/*  Name: Lei Hong Wei             Class: P1H1              Date: 2 Dec 2016
    This program displays the menu for user to imput a choice.
*/
#include <stdio.h>
#include <math.h>
void main(void)
{
    char C;
    int x1, x2, y1, y2;
    float gradient, dist;

    printf("Menu\n");
    printf("0. Exit\n");
    printf("1. Calculate the distance between 2 points\n");
    printf("2. Calculate the slope of 2 points\n");
    printf("\nEnter your choice: ");
    scanf("%c", &C);

    if(C=='0')
    {
        printf("\nBye-bye\n");
    }
    else if(C=='1')
    {
        printf("\nEnter the first point (x1, y1): ");
        scanf("%d %d", &x1, &y1);
        printf("Enter the second point (x2, y2): ");
        scanf("%d %d",  &x2, &y2);

        dist = sqrt(((x2-x1)*(x2-x1))+((y2-y1)*(y2-y1)));

        printf("\nDistance between the two points is %.2f.\n", dist);
    }
    else if(C=='2')
    {
        printf("\nEnter the first point (x1, y1): ");
        scanf("%d %d", &x1, &y1);
        printf("Enter the second point (x2, y2): ");
        scanf("%d %d", &x2, &y2);

        printf("\nThe slope is infinity because x1=x2.\n");
    }
    else
    {
        printf("\nInvalid choice!\n");
    }
}