It seems that this hasn't yet been documented any well, but please be aware that displayed/printed values of floating point numbers are dependent on PHP configuration "precision". You might need to keep this in mind if you are doing tests with floating point numbers and want you test scripts always work under different situations.
Following code tested with PHP 5.3.18 on a 64-bit machine:
<?php
for ($i = 15; $i < 19; $i++) {
ini_set('precision', $i);
echo sprintf('When PHP configuration "precision" is set to %2d, floating point number 1.12 is displayed as:', $i), "\n\t", 1.12, "\n\t", (string)1.12, "\n\t", round(1.12, 2), "\n";
echo "\tString ", (string)1.12, ' ((string)1.12) and ', (string)'1.12', " ((string)'1.12') are ", (string)1.12 == (string)'1.12' ? 'equal' : 'different', " when compared with '=='.\n";
// When PHP configuration 'precision' is set to different values, following expression prints different results!
echo "\tString ", (string)1.12, ' ((string)1.12) and ', (string)'1.12', " ((string)'1.12') are ", (string)1.12 === (string)'1.12' ? 'equal' : 'different', " when compared with '==='.\n";
}
?>
Output:
When PHP configuration "precision" is set to 15, floating point number 1.12 is printed as:
1.12
1.12
1.12
String 1.12 ((string)1.12) and 1.12 ((string)'1.12') are equal when compared with '=='.
String 1.12 ((string)1.12) and 1.12 ((string)'1.12') are equal when compared with '==='.
When PHP configuration "precision" is set to 16, floating point number 1.12 is printed as:
1.12
1.12
1.12
String 1.12 ((string)1.12) and 1.12 ((string)'1.12') are equal when compared with '=='.
String 1.12 ((string)1.12) and 1.12 ((string)'1.12') are equal when compared with '==='.
When PHP configuration "precision" is set to 17, floating point number 1.12 is printed as:
1.1200000000000001
1.1200000000000001
1.1200000000000001
String 1.1200000000000001 ((string)1.12) and 1.12 ((string)'1.12') are equal when compared with '=='.
String 1.1200000000000001 ((string)1.12) and 1.12 ((string)'1.12') are different when compared with '==='.
When PHP configuration "precision" is set to 18, floating point number 1.12 is printed as:
1.12000000000000011
1.12000000000000011
1.12000000000000011
String 1.12000000000000011 ((string)1.12) and 1.12 ((string)'1.12') are equal when compared with '=='.
String 1.12000000000000011 ((string)1.12) and 1.12 ((string)'1.12') are different when compared with '==='.
Números de ponto flutuante
Números de ponto flutuante (também conhecidos como "floats", "doubles" ou "números reais") podem ser especificados utilizando qualquer uma das seguintes sintaxes:
<?php
$a = 1.234;
$b = 1.2e3;
$c = 7E-10;
?>
Formalmente:
LNUM [0-9]+
DNUM ([0-9]*[\.]{LNUM}) | ({LNUM}[\.][0-9]*)
EXPONENT_DNUM [+-]?(({LNUM} | {DNUM}) [eE][+-]? {LNUM})
O tamanho de um número de ponto flutuante é dependente de plataforma, sendo o máximo de ~1.8e308 com uma precisão de 14 dígitos decimais um valor comum (número de 64 bits no formato IEEE).
Aviso
Precisão de números de ponto flutuante
Números de ponto flutuante tem precisão limitada. Embora dependa do sitema, o PHP geralmente utiliza o sistema de precisão dupla do IEEE 754, que terá uma precisão máxima devida a arredondamentos da ordem de 1.11e-16. Operações mátemáticas incomuns poderão incorrer em erros maiores, fora que a propagação de erros precisa ser considerada quando várias operações forem realizadas.
Além disso, números racionais que tem representação exata em números em base 10, como 0.1 ou 0.7, não possuem representação exata em ponto flutuante na base 2 (o formato utilizado internamente), não importanto o tamanho da mantissa. Portanto não existe conversão para o formato interno sem uma pequena perda de precisão. Isso pode ocasionar resultados confusos: por exemplo, floor((0.1+0.7)*10) normalmente retornará 7, em vez do resultado esperado 8, porque a representação interna final será algo como 7.9999999999999991118....
