

FILE *fp = fopen("./result", "rb");
fwrite(&test,sizeof(test),1,result);

00000000: 00100000 01011000 01110101 00000010

00000000: 00100000 10100000 01110011 00000001

struct R{

   char opcode[6];
   char rs[5];
   char rt[5];
   char rd[5];
   char shamt[5];
   char funct[6];


};