<< stl

C++ bitset

# Initialization

  1. bitset<n> b: Initialize a bitset with length n and filled with 0.

  2. bitset<n> b(u): Initialize bitset b by unsigned long long u. If n exceeds the bits of unsigned long long (that is, exceeds 64), those high bits will be filled with 0.

  3. bitset<n> b(s, pos, m, zero, one): Initialize bitset b by string s, starting from pos, with length m. s can only contain zero an one.

    By default pos is 0, pos is std::string::npos, and zero/one are '0' and '1' respectively.

  4. bitset<n> b(cp, pos, m, zero, one): Similar to (3) but given a character array instead of std::string. If m is not given, cp must points to a C-style array, that is, the tailing \0 must exist.

# C++ bitset Non-modification Method
Method Interpretation
b.any() if any bit is 1
b.any() if all bits are 1
b.none() if all bits are 0
b.count() count number of 1
b.size() count total bits
b.test(pos) if position pos is 1
b[pos] Access position pos.
b.to_ulong()
b.to_ullong()		 return a unsigned long value
or unsigned long long value
b.to_string(zero, one) return a string. zero/one are 0/1 by default
# C++ bitset Modification Method
Method Interpretation
b.set(pos, v)
b.set()		 set pos to v, v=true by default.
If no pos given, set all to 1.
b.reset(pos)
b.reset()		 set pos to 0.
If not pos given, set all to 0.
os << b print b as 0/1 string.
is >> b read character 0/1 into b,
stop reading if the next character is not 0/1
or there is no enough space in b.