Thread: reading float from file

Trouble reading float variables.
I tried reading some float variables from a file. This is what happened.
Input.(input file).

Code:

Hydrogen	H	G	1	1.008
Helium		He	G	2	4.0
Lithium		Li	S	3	6.94
Beryllium	Be	S	4	9.01
Boron		B	S	5	10.8
Carbon		C	S	6	12.0
Nitrogen	N	G	7	14.0
Oxygen		O	G	8	16.0
Fluorine	F	G	9	19.0
Neon		Ne	G	10	20.2
Sodium		Na	S	11	23.0
Magnesium	Mg	S	12	24.30
Aluminium	Al	S	13	27.0

But output.(both screen and output file).

Code:

       Hydrogen		H	1	1.008	G
         Helium		He	2	4	G
        Lithium		Li	3	6.94	S
      Beryllium		Be	4	9.01	S
          Boron		B	5	10.8	S	//works ok
         Carbon		C	6	12	S
       Nitrogen		N	7	14	G
         Oxygen		O	8	16	G
       Fluorine		F	9	19	G
           Neon		Ne	10	20.200001	G //decimals.
         Sodium		Na	11	23	S
      Magnesium		Mg	12	24.299999	S //decimals
      Aluminium		Al	13	27	S

My doubt...
Is there any way to avoid this.?
I even tried editing the file as:

Code:

Neon		Ne	G	10	20.20
and
Neon		Ne	G	10	20.20000000000

here's the part reading the file...

Code:

Element table[20]; class with details of an element...
int n=0;
char na[25], sy[3], st='\0';	//name symbol and state of element...
unsigned int z=0;
float m=0.0;
while(!file.eof()){
	file>>na>>sy>>st>>z>>m;
		if(file.good()){
		table[n].set(na, sy, st, z, m);	//tested - OK
		n++;
		}
	}
cout<<"There are currently "<<n<<" entries in the input file...\n\n";

a side note:

my guess is your getting some werid output
at the end of the file to, or dealing with it in your
table, its comming from using .eof()

>float m=0.0;
Doubles will give you more precise values:
double m=0.0;

Thanks 'swoopy'...
Double worked...
I didn't know that 'float' variables had such a problem.

Thanks for the document.
but It'll take years for me to read through it.(literally!).

while(!eof) is incorrrect since eof is signaled after the final read. The correct idiom is while(read_successful).