To understand bit-wise operation, you must first understand hexadecimal number system. Computers only understand binary number system (base 2) because they only know 1's and 0's. The right most digit represents either a 0 or a 1, every subsequent digit to the left is an increment of the power of 2. So if the right most digit is 1, it represents one. If the next digit to the left is a 1, it represents 2. The next digit to the left represents 4, the next 8, the next 16 and so on. Therefore, the following decimal number can be translated to binary.
But binary numbers are not friendly to human because representing a typical number may require way too many digits. Hexadecimal system (base 16) is a good compromise because 16 is a power of 2 so it can be easily translated between binary and hexadecimal because it uses fewer digits. Every 4 binary bits can be combined to one hexadecimal digit. As the name implies a hexadecimal has 16 possible values (from 0 to 15). To represent the digit in a single character, we added letters (a-f) to represent 10-15. So the number 100 from the above example can be represented as:
To manipulate bits, you must understand the following bit-wise operators:
- "&" This is to do a bit-wise "AND" of two binary numbers. Typically, it allows you to "clear" a bit in a variable. For example:
- "|" This is to do a bit-wise "OR" of two binary numbers. Typically, it allows you to "set" a bit in a variable. For example:
- "~" This is to do a bit-wise "NEGATE" of a binary number. Typically, it allows you to negate a value to form a bit-mask for clearing a bit. For example:
- "^" This is to do a bit-wise "EXCLUSIVE-OR". Typically, it allows you to flip a bit. For example: