Three points on one straight line in language C

Language

C
Description

Given three points (x1, y1), (x2, y2), and (x3, y3), check if all the three points fall on one straight line.

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#include <stdio.h>

#include <stdlib.h>

int main (void)

{

    float slope1, slope2, x1, x2, x3;

    float y1, y2, y3;

    printf ("Enter the value of x1: ");

    scanf ("%f", &x1);

    (void) getchar ();

    printf ("Enter the value of x2: ");

    scanf ("%f", &x2);

    (void) getchar ();

    printf ("Enter the value of x3: ");

    scanf ("%f", &x3);

    (void) getchar ();

    printf ("Enter the value of y1: ");

    scanf ("%f", &y1);

    (void) getchar ();

    printf ("Enter the value of y2: ");

    scanf ("%f", &y2);

    (void) getchar ();

    printf ("Enter the value of y3: ");

    scanf ("%f", &y3);

    (void) getchar ();

    slope1=(y1-y2)/(x1-x2);

    slope2=(y2-y3)/(x2-x3);

    if(slope1==slope2&&y1-slope1*x1&&y3-slope2*x3)

        printf ("The three points fall on one straight line.\n");

    else

        printf ("The three points do not fall on one straight line.\n");

    printf ("Value of slope1: %g\n", slope1);

    printf ("Value of slope2: %g\n", slope2);

    putchar ('\n');

    system ("pause");

    return EXIT_SUCCESS;

}