How to avoid rounding off the float value when called from sqlite

Question

I am using the following statement to get a float value from table:

NSNumber *f = [NSNumber numberWithDouble:(double)sqlite3_column_double(statement, 0)];

The value in the database is 23.679999999 but I am getting 23.68. I tried numberWithFloat but i got the same result. Can anyone tell me how to get the value without rounding off?

http://stackoverflow.com/questions/5024913/comparing-float-and-double-data-types-in-objective-c — Vlad Z., Feb 14 '15 at 02:28
Get the field as text and see what it really is. (You can use the command line `sqlite3` command to do this.) Then convert that text value to double and see what you get. And keep in mind that if you print a double with `%f` you get a rounded value. — Hot Licks, Feb 14 '15 at 02:31

score 1 · Accepted Answer · answered Feb 14 '15 at 03:55

NSNumber-wrapped-double is not a suitable data type for storing decimal values when all digits must be preserved exactly. Use NSDecimalNumber instead:

unsigned char *c = sqlite3_column_text(statement, 0);
NSNumber *f = nil;
if (c) {
    NSString *numStr = [NSString stringWithUTF8String:c];
    f = [NSDecimalNumber decimalNumberWithString:numStr];
}

This should preserve all significant digits available in your text representation, as long as you use the native value. Converting to float or double may result in rounding due to differences in representation.

How to avoid rounding off the float value when called from sqlite

1 Answers1