Preventing scientific notation in a string

[NotionCommotion]

How can I perform the following?  I expect sprintf might be related, but not sure how to make it flexible for numbers of different sizes.  Thanks

$const1=0.00000000000123;
$const2=1234123124123;

$string="some text $const1 more text $const2 more text;

echo($string);  //Desired: "some text 0.00000000000123 more text 1234123124123 more text;

[requinix]

Use sprintf to get a different string representation for $const1.

$const1string = rtrim(sprintf("%.20f", $const1), "0");

[NotionCommotion]

Thanks requnix,  What about the ensuring that large numbers are not displayed in scientific notation? 

function returnNumberString($n, $min=20, $max=20){
    if(!is_numeric($n)) throw new Exception('Must be a number');
    $abs=abs($n);
    if(!$abs || $abs>1E-4 && $abs<1E4) {
        echo('just right (what should the "safe" bounds be?)'.PHP_EOL);
    }
    elseif($abs<1) {
        if($abs<pow(10,-$min)) throw new Exception("Must be greater than ".pow(10,-$min));
        echo('display small'.PHP_EOL);
        $n=rtrim(sprintf("%.{$min}F", $n), "0");
    }
    else {
        //What is the maximum size
        if($abs>pow(10,$max)) throw new Exception("Must be less than ".pow(10,$max));
        echo('display large'.PHP_EOL);
        $n=rtrim(rtrim(sprintf("%.{$max}F", $n), "0"),'.');
    }
    return $n;
}
function t($n) {
    echo"Value: $n".PHP_EOL;
    try{
        $n=returnNumberString($n);
        echo"some text $n more text".PHP_EOL;
    }
    catch(Exception $e) {
        echo $e->getMessage().PHP_EOL;
    }
}
t(1.23E-2);
t(1.23E-6);
t(1.23E-10);
t(1.23E-18);
t(1.23E-28);
t(1.23E2);
t(1.23E6);
t(1.23E19);
t(1.23E40);
t(0);

[requinix]

Value: 0.0123

just right (what should the "safe" bounds be?)

some text 0.0123 more text

Value: 1.23E-6

display small

some text 0.00000123 more text

Value: 1.23E-10

display small

some text 0.000000000123 more text

Value: 1.23E-18

display small

some text 0.00000000000000000123 more text

Value: 1.23E-28

Must be greater than 1.0E-20

Value: 123

just right (what should the "safe" bounds be?)

some text 123 more text

Value: 1230000

display large

some text 1230000 more text

Value: 1.23E+19

display large

some text 12300000000000000000 more text

Value: 1.23E+40

Must be less than 1.0E+20

Value: 0

just right (what should the "safe" bounds be?)

some text 0 more text

All the "some text" outputs aren't using scientific notation. What are you talking about?

[NotionCommotion]

Sorry, I had included more in the previous post, but must have accidentally deleted it.  Get quirky results sometimes such as when using the following due to float rounding errors.

t(1234567.86543); //outputs some text 1234567.86543000000528991222 more text

I guess if greater than 1, I can cast it to an integer, use strlen to get the number of digits, subtract that from the number of formatted decimals, remove trailing zeros, and then remove a trailing period (if applicable).  Just seems, however, that there should be a more straightforward way to do this.

 

 

Regarding these lines, any recommendation what the bounds should be so that PHP will never use scientific notation if concatenated to a string?  Will that change if the value is positive or negative?  If it does change, I suppose I could perform the operations using the absolute values and then manually add a minus sign.  Again, a bit of a kludge.

if(!$abs || $abs>1E-4 && $abs<1E4) {
        echo('just right (what should the "safe" bounds be?)'.PHP_EOL);
}

PS.  Purpose is to dynamically generate SQL type queries for a specialty database which doesn't allow SELECT someField * 3.39472E-6 AS alias FROM ....

 

[requinix]

That's your standard floating-point error. round() to a number of decimal places you know you'll never need to go beyond.

 

But are you sure scientific notation isn't allowed? MySQL, SQL Server, and PostgreSQL all do.

[NotionCommotion]

I'm not positive, but I couldn't find any documentation stating that I could and posted a question but haven't had any replies.  https://community.influxdata.com/t/how-to-use-scientific-notation-in-a-select-query-mathematical-operator/4743

 

Off topic for PHP, but can you confirm that my previous example (duplicated below) is correct for MySQL?  Couldn't find much on the subject, however, https://dev.mysql.com/doc/refman/5.6/en/number-literals.html  suggests I am doing it correct.  Most other things I read were just people asking how to disable presenting output such format.  Thanks

SELECT someField * 3.39472E-6 AS alias FROM ....

[requinix]

https://docs.influxdata.com/influxdb/v1.5/query_language/spec/#literals

Floats

InfluxQL supports floating-point literals. Exponents are not currently supported.

 

float_lit = int_lit "." int_lit .

And I wouldn't worry about floating-point errors. It's all equally imprecise in the end.

 

I don't have a MySQL console in front of me, but yes that query would be perfectly fine.