Preventing scientific notation in a string

Go to solution Solved by requinix,

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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;```
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• Solution

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

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

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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.

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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 ....`
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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.

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