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

float distance(float *x1, float *y1, float *x2, float *y2);

int main()
{ printf("Input coordinates as x1,y1,x2,y2:n");
float x1,y1,x2,y2;
scanf("%f %f %f %f ",&x1,&y1,&x2,&y2);

printf("Coordinates are : (%f,%f) and (%f,%f)n",x1,y1,x2,y2);
printf("%f",distance (&x1,&y1,&x2,&y2));
return 0;
}

float distance(float *x1, float *y1, float *x2, float *y2)
{
   float d= sqrt(pow((*x1-*x2),2)+pow((*y1-*y2),2));
printf("%f", d);
return d;
}

Input coordinates as x1,y1,x2,y2:
1 2 3 4