std::string_view (C++17)

In a Nutshell

A read-only string "view" that performs no copying or memory allocation. It holds only a pointer and a length, making it ideal for replacing const std::string& as a function parameter.

Header

#include <string_view>

Core API Cheat Sheet

Operation	Signature	Description
Construction	string_view(const CharT*, size_t)	Constructs from a pointer and length
Construction	string_view(const CharT*)	Constructs from a C-style string
Length	size()	Returns the number of characters
Empty Check	empty()	Checks if the view is empty
Element Access	operator[]	Accesses character at the specified position
Data Pointer	data()	Returns the underlying character array pointer
Remove Prefix	remove_prefix(size_t n)	Moves the start position forward by n
Remove Suffix	remove_suffix(size_t n)	Moves the end position backward by n
Substring	substr(pos, len)	Returns a substring view
Find	find(str)	Finds the position of a substring

Minimal Example

#include <string_view>
#include <iostream>

void print_sv(std::string_view sv) {
    std::cout << sv << std::endl;
}

int main() {
    // No copy, just a view
    std::string str = "Hello";
    std::string_view sv = str;

    print_sv("World"); // Implicit conversion from const char*
    print_sv(sv);      // Pass by view
}

Embedded Applicability: High

• Zero heap allocation. It has only two members (pointer and length), resulting in minimal memory overhead (typically 16 bytes).
• A TriviallyCopyable type, making it safe for use in interrupt contexts or for parsing DMA transfer buffers.
• Replaces const std::string& to avoid implicit std::string construction and the associated heap allocation.
• Caution: Be mindful of lifetimes. Never bind a temporary std::string to a std::string_view.

Compiler Support

GCC	Clang	MSVC
7.1	4.0	19.10

See Also

• cppreference: std::basic_string_view

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