gmp_testbit

    (PHP 5 >= 5.3.0, PHP 7, PHP 8)

    gmp_testbit — Tests if a bit is set

    说明

    gmp_testbit(GMP|int|string $num, int $index): bool

    Tests if the specified bit is set.

    参数

    num

    GMP 对象或 int ，或数字string。

    index

    The bit to test

    返回值

    Returns true if the bit is set in num, otherwise false.

    错误／异常

    An E_WARNING level error is issued when index is less than zero, and false is returned.

    示例

    示例 #1 gmp_testbit() example

    <?php
    $n     = gmp_init("1000000");
    var_dump(gmp_testbit($n, 1));
    gmp_setbit($n, 1);
    var_dump(gmp_testbit($n, 1));
    ?>

    以上示例会输出：

    bool(false)
bool(true)

    参见

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    用户贡献的备注 1 note

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    bluej100@gmail
    17 years ago
    gmp_testbit will be very useful for my (over 64-bit) bitmask checking.

    In the meantime, I think these are the best replacements.

    Mostly full:

    <?php
    (gmp_scan1($a, $index) == $index)
    ?>

    Mostly empty:

    <?php
    (gmp_scan0($a, $index) != $index)
    ?>

    Still worst-case O(N), though.
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