problems in calling variables in struct into functions in c

struct
{
    float lat_radians;          //latitude in radians
    float lon_radians;          //longtiude in radians
    float alt_radians;          //altiude in radians
    double ECEF_X;          // ECEF X in metres
    double ECEF_Y;                // ECEF Y in metres
    double ECEF_Z;                // ECEF Z in metres

} gps_position;

void main()
{
LatLongAlt_to_ECEF_coordinates(struct gps_position {float lon; float lat; float alt} arg);
}

i having error from c141: syntax error near 'struct'. i have tried to figure but could not find any solution

Please help .. thanks

Best regards kevin

---

thanks for your useful information. But i did some changes to my codes and i still having problems of error C3861: 'lla_to_ECEF': identifier not found & error C2365: 'lla_to_ECEF' : redefinition; prev开发者_StackOverflowious definition was 'formerly unknown identifier' May i know how can i correct my mistake from here? thanks kevin

#include <stdio.h>

struct gps_position
{
float alt;
float lon;
float lat;
double ECEF_x;
 };

 void main ()
 {

lla_to_ECEF (gps_position.alt);

 return;
 }

 float lla_to_ECEF (float alt)
 {

 //some calculate to be done

 }

---

You need to bring the declaration right after struct. See you favourite C Book for examples.

struct gps_position
{
    float lat_radians;          //latitude in radians
    float lon_radians;          //longtiude in radians
    float alt_radians;          //altiude in radians
    double ECEF_X;              // ECEF X in metres
    double ECEF_Y;              // ECEF Y in metres
    double ECEF_Z;              // ECEF Z in metres
} ;

or

typedef struct 
{
      float lat_radians;          //latitude in radians
      float lon_radians;          //longtiude in radians
      float alt_radians;          //altiude in radians
      double ECEF_X;              // ECEF X in metres
      double ECEF_Y;              // ECEF Y in metres
      double ECEF_Z;              // ECEF Z in metres
} gps_position ;

---

First off, that is not a valid way of declaring a struct try this:

struct gps_position
{
    float lat_radians;          //latitude in radians
    float lon_radians;          //longtiude in radians
    float alt_radians;          //altiude in radians
    double ECEF_X;              // ECEF X in metres
    double ECEF_Y;              // ECEF Y in metres
    double ECEF_Z;              // ECEF Z in metres

};

Second, if you want to pass a struct to a function do:

gps_position arg;

//Do assigning stuff before the function is called.

LatLongAlt_to_ECEF_coordinates(arg);

---

You want to start by giving a tag to your gps_position struct:

struct gps_position
{
    float lat_radians;          //latitude in radians
    float lon_radians;          //longtiude in radians
    float alt_radians;          //altiude in radians
    double ECEF_X;          // ECEF X in metres
    double ECEF_Y;                // ECEF Y in metres
    double ECEF_Z;                // ECEF Z in metres

};

What you had before defined a variable named gps_position, but didn't give a name to the struct itself.

void main()

Not that it's particularly relevant to the question at hand, but main should normally return an int.

{
LatLongAlt_to_ECEF_coordinates(struct gps_position {float lon; float lat; float alt} arg);
}

If you want to call a function with a gps_position, you'd normally do something like this:

struct gps_position pos;

LatLongAlt_to_ECEF_coordinates(pos);

Only in a typical case, you want to pass a pointer to the struct:

LatLongAlt_to_ECEF_coordinates(&pos); 

Personally, I think I'd separate the radian-based coordinates from the ECEF-based coordinates:

struct radian_coords { 
   float latitude, longitude, altitude;
}

struct ECEF_coords { 
   double X, Y, Z;
}

Then when you convert from one to another, you'd pass an instance of each:

struct radian_cords r_pos = { 12345.6, 23456.7, 123.4 };
struct ECEF_coords e_pos;

LatLongAlt_to_ECEF_coordinates(&r_pos, &e_pos);

Or, you could write the function to return the correct type:

e_pos = LatLongAlt_to_ECEF_coordinates(&r_pos);

In this case, your function header would look something like:

struct e_pos LatLongAlt_to_ECEF_coordinates(struct r_pos const *input) { 
    struct e_pos ret;
    // compute and assign values to ret.X, ret.Y and ret.Z
    return ret;
}

---

This will eradicate your error:

This is the right way to pass structure as arguments into function

     #include <stdio.h>
     typedef struct 
     {
        float lat_radians;          //latitude in radians
        float lon_radians;          //longtiude in radians
        float alt_radians;          //altiude in radians
        double ECEF_X;          // ECEF X in metres
        double ECEF_Y;                // ECEF Y in metres
        double ECEF_Z;                // ECEF Z in metres

      } gps_position;

    void main()
    {
        gps_position gps;
            LatLongAlt_to_ECEF_coordinates(gps);
    }