[prog] Learning C Question

[jcv]

with apologies to Gretchen who will get this twice - I have a new 
mailer, and didn't notice I wasn't replying to the list.

jcv wrote:
 > Gretchen -
 > Will you accept help from another wanna-be-programmer?
 >
 > I haven't coded in years, but on this cold Sunday morning, your example
 > looked like it was about my level ...
 >
 > If you take out all the "\n"s in your "scanf"s, the code works (although
 > your calculate charges doesn't print the costs I would expect from the
 > description of the problem).
 >
 > I don't have a C book around, though, and I get all the languages
 > confused - is scanf supposed to read to the end of the line, or just
 > take the first thing it finds?
 >
 > Maybe the fact that I can't explain it will help you find the answer - I
 > know that works for me sometimes!
 >
 > Good luck, and thanks for inspiring me. I have two days off work, and I
 > might actually pick up a book ....
 >
 > Jeannette
 >
 > Gretchen Dziengel wrote:
 >
 >> 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;
 >> }
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 >
 >