Thread: Need help Vertices program

I need help with my C program that reads the coordinates of the vertices of a polygon from a file?
and computes the perimeter of the polygon.

i got the basic program down i just get a weird error message about my distance formula function dist.

heres my program:

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

int main(void)
{

typedef struct {double x, y; } vertex_t;
vertex_t temps;
FILE *file;
char flnm [64];
double perim;
vertex_t vertexs[20];
double x; double y;


printf("Enter the file name: "); /*gets file name*/
scanf("%s",flnm);

file = fopen(flnm, "r");

double temps3;
int input_status = fscanf(file,"%lf",&temps3);

perim = 0;
int i = 0;
while(input_status != EOF)
{
input_status = fscanf(file, "%lf %lf",&x,&y);/*puts the points in the array*/
temps.x = x;
temps.y = y;
vertexs[i] = temps;
i++;
}

for(i=0;i<19;i++)
{
perim += dist(vertexs[i], vertexs[i+1]);
}

perim += dist(vertexs[0], vertexs[19]);

printf("The perimeter is %f",perim);

fclose(file);
return 1;
}

double dist (vertex_t a, vertex_t b)/*gets the distance between two vertices*/
{

double distan;

distan = sqrt(((b.x - a.x)^2) + ((b.y - a.y)^2));
return distan;

}


the error messages i get are:

[leahyp@pc20 hw8]$ gcc -Wall polygon.c
polygon.c: In function 'main':
polygon.c:39: warning: implicit declaration of function 'dist'
polygon.c: At top level:
polygon.c:50: error: expected ')' before 'a'


please help me find whats wrong. i'm pretty sure its my distance function dist but idk what to do to fix it.

omg haha thanks alot that makes complete sense. appreciate it alot!

i moved it outside... but it's still not working :/

Code:

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

typedef struct {double x,y;} vertext_t;    <-------


int main(void)
{

  vertext_t vertexes[20];

and now i get a BUNCH of errors and warnings

Code:

polygon.c: In function 'main':
polygon.c:41: warning: implicit declaration of function 'dist'
polygon.c: At top level:
polygon.c:52: error: conflicting types for 'dist'
polygon.c:41: note: previous implicit declaration of 'dist' was here
polygon.c: In function 'dist':
polygon.c:57: error: invalid operands to binary ^ (have 'double' and 'int')
polygon.c:57: error: invalid operands to binary ^ (have 'double' and 'int')

alright i fixed the exponent problem and declared a prototype but i keep getting this weird error:

Code:

polygon.c:6: error: expected ')' before 'a'
polygon.c: In function 'main':
polygon.c:43: warning: implicit declaration of function 'dist'
polygon.c: At top level:
polygon.c:54: error: conflicting types for 'dist'
polygon.c:43: note: previous implicit declaration of 'dist' was here

nevermind got it i just had to switch the order. nevermind