Bits and Bytes in C

Bits and Bytes in C:

Bit:
- A bit is the smallest unit of data in a computer.
- It can store 0 or 1 (binary states).
- In C, data is ultimately stored and manipulated at the bit level.
Byte:
- A byte is composed of 8 bits.
- It is the basic unit of data storage in C (and most systems).
- The size of many data types in C (like int, char, etc.) is measured in bytes.
Size of Data Types (in bytes):
- char: 1 byte (8 bits).
- int: Typically 4 bytes (32 bits) on most systems.
- float: Typically 4 bytes.
- double: Typically 8 bytes.
- pointer: Typically 8 bytes on 64-bit systems, 4 bytes on 32-bit systems.
Use sizeof() to determine the size of any data type in your system:
```
printf("Size of int: %lu bytes\\\\n", sizeof(int));
```
How Data is Stored in Memory:
- Data is stored in binary format (0s and 1s).
- Each byte in memory is identified by a unique memory address.
- For example, a 32-bit int has 4 bytes (32 bits), which are stored consecutively in memory, starting from the least significant byte in little-endian systems or the most significant byte in big-endian systems.
Endianness:
- Little-Endian: Least significant byte is stored at the lowest memory address.
- Big-Endian: Most significant byte is stored at the lowest memory address.
Example:
```
int num = 0x12345678;
```
- In Little-Endian:
  - 78 (LSB) at lowest address.
- In Big-Endian:
  - 12 (MSB) at lowest address.
Bitwise Operations in C:
- AND (&): Used to clear bits.
- OR (|): Used to set bits.
- XOR (^): Used to toggle bits.
- NOT (~): Used to flip bits.
- Left Shift (<<): Shifts bits to the left (multiplies by 2).
- Right Shift (>>): Shifts bits to the right (divides by 2).
Example:
```
int x = 5;  // 00000101 in binary
int y = x << 1;  // Left shift: 00001010 (5 * 2 = 10)
```
Bit Masking:
- Used to manipulate specific bits in a byte or word.
- Example: Set the 3rd bit of a number.
```
x |= (1 << 2);  // Sets the 3rd bit of x to 1.
```