bindec
(PHP 4, PHP 5, PHP 7)
bindec — Binary to decimal
Description
number bindec ( string $binary_string ) Returns the decimal equivalent of the binary number represented by the binary_string argument.
bindec() converts a binary number to an integer or, if needed for size reasons, float.
bindec() interprets all binary_string values as unsigned integers. This is because bindec() sees the most significant bit as another order of magnitude rather than as the sign bit.
Parameters
binary_string
The binary string to convert
Warning
The parameter must be a string. Using other data types will produce unexpected results.
Return Values
The decimal value of binary_string
Examples
Example #1 bindec() example
<?php
echo?bindec('110011')?.?"\n";
echo?bindec('000110011')?.?"\n";
echo?bindec('111');
?>The above example will output:
51
51
7Example #2 bindec() interprets input as unsigned integers
<?php
/*
?*?The?lesson?from?this?example?is?in?the?output
?*?rather?than?the?PHP?code?itself.
?*/
$magnitude_lower?=?pow(2,?(PHP_INT_SIZE?*?8)?-?2);
p($magnitude_lower?-?1);
p($magnitude_lower,?'See?the?rollover???Watch?it?next?time?around...');
p(PHP_INT_MAX,?'PHP_INT_MAX');
p(~PHP_INT_MAX,?'interpreted?to?be?one?more?than?PHP_INT_MAX');
if?(PHP_INT_SIZE?==?4)?{
????$note?=?'interpreted?to?be?the?largest?unsigned?integer';
}?else?{
????$note?=?'interpreted?to?be?the?largest?unsigned?integer
??????????????(18446744073709551615)?but?skewed?by?float?precision';
}
p(-1,?$note);
function?p($input,?$note?=?'')?{
????echo?"input:????????$input\n";
????$format?=?'%0'?.?(PHP_INT_SIZE?*?8)?.?'b';
????$bin?=?sprintf($format,?$input);
????echo?"binary:???????$bin\n";
????ini_set('precision',?20);??//?For?readability?on?64?bit?boxes.
????$dec?=?bindec($bin);
????echo?'bindec():?????'?.?$dec?.?"\n";
????if?($note)?{
????????echo?"NOTE:?????????$note\n";
????}
????echo?"\n";
}
?>Output of the above example on 32 bit machines:
input: 1073741823
binary: 00111111111111111111111111111111
bindec(): 1073741823
input: 1073741824
binary: 01000000000000000000000000000000
bindec(): 1073741824
NOTE: See the rollover? Watch it next time around...
input: 2147483647
binary: 01111111111111111111111111111111
bindec(): 2147483647
NOTE: PHP_INT_MAX
input: -2147483648
binary: 10000000000000000000000000000000
bindec(): 2147483648
NOTE: interpreted to be one more than PHP_INT_MAX
input: -1
binary: 11111111111111111111111111111111
bindec(): 4294967295
NOTE: interpreted to be the largest unsigned integerOutput of the above example on 64 bit machines:
input: 4611686018427387903
binary: 0011111111111111111111111111111111111111111111111111111111111111
bindec(): 4611686018427387903
input: 4611686018427387904
binary: 0100000000000000000000000000000000000000000000000000000000000000
bindec(): 4611686018427387904
NOTE: See the rollover? Watch it next time around...
input: 9223372036854775807
binary: 0111111111111111111111111111111111111111111111111111111111111111
bindec(): 9223372036854775807
NOTE: PHP_INT_MAX
input: -9223372036854775808
binary: 1000000000000000000000000000000000000000000000000000000000000000
bindec(): 9223372036854775808
NOTE: interpreted to be one more than PHP_INT_MAX
input: -1
binary: 1111111111111111111111111111111111111111111111111111111111111111
bindec(): 18446744073709551616
NOTE: interpreted to be the largest unsigned integer
(18446744073709551615) but skewed by float precisionNotes
Note: The function can convert numbers that are too large to fit into the platforms integer type, larger values are returned as float in that case.
See Also
- decbin() - Decimal to binary
- octdec() - Octal to decimal
- hexdec() - Hexadecimal to decimal
- base_convert() - Convert a number between arbitrary bases
← base_convert
ceil →
? 1997–2017 The PHP Documentation GroupLicensed under the Creative Commons Attribution License v3.0 or later.
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