Problem with 'float' data type

[iflash]

Hi,

I am learning C and i had to write a program for an exercise. However i tried many ways but still couldn't get the result to be correct. I found out the it's a problem with float numbers. Here is the code i wrote, PLS help me to get it to work, it's probably only a small silly mistake of mine but i just can't get it out.

thnx in advance

--------------------------------------------------------------------------------

/* Calculate miles / gallon obtained for each tank. */

#include <stdio.h>

int main()
{
int miles = 0, totalMiles, gallons = 0, totalGallons;
float overallAverage, temp;

printf( "Enter the gallons used (-1 to end): " );
scanf( "%d", &gallons);
printf( "Enter the miles driven: " );
scanf( "%d", &miles );

while ( gallons != -1) {
totalMiles += miles;
totalGallons += gallons;

if ( miles != 0 )
if ( gallons != 0 ) {
temp = ( float ) miles / gallons;
printf( "The miles / gallon for this tank was %.2f \n\n", temp);
}

printf( "Enter the gallons used (-1 to end): " );
scanf( "%d", &gallons);
if ( gallons != -1 ) {
printf( "Enter the miles driven: " );
scanf( "%d", &miles);
}

}

overallAverage = ( float ) totalMiles / totalGallons;
printf( "\nTHe overall average miles/gallon was %.2f", overallAverage );

return 0;

}

------------------------------------------------------------------------------------

I've also uploaded the output (incorrect) of this program.

thanx

[khinlau]

You need to add 2 more lines to your program before While stement. like this:
.
.
.
totalMiles =0;
totalGallons =0;
while ( gallons != -1){
.
.
.


Or you can init that 2 variables when you declare them.

Let free now!

[iflash]

actually, it was my mistake, my stupid compiler doesn't support the float data type, i switched to working with borland c compiler. BUt now i had another problem with loops , it's posted just above this thread.

[khinlau]

Actually I don't know what your problem, Can you tell more about that?

[iflash]

i just wanna konw what's wrong with that piece of code and how to get it to work without being trapped in the loop.

thnx

[MoMad]

Try changing your code to:

#include <stdio.h> 

int main() 
{ 
    int miles =0, totalMiles =0, gallons =0, totalGallons =0; 
    float overallAverage =0, temp =0;

    do {
        printf( "Enter the gallons used (-1 to end): " ); 
        scanf( "%d", &gallons); 
        printf( "Enter the miles driven: " ); 
        scanf( "%d", &miles ); 

        totalMiles += miles; 
        totalGallons += gallons; 

        if ( miles != 0 && gallons != 0 ) { 
            temp = ( float ) miles / gallons; 
            printf( "The miles / gallon for this tank was %.2f \n\n", temp); 
        } 
    } while( gallons != -1 );

    overallAverage = ( float ) totalMiles / totalGallons; 
    printf( "\nTHe overall average miles/gallon was %.2f", overallAverage ); 

    return 0; 
} 

Floats are Standard C/C++ datatypes so I dont see why a compiler will not support them. Thats a bunch of crap I tell you. Anyways, the only float bug I know of is:

float x = 3F, y = 3.0F;
printf("X/Y = %f\n", (float) x / y );
// Might not output 1 because of rounding errors 

-MoMad