Thread: Ok I'm stuck with a double to float error

  1. #1
    Registered User
    Join Date
    May 2004

    Ok I'm stuck with a double to float error

    Here's the snippet of code that I'm having problems with:

                    int            customernumber;
    	float	waterlevel;
    	float	previouslevel;
    	float	totalwater;
    	float	totalbill;
    	float	amountowed;
    	printf("Enter customer number\n" );
    	scanf( "%d" ,  &customernumber );
    	printf("Enter current water level\n" );
    	scanf("%f" , &waterlevel );
    	printf("Enter previous water level\n" );
    	scanf("%f", &previouslevel );
    	totalwater = waterlevel - previouslevel;
    	totalbill = 30 + (totalwater/1000  * .55);
    	amountowed = totalbill;
    I keep getting this warning "conversion from double to float, possible loss of data" for this line

    totalbill = 30 + (totalwater/1000 * .55);

    I dont understand what it could mean, everything is declared as float ( I, obviously, made sure of that), if anyone has any idea what's wrong with this line I would really appreciate it if ya could share it with me.
    Thank you very much.
    Last edited by Extropian; 06-06-2005 at 11:24 AM.

  2. #2
    and the hat of int overfl Salem's Avatar
    Join Date
    Aug 2001
    The edge of the known universe
    .55 by itself is a double constant.
    Since the rest of the expression is float, I think it's this one which making the whole of the right hand side into a double expression.

    So when you perform the assignment, the now double expression on the right is being converted to a float.

    .55F is the way to define a float constant.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.

  3. #3
    Frequently Quite Prolix dwks's Avatar
    Join Date
    Apr 2005
    Or you could just add a cast:

    totalbill = (float) (30 + (totalwater/1000 * .55));
    Or maybe declare everything as double and not as float.

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