Então, nunca confie em resultados com números de ponto flutuante até a última casa e nunca compare números de ponto flutuante em igualdades. Se você realmente precisar de alta precisão, você pode utilizar as funções matemáticas de precisão arbitrária ou as funções relacionadas ao gmp.
Para uma explicação "simples" dessa questão, veja » o guia sobre ponto flutuante, que também tem o título alternativo de "Porque meus números não somam direito?".
Convertendo para float
Para informações sobre a conversão de strings para floats, veja a seção entitulada Conversão de Strings para números. Para valores de outros tipos, o valor é primeiro convertido para inteiro e então para float. Veja a seção Convertendo para inteiros para mais informações. No PHP 5, um aviso é emitido se você tentar converter um object para um float.
Comparando floats
Como notado acima, testar números de ponto flutuante com igualdade é probelmático, por causa da maneira como são armazenados internamente. Entretanto existem maneiras de fazer comparações com números de ponto flutuante que contornam essas limitações.
Para testar números de ponto flutuante, utilize um "valor de erro máximo" na comparação utilizada. Esse valor é também chamado de epsilon, ou erro de unidade, e deve ser a diferença máxima aceitável no resultado dos cálculos.
$a and $b serão considerados iguais até o 5º dígito de precisão.
<?php
$a = 1.23456789;
$b = 1.23456780;
$epsilon = 0.00001;
if(abs($a-$b) < $epsilon) {
echo "iguais";
}
?>
NaN
Algumas operações numéricas podem resultar em valores representados pela constante
NAN. Esse resultado representa um valor indefinido
ou não representável nos cálculos de ponto flutuante. Qualquer
comparação deste valor com qualquer outro, inclusive ele mesmo, terá
como resultado FALSE.
Como o NAN representa um resultado irrepresentável,
NAN não deve ser comparado com outros valores, incluindo
si mesmo, o correto sendo a utilização da função is_nan().
add a note
User Contributed Notes 30 notes
deminy at deminy dot net ¶
11 months ago
magicaltux at php dot net ¶
3 years ago
In some cases you may want to get the maximum value for a float without getting "INF".
var_dump(1.8e308); will usually show: float(INF)
I wrote a tiny function that will iterate in order to find the biggest non-infinite float value. It comes with a configurable multiplicator and affine values so you can share more CPU to get a more accurate estimate.
I haven't seen better values with more affine, but well, the possibility is here so if you really thing it's worth the cpu time, just try to affine more.
Best results seems to be with mul=2/affine=1. You can play with the values and see what you get. The good thing is this method will work on any system.
<?php
function float_max($mul = 2, $affine = 1) {
$max = 1; $omax = 0;
while((string)$max != 'INF') { $omax = $max; $max *= $mul; }
for($i = 0; $i < $affine; $i++) {
$pmax = 1; $max = $omax;
while((string)$max != 'INF') {
$omax = $max;
$max += $pmax;
$pmax *= $mul;
}
}
return $omax;
}
?>
www.sarioz.com ¶
10 years ago
just a comment on something the "Floating point precision" inset, which goes: "This is related to .... 0.3333333."
While the author probably knows what they are talking about, this loss of precision has nothing to do with decimal notation, it has to do with representation as a floating-point binary in a finite register, such as while 0.8 terminates in decimal, it is the repeating 0.110011001100... in binary, which is truncated. 0.1 and 0.7 are also non-terminating in binary, so they are also truncated, and the sum of these truncated numbers does not add up to the truncated binary representation of 0.8 (which is why (floor)(0.8*10) yields a different, more intuitive, result). However, since 2 is a factor of 10, any number that terminates in binary also terminates in decimal.
zelko at mojeime dot com ¶
2 years ago
<?php
$binarydata32 = pack('H*','00000000');
$float32 = unpack("f", $binarydata32); // 0.0
$binarydata64 = pack('H*','0000000000000000');
$float64 = unpack("d", $binarydata64); // 0.0
?>
I get 0 both for 32-bit and 64-bit numbers.
But, please don't use your own "functions" to "convert" from float to binary and vice versa. Looping performance in PHP is horrible. Using pack/unpack you use processor's encoding, which is always correct. In C++ you can access the same 32/64 data as either float/double or 32/64 bit integer. No "conversions".
