I read a book it stated that once b1 set to false by assignment operator the remaining will be false but why on line 2 i still can go to the other test?
In the second line your condition is (b1=false) | (b1=true). This is a boolean or operator. It requires that both conditions be evaluated. An or is true is either of its operands are true. Since in the second condition you set b1 to true, the result of the or is true.
I think you read about the conditional-AND (&&) and conditional-OR (||) operators from the book. Only Conditional-AND, Conditional-OR and Conditional-Assignment (? will evaluate the operands based on need (if further evaulation is needed to determinte the outcome).
The operators you mentioned in this snippet are Logical/Bitwise OR operator which evaluates all the operands before performing the operation.