Php manual bitwise operators

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In the duplicate, there's nothing related to the two's complement arithmetic, which is the essence of this question. I doubt it is an exact duplicate. In other words, try avoiding using the binary operators on strings :. Silver 6 years ago. Tbrendstrup 10 years ago.

Just learning Bitwise Shift Operators. It is true that if both the left-hand and right-hand parameters are strings, the bitwise operator will operate on the characters' ASCII values. However, a complement is necessary to complete this sentence. It is not irrelevant to point out that the decimal character's ASCII value have different binary values.

Well PHP uses the method "2's complement" to render negative binary numbers. If the left most bit is a 1 then the binary number is negative and you flip the bits and add 1. If it is 0 then it is positive and you don't have to do anything. So would be a positive 2. If it is , it is negative and you flip the bits to get Add 1 and you get which equals Anonymous 4 years ago.

Core Xii 5 years ago. Be very careful when XOR-ing strings! If one of the values is empty 0, '', null the result will also be empty! An integer XOR'd with zero results the original integer.

But a string XOR'd with an empty value results an empty value! My password hashing function was always returning the same hash Because I was XOR-ing it with a salt that was sometimes empty!

Adam 5 years ago. Be careful of order of operations. Another practical case Ketting 1 year ago. In addition to the basic assignment operator, there are "combined operators" for all of the binary arithmetic , array union and string operators that allow you to use a value in an expression and then set its value to the result of that expression. Note that the assignment copies the original variable to the new one assignment by value , so changes to one will not affect the other.

This may also have relevance if you need to copy something like a large array inside a tight loop. An exception to the usual assignment by value behaviour within PHP occurs with object s, which are assigned by reference. Objects may be explicitly copied via the clone keyword. Assignment by reference means that both variables end up pointing at the same data, and nothing is copied anywhere.

Operator precedence and associativity only determine how expressions are grouped, they do not specify an order of evaluation. PHP does not in the general case specify in which order an expression is evaluated and code that assumes a specific order of evaluation should be avoided, because the behavior can change between versions of PHP or depending on the surrounding code.

Example 2 Undefined order of evaluation. Arithmetic Operators ». Submit a Pull Request Report a Bug. Operator Precedence The precedence of an operator specifies how "tightly" it binds two expressions together.

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