To get binary encoding:
<?php
$float32 = pack("f", 5300231);
$binarydata32 =unpack('H*',$float32); //"0EC0A14A"
$float64 = pack("d", 5300231);
$binarydata64 =unpack('H*',$float64); //"000000C001385441"
?>
And my example from half a year ago:
<?php
$binarydata32 = pack('H*','0EC0A14A');
$float32 = unpack("f", $binarydata32); // 5300231
$binarydata64 = pack('H*','000000C001385441');
$float64 = unpack("d", $binarydata64); // 5300231
?>
And please mind the Big and Little endian boys...
james dot cridland at virginradio dot co dot uk ¶
10 years ago
The 'floating point precision' box in practice means:
<? echo (69.1-floor(69.1)); ?>
Think this'll return 0.1?
It doesn't - it returns 0.099999999999994
<? echo round((69.1-floor(69.1))); ?>
This returns 0.1 and is the workaround we use.
Note that
<? echo (4.1-floor(4.1)); ?>
*does* return 0.1 - so if you, like us, test this with low numbers, you won't, like us, understand why all of a sudden your script stops working, until you spend a lot of time, like us, debugging it.
So, that's all lovely then.
Bob ¶
4 years ago
In MySQL, many floating point number types can have a range specified using 2 values, the "precision" and the "scale" E.g. 'float(precision,scale)' for the datatype. This syntax means a number may be <precision> bits long, but may only have <scale> bits after the decimal point. E.g. a 'float(5,2)' field may have the values -999.99 to 999.99.
Here is a function to validate a PHP float using this syntax:
<?php
function validate_float($float, $precision, $scale)
{
$max = (float)str_pad("", $precision-$scale, '9').'.'.str_pad("", $scale, '9');
$min = (float)"-$max";
if(($float < $min) || ($float > $max)) return false;
else return true;
}
?>
Anonymous ¶
3 years ago
Calculations involving float types become inaccurate when it deals with numbers with more than approximately 8 digits long where ever the decimal point is. This is because of how 32bit floats are commonly stored in memory. This means if you rely on float types while working with tiny fractions or large numbers, your calculations can end up between tiny fractions to several trillion off.
This usually won't matter when converting to binary memory storage form and editing many applications' float memory addresses directly, or dealing with smaller length numbers. But if you're working with larger scale numbers and decimals, it's best to switch to working with other types: http://www.php.net/manual/en/refs.math.php
Luzian ¶
8 years ago
Be careful when using float values in strings that are used as code later, for example when generating JavaScript code or SQL statements. The float is actually formatted according to the browser's locale setting, which means that "0.23" will result in "0,23". Imagine something like this:
$x = 0.23;
$js = "var foo = doBar($x);";
print $js;
This would result in a different result for users with some locales. On most systems, this would print:
var foo = doBar(0.23);
but when for example a user from Germany arrives, it would be different:
var foo = doBar(0,23);
which is obviously a different call to the function. JavaScript won't state an error, additional arguments are discarded without notice, but the function doBar(a) would get 0 as parameter. Similar problems could arise anywhere else (SQL, any string used as code somewhere else). The problem persists, if you use the "." operator instead of evaluating the variable in the string.
So if you REALLY need to be sure to have the string correctly formatted, use number_format() to do it!
Julian L ¶
2 years ago
Convert a hex string into a 32-bit IEEE 754 float number. This function is 2 times faster then the below hex to 32bit function. This function only changes datatypes (string to int) once. Also, this function is a port from the hex to 64bit function from below.
<?php
function hexTo32Float($strHex) {
$v = hexdec($strHex);
$x = ($v & ((1 << 23) - 1)) + (1 << 23) * ($v >> 31 | 1);
$exp = ($v >> 23 & 0xFF) - 127;
return $x * pow(2, $exp - 23);
}
?>
<?php
//example
echo hexTo32Float("C4028000"); // outputs: -522
echo hexTo32Float("457F9000"); // outputs: 4089
echo hexTo32Float("2D7F5"); // outputs: 6.00804264307E-39
echo hexTo32Float("0002D7F5"); // outputs: 6.00804264307E-39
echo hexTo32Float("47D9F95E"); // outputs: 111602.734375
?>
backov at spotbrokers-nospamplz dot com ¶
10 years ago
I'd like to point out a "feature" of PHP's floating point support that isn't made clear anywhere here, and was driving me insane.
