In C++, std::string_view is a non-owning view to a sequence of characters. It is part of the C++17 standard and is used to represent a read-only view of a std::string or a portion of a char array. This can be useful in scenarios where you don’t want to create a copy of the original string, but rather work with a view of it.

Features of std::string_view

• Non-owning: std::string_view does not own the underlying data, it simply refers to an existing string or character array.
• Lightweight: Because it’s just a view and doesn’t make a copy of the data, it’s lightweight and efficient.
• Null-terminated strings: It supports both null-terminated and non-null-terminated strings.

Example Usage

#include <iostream>
#include <string_view>

void printStringView(std::string_view sv) {
    std::cout << "Length: " << sv.length() << ", Data: " << sv << std::endl;
}

int main() {
    std::string str = "Hello, world!";
    std::string_view sv(str);

    printStringView(sv);  // Output: Length: 13, Data: Hello, world!
    
    // Substring
    std::string_view svSub = sv.substr(7, 5); // "world"
    printStringView(svSub);  // Output: Length: 5, Data: world

    return 0;
}

References

• C++ Reference - std::string_view