C-style bit manipulation

A bit can be set using the bitwise OR operator (|).

// Bit x will be set
number |= 1LL << x;

Using std::bitset

set(x) or set(x,true) - sets bit at position x to 1.

std::bitset<5> num(std::string("01100"));
num.set(0);      // num is now 01101
num.set(2);      // num is still 01101
num.set(4,true); // num is now 11110