# <ostream>

**[<ostream>](https://en.cppreference.com/w/cpp/header/ostream)** defines `std::basic_ostream` and `std::ostream`, the base classes for output streams. It provides `operator<<` for formatted output, `put()`, `write()`, and `flush()`.

Most code uses `std::cout` or file output streams that inherit from this class.

## Example

This example writes formatted output to a generic ostream reference and explicitly flushes the stream.

```cpp
// compile: g++ -std=c++11 -o ostreamexample ostreamexample.cpp
// run: ./ostreamexample
// description: write to output stream

#include <ostream>
#include <iostream>

int main() {
    std::ostream& out = std::cout;
    
    out << "hello " << 42 << " " << 3.14 << "\n";
    out.flush();
    
    return 0;
}
```