floats and printf()

[Pere Riu]

HI,

I am using printf so display floating point numbers in a LCD:

printf(lcd_putc,"\%05.2f",myfloat);

but I never get leading "0" or leading white spaces to fill up the requested 5 characters. i.e. if the number is 5.32 I get
"5.32" instead of "005.32" or " 5.32".
Any ideas ?.

Pere
___________________________
This message was ported from CCS's old forum
Original Post ID: 8292

[nilsener]

Dear,

suggestion:

1. convert the float to a string

sprintf(string, "\%5.2f", myfloat); //convert float to string

// string should be '5.32'

2. find the position of '.' in the string

ptr = &string[0]; //set pointer to beginning of string

ptr1 = strchr(string,'.'); //find '.' in string
k = ptr1 - ptr; //calculate absolute position of '.'

// k should be 1 in this case;

3. build a second string with the leading zeros

if (k == 1) strcpy(string2,"0000");
if (k == 2) strcpy(string2,"000");
if (k == 3) strcpy(string2,"00");
...
...

3. concatenate string ('5.32') onto string2 ('0000')

strcat (string2, string);

now string2 should contain '00005.32'

printf(lcd_putc,string2);

Maybe it works ?

regards nilsener


:=HI,
:=
:=I am using printf so display floating point numbers in a LCD:
:=
:=printf(lcd_putc,"\%05.2f",myfloat);
:=
:=but I never get leading "0" or leading white spaces to fill up the requested 5 characters. i.e. if the number is 5.32 I get
:="5.32" instead of "005.32" or " 5.32".
:=Any ideas ?.
:=
:=Pere
___________________________
This message was ported from CCS's old forum
Original Post ID: 8305

[pere riu]

Thanks ! That's what I am doing right now. Simply I was expecting something more clever from the compiler side.

Pere

:=Dear,
:=
:=suggestion:
:=
:=1. convert the float to a string
:=
:=sprintf(string, "\%5.2f", myfloat); //convert float to string
:=
:= // string should be '5.32'
:=
:=2. find the position of '.' in the string
:=
:=ptr = &string[0]; //set pointer to beginning of string
:=
:=ptr1 = strchr(string,'.'); //find '.' in string
:=k = ptr1 - ptr; //calculate absolute position of '.'
:=
:= // k should be 1 in this case;
:=
:=3. build a second string with the leading zeros
:=
:=if (k == 1) strcpy(string2,"0000");
:=if (k == 2) strcpy(string2,"000");
:=if (k == 3) strcpy(string2,"00");
:=...
:=...
:=
:=3. concatenate string ('5.32') onto string2 ('0000')
:=
:=strcat (string2, string);
:=
:=now string2 should contain '00005.32'
:=
:=printf(lcd_putc,string2);
:=
:=Maybe it works ?
:=
:=regards nilsener
:=
:=
:=:=HI,
:=:=
:=:=I am using printf so display floating point numbers in a LCD:
:=:=
:=:=printf(lcd_putc,"\%05.2f",myfloat);
:=:=
:=:=but I never get leading "0" or leading white spaces to fill up the requested 5 characters. i.e. if the number is 5.32 I get
:=:="5.32" instead of "005.32" or " 5.32".
:=:=Any ideas ?.
:=:=
:=:=Pere
___________________________
This message was ported from CCS's old forum
Original Post ID: 8316

[PaulF]

[Ttelmah]

The 'reason', is that the field length being specified is too short for the required leading zeros to be displayed.
In C, the field length (the bit on the left of the decimal), is for the _entire_ output field. This includes the decimal point, the trailing digits, and the leading location for the sign. To display three digits in front of the decimal, with two digits after, you would need to use a field specifier of %07.2f.

Best Wishes