This test (where var_dump says that $a=0.1 and $b=0.1)
if ($a>=$b) echo "blah!";
Will fail in some cases due to hidden precision (standard C problem, that PHP docs make no mention of, so I assumed they had gotten rid of it). I should point out that I originally thought this was an issue with the floats being stored as strings, so I forced them to be floats and they still didn't get evaluated properly (probably 2 different problems there).
To fix, I had to do this horrible kludge (the equivelant of anyway):
if (round($a,3)>=round($b,3)) echo "blah!";
THIS works. Obviously even though var_dump says the variables are identical, and they SHOULD BE identical (started at 0.01 and added 0.001 repeatedly), they're not. There's some hidden precision there that was making me tear my hair out. Perhaps this should be added to the documentation?
kjohnson at zootweb dot com ¶
5 years ago
PHP switches from the standard decimal notation to exponential notation for certain "special" floats. You can see a partial list of such "special" values with this:
<?php
for( $tmp = 0, $i = 0; $i < 100; $i++ ) {
$tmp += 100000;
echo round($tmp),"\n";
}
?>
So, if you add two floats, end up with a "special" value, e.g. 1.2E+6, then put that value unmodified into an update query to store the value in a decimal column, say, you will likely get a failed transaction, since the database will see "1.2E+6" as varchar data, not decimal. Likewise, you will likely get an XSD validation error if you put the value into xml.
I have to be honest: this is one of the strangest things I have seen in any language in over 20 years of coding, and it is a colossal pain to work around.
helly at php dot net ¶
6 years ago
Floating point values have a limited precision. Hence a value might not have the same string representation after any processing. That also includes writing a floating point value in your script and directly printing it without any mathematical operations.
If you would like to know more about "floats" and what IEEE 754 is read this: http://docs.sun.com/source/806-3568/ncg_goldberg.html
dev at maintainfit dot com ¶
10 years ago
I was programming an accounting application in MySql that required me to sum a collection of floats and ensure that they equal zero before commiting a transaction, but as seen above a sum of floats cannot always be trusted (as was my case). I kept getting a very small remainder (like 1.4512431231e-14). Since I had used number_format(num,2) to set the precision of the numbers in the database to only two (2) decimal places, when the time comes to calculate the sum I simply multiply every number by ten (10), therby eliminating and decimal places and leaving me with integers to preform my sum. This worked great.
jack at surfacefinishtech dot com ¶
10 months ago
<?php
/** hex2float
* (Convert 8 digit hexadecimal value to float (single-precision 32bits)
* Accepts 8 digit hexadecimal values in a string
* @usage:
* hex2float32n("429241f0"); returns -> "73.128784179688"
* */
function hex2float($number) {
$binfinal = sprintf("%032b",hexdec($number));
$sign = substr($binfinal, 0, 1);
$exp = substr($binfinal, 1, 8);
$mantissa = "1".substr($binfinal, 9);
$mantissa = str_split($mantissa);
$exp = bindec($exp)-127;
$significand=0;
for ($i = 0; $i < 24; $i++) {
$significand += (1 / pow(2,$i))*$mantissa[$i];
}
return $significand * pow(2,$exp) * ($sign*-2+1);
}
?>
Bob ¶
4 years ago
Here is a function to convert an exponential-format float to a decimal-format float; e.g. 1.6e+12 to 1600000000000.
It will help addressing the problem specified by kjohnson above.
I have tested it, but not in any real world situation so any feedback/improvements/bug-reports would be appreciated.
