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

int main(int argc, char *argv[])
{
    float distance;   //total distance
    float x[2];          //the x coordinates
    float y[2];          //the y coordinates
    char line[100];  //the read line
    
    printf("What is x1?\n");
    fgets(line, sizeof(line), stdin);
    sscanf(line, "%f", x[0]);

   /*It segfaults here*/

    printf("\n\nWhat is x2?\n");
    fgets(line, sizeof(line), stdin);
    sscanf(line, "%f", x[1]);
    
    printf("\n\nWhat is y1?\n");
    fgets(line, sizeof(line), stdin);
    sscanf(line, "%f", y[0]);
    
    printf("\n\nWhat is y2?\n");
    fgets(line, sizeof(line), stdin);
    sscanf(line, "%f", y[1]);

    distance = sqrt(((x[1] - x[0]) * (x[1] - x[0])) + ((y[1] - y[0]) * (y[1] - y[0])));
    
    printf("\n%f", distance);
  
  system("PAUSE");	
  return 0;
}

sscanf(line, "%f", x[0]);

sscanf(line, "%f", &x[0]);