#include <stdio.h>
#include <stdlib.h>

typedef struct opent_response {
  float x, y, z, yaw, pitch, roll;
}opent_t;

int main ( void ) {

  opent_t opent_s = {0};
  const char *x = "12.43";
  const char *y = "10.21";
  const char *z = "0.25";

  opent_s.x = atof(x);
  opent_s.y = atof(y);
  opent_s.z = atof(z);

  printf("%f\n", opent_s.x);
  printf("%f\n", opent_s.y);
  printf("%f\n", opent_s.z);
  // и т.д
  return 0;
}