<?php
function exp_to_dec($float_str)
// formats a floating point number string in decimal notation, supports signed floats, also supports non-standard formatting e.g. 0.2e+2 for 20
// e.g. '1.6E+6' to '1600000', '-4.566e-12' to '-0.000000000004566', '+34e+10' to '340000000000'
// Author: Bob
{
// make sure its a standard php float string (i.e. change 0.2e+2 to 20)
// php will automatically format floats decimally if they are within a certain range
$float_str = (string)((float)($float_str));
// if there is an E in the float string
if(($pos = strpos(strtolower($float_str), 'e')) !== false)
{
// get either side of the E, e.g. 1.6E+6 => exp E+6, num 1.6
$exp = substr($float_str, $pos+1);
$num = substr($float_str, 0, $pos);
// strip off num sign, if there is one, and leave it off if its + (not required)
if((($num_sign = $num[0]) === '+') || ($num_sign === '-')) $num = substr($num, 1);
else $num_sign = '';
if($num_sign === '+') $num_sign = '';
// strip off exponential sign ('+' or '-' as in 'E+6') if there is one, otherwise throw error, e.g. E+6 => '+'
if((($exp_sign = $exp[0]) === '+') || ($exp_sign === '-')) $exp = substr($exp, 1);
else trigger_error("Could not convert exponential notation to decimal notation: invalid float string '$float_str'", E_USER_ERROR);
// get the number of decimal places to the right of the decimal point (or 0 if there is no dec point), e.g., 1.6 => 1
$right_dec_places = (($dec_pos = strpos($num, '.')) === false) ? 0 : strlen(substr($num, $dec_pos+1));
// get the number of decimal places to the left of the decimal point (or the length of the entire num if there is no dec point), e.g. 1.6 => 1
$left_dec_places = ($dec_pos === false) ? strlen($num) : strlen(substr($num, 0, $dec_pos));
// work out number of zeros from exp, exp sign and dec places, e.g. exp 6, exp sign +, dec places 1 => num zeros 5
if($exp_sign === '+') $num_zeros = $exp - $right_dec_places;
else $num_zeros = $exp - $left_dec_places;
// build a string with $num_zeros zeros, e.g. '0' 5 times => '00000'
$zeros = str_pad('', $num_zeros, '0');
// strip decimal from num, e.g. 1.6 => 16
if($dec_pos !== false) $num = str_replace('.', '', $num);
// if positive exponent, return like 1600000
if($exp_sign === '+') return $num_sign.$num.$zeros;
// if negative exponent, return like 0.0000016
else return $num_sign.'0.'.$zeros.$num;
}
// otherwise, assume already in decimal notation and return
else return $float_str;
}
?>
rick at ninjafoo dot com ¶
8 years ago
Concider the following:
(19.6*100) != 1960
echo gettype(19.6*100) returns 'double', However even .....
(19.6*100) !== (double)1960
19.6*100 cannot be compaired to anything without manually
casting it as something else first.
(string)(19.6*100) == 1960
Rule of thumb, if it has a decimal point, use the BCMath functions.
feline at NOSPAM dot penguin dot servehttp dot com ¶
9 years ago
General computing hint: If you're keeping track of money, do yourself and your users the favor of handling everything internally in cents and do as much math as you can in integers. Store values in cents if at all possible. Add and subtract in cents. At every operation that wii involve floats, ask yourself "what will happen in the real world if I get a fraction of a cent here" and if the answer is that this operation will generate a transaction in integer cents, do not try to carry fictional fractional accuracy that will only screw things up later.
davidszilardd at gmail dot com ¶
1 year ago
The function returns 5 for 5,000 because if there is no decimal point, then the first strpos will be FALSE, and FALSE < 1 is TRUE so the condition will be still true.
It should be checked whether strpos returns a valid position:
<?php
function str2num($str)
{
if (strpos($str, '.') !== FALSE && strpos($str, ',') !== FALSE && strpos($str, '.') < strpos($str,','))
{
$str = str_replace('.','',$str);
$str = strtr($str,',','.');
}
else
{
$str = str_replace(',','',$str);
}
return (float)$str;
}
?>
m dot lebkowski+php at gmail dot com ¶
5 years ago
Just another note about the locales. Consider the following code:
<?php
// in polish locale decimal separator is ","
setlocale(LC_ALL, "pl_PL");
$a = 5/2;
echo (float)(string)$a;
/// prints "2", so the decimal part is dropped
?>
This causes very serious problems in my opinion. In some locale combination the typecasting can be destructive.
Maybe when locale decimal separator is ",", then (float)"2,5" should be recognized as "two and a half"?
Anyway - bare that in mind and be very careful when casting floats to strings and back.
zelko at mojeime dot com ¶
3 years ago
The was talk about "converting" 32 and 64 bit IEEE754 binary numbers to PHP float. The issue isn't as much converting, since they are already in binary form, as it is casting. PHP doesn't allow direct accessing of memory, but you can still get around a bit.
