what am i doing wrong here. it compiles and works but after you enter in
the first value it just stops.
/*
AUTHOR: Christopher A. Smith
ASSIGNMENT: Exercise 4-22 page 112
DUE DATE: Feburary 1999
PURPOSE: The purpose of this program is to read two points on a line
entered from
the keyboard, and will loop untill eof. Also it
will it will determine
whether the lines are parallel or whether they
intersect, and if they
intersect whether they are perpendicular. 'E' is
being used for testing,
there is no resone why I picked it.
*/
#include <stdio.h>
#include <stdlib.h>
#define PERP -1
int main()
{
float x1, x2,
y1, y2;
float j;
void print_user_instructions();
float read_x1( float );
float read_x2( float );
float read_y1( float );
float read_y2( float );
print_user_instructions();
if ( ( j = read_x1( x1 ) ) == 'E' );
return EXIT_FAILURE;
if ( ( j = read_y1( y1 ) ) == 'E' );
return EXIT_FAILURE;
if ( ( j = read_x2( x2 ) ) == 'E' );
return EXIT_FAILURE;
if ( ( j = read_y2( y2 ) ) == 'E' );
return EXIT_FAILURE;
}
/* FUNCTION: print_user_instructions
INPUT: none
OUTPUT: none
USE: prints out the user instrutions to the screen
*/
void print_user_instructions()
{
printf( "\nEnter 4 points for a line (1 point a time) to"
"be tested for: parallel, perpendicular, or if"
"they intersect. To exit the program press eof,"
"(ex. ctrl z for DOS) or type quit at any time.\n" );
}
/* FUNTION: read_x1
INPUT: prompt user for x1
OUTPUT: returns the values of x1 for cords
USE: reads x1
*/
float read_x1( float x1 )
{
printf( "\nenter x1: " );
if ( scanf( "%f" , &x1 ) != 1 )
{
printf( "\nFailed to read entered value\n" );
x1 = 'E';
return x1;
}
return x1;
}
/* FUNTION: read_x2
INPUT: prompt user for x2
OUTPUT: returns the values of x2 for cords
USE: reads x2
*/
float read_x2( float x2 )
{
printf( "\nenter x2: " );
if ( scanf( "%f" , &x2 ) != 1 )
{
printf( "\nFailed to read entered number\n" );
x2 = 'E';
return x2;
}
return x2;
}
/* FUNTION: read_y1
INPUT: prompt user for y1
OUTPUT: returns the values of y1 for cords
USE: reads y1
*/
float read_y1( float y1 )
{
printf( "\nenter y1: " );
if ( scanf( "%f" , &y1 ) != 1 )
{
printf( "\nFailed to read entered number\n" );
y1 = 'E';
return y1;
}
return y1;
}
/* FUNTION: read_y2
INPUT: prompt user for y2
OUTPUT: returns the values of y2 for cords
USE: reads y2
*/
float read_y2( float y2 )
{
printf( "\nenter y2: " );
if ( scanf( "%f" , &y2 ) != 1 )
{
printf( "\nFailed to read entered number\n" );
y2 = 'E';
return y2;
}
return y2;
}
