struct - Creating own float structure in C++ -

yet lectures in c++ @ university began yet got first problems. our task implement self made structure in c++ floating points via ieee 754 standard:

create data structure allows store float, read raw byte representation , internal representation s, e , m. use combination of union , bit-field-struct. write program float number assigned float part of structure , raw , s/e/m representation printed. use hexadecimal output raw , m.

what had far following:

#include <stdio.h> #include <math.h>  union {     struct kfloat {         //using bit fields our self made float. s sign, e exponent, m mantissa         //it should unsigned because use 0 , 1         unsigned int s : 1, e : 8, m : 23;     };     //one bit wasted our '.'     char internal[33]; };  float calculaterealfloat(kfloat kfloat) {     if(kfloat.s == 0) {         return (1.0+kfloat.m)*pow(2.0, (kfloat.e-127.0));     } else if (kfloat.s == 1) {         return (-1.0)*((1.0+kfloat.m)*pow(2.0, (kfloat.e-127.0)));     }     //error case when s bigger 1     return 0.0; }  int main(void) {     kfloat kf_pos = {0, 128, 1.5707963705062866};//this should pi (rounded) aka 3.1415927     kfloat kf_neg = {1, 128, 1.5707963705062866};//pi negative      float f_pos = calculaterealfloat(kf_pos);     float f_neg = calculaterealfloat(kf_neg);      printf("the positive float %f or ",f_pos);     printf("%e\n", f_pos);      printf("the negative float %f or ",f_neg);     printf("%e", f_neg);     return 0; } 

the first error code mantissa absolutely wrong have no idea how fix this.

please reread task:

create data structure allows store float, read raw byte representation , internal representation s, e , m.

this not mean should store string

i following way:

union myfloat {   unsigned char rawbytedatarep[4];   unsigned int  rawdatarep;   float         floatrep;   struct{   // not checked part copied    unsigned s : 1;    unsigned e : 8;    unsigned m : 23;   }             componentesrep; } 

but careful! besides fact union-conversion pattern used, c-standard states result undefined behaviour if read unionmember 1 written.

edit: added uint32 rep

void testmyfloat() {   myfloat mf;   mf.floatrep = 3.14;   printf("the float %f assembled sign %i magnitude 0x%08x , exponent %i , looks in memory 0x%08x.\n",         mf.floatrep,          (int)mf.componentesrep.s,          (unsigned int)mf.componentesrep.m,          (int)mf.componentesrep.e,          mf.componentesrep.rawdatarep);  }