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#1
August 25th, 2013, 10:03 PM
 WhatNow
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Join Date: Aug 2013
Posts: 16
Time spent in forums: 2 h 48 m 50 sec
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Program to calculate distance...

Here I am with another problem question...

I am writing a program to calculate the distance between two points. This is the code I have so far, but it isn't working. I'm having trouble sorting out what variable name to put where. :/ Can someone point me in the correct direction?
Code:
```#include <stdio.h>
#include <math.h>

struct point
{
float x;
float y;
};

float distance(struct point, struct point);
void enter_a_point(struct point *);

int main(void)
{
struct point p1, p2;

enter_a_point(x,y);
enter_a_point(x,y);

printf("Distance between the points = %.2f\n", distance(struct point p1, struct point p2));

return 0;
}

float distance(struct point p1, struct point p2)
{
return sqrt(pow(p2[x]-p1[x],2) + pow(p2[y]-p1[y],2));
}

void enter_a_point(struct point *p)
{
printf("\nEnter an x coordinate: ");
scanf("%f", &x);

printf("\nEnter a y coordinate: ");
scanf("%f", &y);
}```

Thank you!

#2
August 25th, 2013, 10:50 PM
 dwise1_aol
Contributing User

Join Date: Jan 2003
Location: USA
Posts: 6,842
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Code:
```float distance(struct point p1, struct point p2)
{
return sqrt(pow(p2[x]-p1[x],2) + pow(p2[y]-p1[y],2));
}```

What's x? What's y? Where are they declared and where are they initialized?

And why are you treating p1 and p2 as if they were arrays?

Code:
```void enter_a_point(struct point *p)
{
printf("\nEnter an x coordinate: ");
scanf("%f", &x);

printf("\nEnter a y coordinate: ");
scanf("%f", &y);
}```

Again, what's x and what's y and where are they declared? And why, after passing in point, you don't use it?

You access a field within a struct with dot notation. Like PersRec.name . But that only works if you have the struct itself. If you are using a pointer to a struct, eg pPersRec, then you use an arrow; eg pPersRec->name .

#3
August 26th, 2013, 03:59 AM
 WhatNow
Registered User

Join Date: Aug 2013
Posts: 16
Time spent in forums: 2 h 48 m 50 sec
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Thank you!!!

I got it working! Thank you for the help.

#4
August 27th, 2013, 07:54 PM
 b49P23TIvg
Contributing User

Join Date: Aug 2011
Posts: 4,124
Time spent in forums: 1 Month 3 Weeks 2 Days 4 h 49 m 23 sec
Reputation Power: 455
I'd use the hypot function,

distance = hypot(x1-x0, y1-y0);
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