What is &= and |=

Question

I was going through some VC++ code in a large code-base and came across this:

    if (nState & TOOL_TIPS_VISIBLE)
        nState &= ~TOOL_TIPS_VISI         


        

Answer 1

Its bitwise and or

in the first case the flag (bit) is turned off

nState &= ~TOOL_TIPS_VISIBLE

in the second case the flag is turned on

nState |= TOOL_TIPS_VISIBLE