The right was to read floats (32 and 64 bit) is this:
<?php
$binarydata32 = pack('H*','0EC0A14A');
$float32 = unpack("f", $binarydata32);
$binarydata64 = pack('H*','000000C001385441');
$float64 = unpack("d", $binarydata64);
var_dump($float32,$float64,$float32==$float64);
?>
The result of dump():
<?php
array(1) {
[1]=>
float(5300231)
}
array(1) {
[1]=>
float(5300231)
}
bool(true)
?>
Note: mind the Big and Little endian boys
pgarvin76+phpmanual at gmail dot com ¶
3 years ago
When converting from float to string trailing zeros will be dropped. Consider the following example. Tested on PHP 5.3.1.
<?php
$a = 5.00500;
$b = 30.00;
echo "a = $a\n";
echo "b = $b\n";
/* outputs:
a = 5.005
b = 30
*/
?>
inforsci at gmail dot com ¶
3 years ago
convert 32bit HEX values into IEEE 754 floating point
<?php
$strHex = "C45F82ED";
$bin = str_pad(base_convert($strHex, 16, 2), 32, "0", STR_PAD_LEFT);
$sign = $bin[0];
$exp = bindec(substr($bin, 1, 8)) - 127;
$man = (2 << 22) + bindec(substr($bin, 9, 23));
$dec = $man * pow(2, $exp - 23) * ($sign ? -1 : 1);
echo "Answer = " . $dec . "<BR>\n";
?>
pcunha at gmail dot com ¶
1 year ago
To simply convert 32 bits float from hex to float:
<?php
function hexfloat ($hex){
return (unpack("f", pack('H*',$hex))[1]);
}
?>
This may be useful for arduino interface with php.
rob at willo dot org ¶
4 years ago
PHP will parse ".123" with no leading digit; just a decimal point. For a command-line example:
php -r "echo 1 + .123;"
The regular expression provided above does not parse it.
My correction is:
EXPONENT_DNUM = "[+-]?({DNUM} | ({LNUM} | {DNUM}) [eE][+-]? {LNUM})"
NOTE: {LNUM} by itself is an integer, not a floating point.
info at forrest79 dot net ¶
4 years ago
My BIN to FLOAT (IEEE754), the first one doesn't work for me:
<?php
function binToFloat($bin) {
if(strlen($bin) > 32) {
return false;
} else if(strlen($bin) < 32) {
$bin = str_repeat('0', (32 - strlen($bin))) . $bin;
}
$sign = 1;
if(intval($bin[0]) == 1) {
$sign = -1;
}
$binExponent = substr($bin, 1, 8);
$exponent = -127;
for($i = 0; $i < 8; $i++) {
$exponent += (intval($binExponent[7 - $i]) * pow(2, $i));
}
$binBase = substr($bin, 9);
$base = 1.0;
for($x = 0; $x < 23; $x++) {
$base += (intval($binBase[$x]) * pow(0.5, ($x + 1)));
}
$float = (float) $sign * pow(2, $exponent) * $base;
return $float;
}
?>
manasseh at smartcomputerinc.com ¶
2 years ago
I found that 00000000 hex was converting to 1.0 decimal. From the Wikipedia article on IEEE-754 floating point:
The true significand includes 23 fraction bits to the right of the binary point and an implicit leading bit (to the left of the binary point) with value 1 unless the exponent is stored with all zeros.
In hex2float32n, replace:
$intnumber=bindec("1".$binint);
with
if ($exp <> -127)
{ $intnumber=bindec("1".$binint); };
and then 00000000 works correctly without affecting "normal" numbers.
TRI0N ¶
8 years ago
Here is a simple formula to break down a number and get rid of the decimal values. I built this to take a number in seconds and convert it to a readable value for Server Uptimes.
