# <iomanip>

**[<iomanip>](https://en.cppreference.com/w/cpp/header/iomanip)** provides stream manipulators for formatting output: `std::setw`, `std::setprecision`, `std::setfill`, `std::hex`, `std::oct`, `std::fixed`, `std::scientific`. They temporarily modify the stream state for a single output operation.

Most modern code prefers `std::format`, but `iomanip` remains useful for legacy streams.

## Example

This example applies various formatting manipulators to control decimal precision, hexadecimal output, and field width.

```cpp
// compile: g++ -std=c++11 -o iomanipexample iomanipexample.cpp
// run: ./iomanipexample
// description: stream formatting with manipulators

#include <iomanip>
#include <iostream>

int main() {
    double pi = 3.14159;
    int value = 255;
    
    std::cout << std::fixed << std::setprecision(2) << pi << "\n";
    std::cout << std::hex << value << "\n";
    std::cout << std::setw(10) << std::setfill('*') << 42 << "\n";
    
    return 0;
}
```