PHP gmp_scan0() function

As of my last update in September 2021, PHP’s GMP (GNU Multiple Precision) extension includes the gmp_scan0() function. This function is used to scan for the first zero bit in a GMP number, starting from the least significant bit (LSB) position.

Here’s the syntax of the gmp_scan0() function:

int gmp_scan0 ( GMP $num , int $start )

Parameters:

• $num: The GMP number to scan for zero bits.
• $start: The starting bit position for scanning. If provided, the function will start scanning from this bit position. If omitted, it starts scanning from the LSB position (bit 0).

Return value:

• The gmp_scan0() function returns the index of the first zero bit (counting from 0) found in the GMP number. If no zero bit is found, it returns -1.

Example:

$number = gmp_init('13'); // Binary: 1101

$zeroBitIndex = gmp_scan0($number);
echo "The index of the first zero bit is: " . $zeroBitIndex; // Output: The index of the first zero bit is: 0

In this example, the GMP number 13 (binary 1101) is scanned for the first zero bit, starting from the LSB position (bit 0). The first zero bit is found at index 0, and thus the function returns 0.

The gmp_scan0() function can be useful in various bitwise operations and can help in efficiently searching for specific bit patterns or performing bitwise manipulations on large integers.

As always, ensure that the GMP extension is enabled in your PHP configuration to use this function. Additionally, the availability of functions may change in newer PHP versions, so always refer to the PHP manual for the specific version you are using.