[prog] Learning C Question

[Gretchen Dziengel]

I'm starting to work my way through a C book I picked up a while ago.
One of the first programs I'm working on is of course giving me
trouble.

 printf( "Enter hours for customer one.\n" );
 scanf( "%lf\n", &hours1 );
 printf( "Enter hours for customer two.\n" );
 scanf( "%lf\n", &hours2 );
 printf( "Enter hours for customer three.\n" );
 scanf( "%lf\n", &hours3 );

The first scanf wants me to put in two lines.  Everything is then
offset by one.  The second value I put in for hours1 turns into hours2
and the value for hours2 is stored as hours3.  Whatever I put in for
hrours3 is gone.

I've quoted the entire program below because I've compared those lines
several thousand times and just don't get if they are different.
Also, I know this program could be much more effective with an array,
but I'm not quite there yet.

Thanks!

Gretchen



I compile with
gcc -g -lm -o 5-09 ex5-09.c

/****************************************
Exercise 5.9 Page 187
A parking garage charges a $2.00 minimum fee to park for up to three
hours.  The garage charges an additional $0.50 per hour for each hour
or part thereof in excess of three hours.  The maximum charge for any
given 24-hour period is $10.00.  Assume that no car parks for longer
than 24 hours at a time.  Write a program that will calculate and
print the parking charges for each of 3 customers who parked their
cars in this garage yesterday.  You should enter the hours parked for
each customer.  Your program should print the results in a neat
tabular format, and should calculate and print the total of
yesterday's receipts.  The program should use the function
calculateCharges to determine the charge for each customer.
****************************************/
#include <stdio.h>
#include <math.h>

double calculateCharges( double );


int main ()
{
 double hours1 = 0, hours2 = 0, hours3 = 0;
 double charges1 = 0, charges2 = 0, charges3 = 0;

 printf( "Enter hours for customer one.\n" );
 scanf( "%lf\n", &hours1 );
 printf( "Enter hours for customer two.\n" );
 scanf( "%lf\n", &hours2 );
 printf( "Enter hours for customer three.\n" );
 scanf( "%lf\n", &hours3 );

 charges1 = calculateCharges( hours1 );
 charges2 = calculateCharges( hours2 );
 charges3 = calculateCharges( hours3 );

 printf( "Car\tHours\tCharges\n" );
 printf( "1 \t %.1f \t %.2f \n", hours1, charges1 );
 printf( "2 \t %.1f \t %.2f \n", hours2, charges2 );
 printf( "3 \t %.1f \t %.2f \n", hours3, charges3 );

 return 0;
}

double calculateCharges( double hours )
{
 double charge = 0;
 double totCharge = 0;

 if ( hours <= 3 )
   charge = 2;

 if ( hours > 3 )
   charge = 2.5;

 totCharge = floor(hours) * charge;

 if (totCharge > 10)
   totCharge = 10;

 return totCharge;
}