What is std::string_view in C++17?

Question

Accepted Answer

**std::string_view** — lightweight, non-owning reference to a string. Avoids copies.

```cpp
#include <string_view>

// Takes string_view — works with string, const char*, literals
std::string_view process(std::string_view sv) {
    return sv.substr(0, 5);
}

std::string s = "Hello, World!";
std::string_view sv1 = s;           // From string
std::string_view sv2 = "literal";    // From literal
std::string_view sv3 = s.data();     // From char*

std::cout << sv1.substr(0, 5);  // "Hello"
std::cout << sv1.size();        // 13
std::cout << sv1[0];            // H

// Comparison
if (sv1 == "Hello, World!") { /* ... */ }

// Convert back to string (when needed)
std::string str(sv1);
```

**Caveats:**
- Does not own the data — don't use after original string is destroyed.
- Cannot modify the string.
- No null terminator guarantee.

C++: What is std::string_view in C++17?