# <istream>

**[<istream>](https://en.cppreference.com/w/cpp/header/istream)** defines `std::basic_istream` and `std::istream`, the base classes for input streams. It provides `operator>>` for formatted input, `get()`, `getline()`, and `read()` for unformatted input.

You rarely use this directly; instead you use concrete classes like `std::cin` or `std::ifstream` that inherit from it.

## Example

This example uses a string stream for formatted input parsing, extracting an integer, string, and floating-point value.

```cpp
// compile: g++ -std=c++11 -o istreamexample istreamexample.cpp
// run: ./istreamexample
// description: formatted input with operator>>

#include <istream>
#include <iostream>
#include <sstream>

int main() {
    std::istringstream iss("42 hello 3.14");
    
    int i;
    std::string s;
    double d;
    
    iss >> i >> s >> d;
    std::cout << "i=" << i << ", s=" << s << ", d=" << d << "\n";
    
    return 0;
}
```