[Dayrion]

Код:

11111110111111111111111111111111

This is not the 8th bit.

If you try to "turn off" a specify bit, you can't do it with the OR logical operation because 1 OR 0 = 1 everytime.
You need to use AND logical operator with NOT.

PHP код:

main()
{
    new test_value = 0b1111111111; // there is 10, 1
    test_value &= ~(1 << 7); // 8-1
    printf("%b", test_value);
}