Thread: please tell me how to rectify my code

Code:

i am not very knowledgeable on structures.
i want to input x1,y1 of one point and x2,y2 of other and get the distance.

this is my code but i am getting error.

#include <stdio.h>
#include <math.h> 

struct position{
	double latitude;
	double longitude;
};

void main()
{	
	double distance;
	struct position p1,p2;
	scanf( "%lf, %lf", p1, p2);
	distance = sqrt( (p1.latitude * p1.longitude) + (p2.latitude * p2.longitude));
	printf(" %lf", distance);
}

You should be reading into the members of p1 and p2, not directly into p1 and p2.

Also, post your well indented code within [code][/code] bbcode tags, and use int main instead of void main.

Originally Posted by ilikeapplepie

when i read directly into the member, i get an error - undeclared identifier.

Post your code.

Originally Posted by ilikeapplepie

also i need to scanf 4 values. so do i need %lf 4 times inside scanf function?

Yes.

Code:

#include <stdio.h>
#include <math.h> 

struct position{
          double latitude;
	  double longitude;
};



int  main(void)
{	
	  double distance;
	  struct position p1,p2;
	  scanf( "%lf, %lf, %lf, %lf", p1.latitude, p1.longitude, p2.latitude, p2.longitude);
	  distance = sqrt( (p1.latitude * p1.longitude) + (p2.latitude * p2.longitude));
	  printf(" %lf", distance);
}

Looks better now, except that you should have passed pointers with:

Code:

scanf("%lf, %lf, %lf, %lf", &p1.latitude, &p1.longitude, &p2.latitude, &p2.longitude);

Originally Posted by ilikeapplepie

i am sorry i don't know why the indentation disappears.
i posted my code with the proper indentations.

That is why I told you to post within [code][/code] bbcode tags

Originally Posted by ilikeapplepie

i am sorry i don't know why the indentation disappears.
i posted my code with the proper indentations.

Did you quoted in with code tags?

hmm, i added the pointers. now there is no error but i get a weird huge number like

Code:

92559631394.......

Maybe you should pass %f at printf instead of %lf. Maybe...

I tested with this program:

Code:

#include <stdio.h>
#include <math.h>

struct position{
    double latitude;
    double longitude;
};

int main(void)
{
    double distance;
    struct position p1, p2;
    scanf("%lf, %lf, %lf, %lf", &p1.latitude, &p1.longitude, &p2.latitude, &p2.longitude);
    distance = sqrt( (p1.latitude * p1.longitude) + (p2.latitude * p2.longitude));
    printf("%f\n", distance);
    return 0;
}

Entering 0, 0, 1, 1 gives the expected result of 1.000000.

latitude is x
longitude is y

The formula you're using makes no sense.

Code:

distance = sqrt(pow(x1+x2, 2)+pow(y1+y2, 2));

That's the right formula...

this is the slightly different new code.

Code:

#include <stdio.h>
#include <math.h> 

struct position{
	double latitude;
	double longitude;
};



int  main(void)
{	
	double distance_lat;
	double distance_lon;
	double distance;
	struct position p1,p2;
	scanf( "%f, %f, %f, %f", &p1.latitude, &p1.longitude, &p2.latitude, &p2.longitude);
	distance_lat=p1.latitude-p2.latitude;
	distance_lon=p1.longitude-p2.longitude;
	distance = sqrt( (distance_lat * distance_lat) + (distance_lon * distance_lon));
	printf(" %f", distance);
}

yet i get a big number. i rebuilt, debugged and ran still a big number.