# <stdbit.h>

**[<stdbit.h>](https://en.cppreference.com/w/c/header/stdbit)** provides standard bit manipulation (C23): `stdc_popcount` (population count), `stdc_leading_zeros`, `stdc_trailing_zeros`, `stdc_rotl`, `stdc_rotr`. Previously you needed GCC builtins or platform-specific code.

Use it for portable bit operations without compiler-specific extensions.

## Example

This example demonstrates bit counting and rotation on integers.

```c
// compile: gcc -std=c2x -o stdbitexample stdbitexample.c
// run: ./stdbitexample
// description: bit manipulation functions

#include <stdbit.h>
#include <stdio.h>

int main() {
    unsigned int x = 0b11010011;
    
    printf("popcount(0b11010011) = %u\n", stdc_popcount(x));
    printf("leading zeros = %u\n", stdc_leading_zeros(x));
    printf("trailing zeros = %u\n", stdc_trailing_zeros(x));
    printf("rotl(x, 2) = 0x%x\n", stdc_rotl(x, 2));
    
    return 0;
}
```

## Common functions

**Bit counting**:
- `stdc_popcount(x)`: count set bits (population count)
- `stdc_popcount_uc(x)`, `stdc_popcount_us(x)`, `stdc_popcount_ui(x)`, `stdc_popcount_ul(x)`, `stdc_popcount_ull(x)`: type-specific variants

**Leading/trailing zeros**:
- `stdc_leading_zeros(x)`: count leading zero bits
- `stdc_trailing_zeros(x)`: count trailing zero bits
- Type-specific variants: `_uc`, `_us`, `_ui`, `_ul`, `_ull`

**Bit rotation**:
- `stdc_rotl(x, n)`: rotate left by n bits
- `stdc_rotr(x, n)`: rotate right by n bits
- Type-specific variants: `_uc`, `_us`, `_ui`, `_ul`, `_ull`

**Bit flag checks**:
- `stdc_has_single_bit(x)`: check if exactly one bit is set (is power of 2)