<?php
$day = floor(($uptime / 86400)*1.0) ;
$calc1 = $day * 86400 ;
$calc2 = $uptime - $calc1 ;
$hour = floor(($calc2 / 3600)*1.0) ;
if ($hour < 10) {
$hour = "0".$hour ;
}
$calc3 = $hour * 3600 ;
$calc4 = $calc2 - $calc3 ;
$min = floor(($calc4 / 60)*1.0) ;
if ($min < 10) {
$min = "0".$min ;
}
$calc5 = $min * 60 ;
$sec = floor(($calc4 - $calc5)*1.0) ;
if ($min < 10) {
$sec = "0".$sec ;
}
$uptime2 = $day." Days, ".$hour.":".$min.":".$sec ;
?>
Place this where you want the results to be seen:
<?php echo $uptime2 ; ?>
For a Value of 1455587 seconds the results will show as followed:
16 Days, 20:19:47
Enjoy
reinaldorock at yahoo dot com dot br ¶
2 years ago
Convert locale string into float number
<?php
function str2num($str){
if(strpos($str, '.') < strpos($str,',')){
$str = str_replace('.','',$str);
$str = strtr($str,',','.');
}
else{
$str = str_replace(',','',$str);
}
return (float)$str;
}
str2num('25,01'); //25.01
str2num('2.5,01'); //25.01
str2num('25.01'); //25.01
str2num('2,5.01'); //25.01
?>
francois dot barbier at gmail dot com ¶
4 years ago
As "m dot lebkowski+php at gmail dot com" (http://www.php.net/language.types.float#81416) noted 9 comments below :
When PHP converts a float to a string, the decimal separator used depends on the current locale conventions.
However, to declare a floating point number, one must always use a full stop otherwhise the code would be locale dependent (imagine the nightmare):
<?php
$float = 1.5; // float(1.5)
$float = 1,5; // Parse error: syntax error, unexpected ','
$float = (float) '1.5'; // float(1.5)
$float = (float) '1,5'; // float(1)
?>
Now, if you have a string containing a localized number, you can convert it back to a floating point number using the following function:
<?php
/**
* Convert a localized number string into a floating point number
*
* @param string $sNumber The localized number string to convert.
* @return float The converted number.
*/
function str2num($sNumber)
{
$aConventions = localeConv();
$sNumber = trim((string) $sNumber);
$bIsNegative = (0 === $aConventions['n_sign_posn'] && '(' === $sNumber{0} && ')' === $sNumber{strlen($sNumber) - 1});
$sCharacters = $aConventions['decimal_point'].
$aConventions['mon_decimal_point'].
$aConventions['negative_sign'];
$sNumber = preg_replace('/[^'.preg_quote($sCharacters).'\d]+/', '', trim((string) $sNumber));
$iLength = strlen($sNumber);
if (strlen($aConventions['decimal_point']))
{
$sNumber = str_replace($aConventions['decimal_point'], '.', $sNumber);
}
if (strlen($aConventions['mon_decimal_point']))
{
$sNumber = str_replace($aConventions['mon_decimal_point'], '.', $sNumber);
}
$sNegativeSign = $aConventions['negative_sign'];
if (strlen($sNegativeSign) && 0 !== $aConventions['n_sign_posn'])
{
$bIsNegative = ($sNegativeSign === $sNumber{0} || $sNegativeSign === $sNumber{$iLength - 1});
if ($bIsNegative)
{
$sNumber = str_replace($aConventions['negative_sign'], '', $sNumber);
}
}
$fNumber = (float) $sNumber;
if ($bIsNegative)
{
$fNumber = -$fNumber;
}
return $fNumber;
}
?>
Example:
<?php
setLocale(LC_ALL, 'fr_BE.UTF-8'); // decimal separator is now a comma
$float = -123456.789;
$string = (string) $float;
var_dump($float); // float(-123456,789)
var_dump($string); // string(11) "-123456,789"
var_dump((float) $string); // float(-123456)
var_dump(str2num($string)); // float(-123456,789)
?>
It also works with strings returned by the number_format() function:
<?php
setLocale(LC_ALL, 'fr_BE.UTF-8'); // decimal separator is now a comma
$conv = localeconv();
$float = -123456.789;
$string = $conv['int_curr_symbol'].number_format($float, $conv['frac_digits'], $conv['decimal_point'], $conv['thousands_sep']);
var_dump($float); // float(-123456,789)
var_dump($string); // string(15) "EUR -123.456,79"
var_dump((float) $string); // float(0)
var_dump(str2num($string)); // float(-123456,79)
?>
catalin dot luntraru at gmail dot com ¶
16 days ago
$x = 8 - 6.4; // which is equal to 1.6
$y = 1.6;
var_dump($x == $y); // is not true
PHP thinks that 1.6 (coming from a difference) is not equal to 1.6. To make it work, use round()
var_dump(round($x, 2) == round($y, 2)); // this is true
This happens probably because $x is not really 1.6, but 1.599999.. and var_dump shows it to you as being 1.6.