# C++ noexcept

**[noexcept](https://en.cppreference.com/w/cpp/language/noexcept_spec)** is a specifier declaring that a function will not throw exceptions (or will terminate if it does). A `noexcept` function enables compiler optimizations and is required for strong exception safety guarantees in moves and swaps. Misusing `noexcept` on code that can actually throw results in `std::terminate`.

Use `noexcept` on move constructors, move assignment, swaps, and other operations that standard containers rely on to be nothrow.

## Example

This example shows noexcept enabling optimizations and required for move operations.

```cpp
// compile: g++ -o noexcept noexcept.cpp
// run: ./noexcept
// description: noexcept enables optimizations and satisfies container requirements

#include <iostream>
#include <vector>
#include <utility>

class SafeBuffer {
private:
    int* data;
    size_t size;
public:
    SafeBuffer(size_t n) : size(n), data(new int[n]) {}
    
    ~SafeBuffer() { delete[] data; }
    
    SafeBuffer(SafeBuffer&& other) noexcept
        : data(other.data), size(other.size) {
        other.data = nullptr;
    }
    
    SafeBuffer& operator=(SafeBuffer&& other) noexcept {
        delete[] data;
        data = other.data;
        size = other.size;
        other.data = nullptr;
        return *this;
    }
};

int main() {
    std::vector<SafeBuffer> v;
    v.push_back(SafeBuffer(100));  // move is noexcept, vector optimizes
    
    return 0;
}
```