decbin()

(PHP 4, PHP 5, PHP 7)

十进制转换为二进制

说明

返回一字符串，包含有给定$number参数的二进制表示。所能转换的最大数值为十进制的 4294967295，其结果为 32 个 1 的字符串。

参数

Decimal value to convert

返回值

Binary string representation of$number

范例

Example #1decbin()例子

以上例程会输出：

1100
11010

参见

• bindec() 二进制转换为十进制
• decoct() 十进制转换为八进制
• dechex() 十进制转换为十六进制
• base_convert() 在任意进制之间转换数字
• printf() 输出格式化字符串,using%b,%032bor%064bas the format
• sprintf(),using%b,%032bor%064bas the format

To add leading zeros I prefer the following: 

A fast function to convert a binary string to a bit sequence 

Regarding trailing zeros, after test all the option mention here by others, i have performed my own tests regarding efficiency, here are the results:

results
0000100100001001000010010000100.... (output is echoed 1000 times)
Duracion 0.0134768486023 segundos
8
Duracion 0.00054407119751 segundos
00001001
Duracion 0.000833988189697 segundos
00001001
Thus the winner is 

Print as binary format with leading zeros into a variable in one simple statement. 

Another larger-than-31-bit function.
Works for very large numbers, but at the expense of perfect bit-precision as the size increases (I noticed rounding errors past 16 or so decimal places) so use with caution, and only when decbin() won't cut it.
function Dec2Bin($number) {
  while ($number >= 256) {
    $bytes[] = (($number / 256) - (floor($number / 256))) * 256;
    $number = floor($number / 256);
  }
  $bytes[] = $number;
  for ($i=0;$i

A little useful little function that returns a binary string with leading 0s:
function d2b($n) {
 return str_pad(decbin($n), 16, "0", STR_PAD_LEFT);
}
// example:
echo d2b(E_ALL);
echo d2b(E_ALL | E_STRICT);
echo d2b(0xAA55);
echo d2b(5);
Output:
0111011111111111
0111111111111111
1010101001010101
0000000000000101

This is my System:
You can convert a decimal number to a number system you want, like the binary system. 

Careful trying binary-wise tests with integers:
# FFFFFFFF
command: php -r 'print(decbin(4294967295)."\n");'
result: 11111111111111111111111111111111
# C3E9CAC8
command: php -r 'print(decbin(3286878920)."\n");'
result: 11000011111010011100101011001000
# regardless of specifying "(int)", using bitwise AND:
command: php -r 'print((int)(3286878920 & 4294967295)."\n");'
result: -1008088376 (int)
# now the expected result will happen (guess the performance impact)
command: php -r 'print(bindec(decbin((3286878920 & 4294967295)))."\n");'
result: 3286878920 (float)
additional note: if you "bitwise and" some random bits with a sequence of 1-bit of the same length, the expected result is the same "random bits sequence" unchanged. If you want to keep this in the integer world for faster comparisons, you risk messing your result for the signed integer size limitation. The maximum value you can use for the desired result is (7FFFFFFF -- or integer 2147483647), half of the maximum 'unsigned' integer 32-bit(platform-dependent) value.

I think this is the best function. Is almost endlessy (till 2^50 or something) 

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