std::string_view (C++17)

In a nutshell

A read-only "view" of a string that copies nothing and allocates no memory — it holds just a pointer and a length, making it a good replacement for const std::string& as a function parameter.

Header file

#include <string_view>

Core API Cheat Sheet

Operation	Signature	Description
Construction	constexpr basic_string_view(const CharT* s, size_type count)	Constructs from a pointer and a length
Construction	constexpr basic_string_view(const CharT* s)	Constructs from a C string
Length	constexpr size_type size() const	Returns the number of characters
Empty check	constexpr bool empty() const	Checks whether the view is empty
Element access	constexpr const CharT& operator[](size_type pos) const	Accesses the character at the given position
Data pointer	constexpr const CharT* data() const	Returns a pointer to the underlying character array
Remove prefix	constexpr void remove_prefix(size_type n)	Advances the start position by n
Remove suffix	constexpr void remove_suffix(size_type n)	Pulls the end position back by n
Substring	constexpr basic_string_view substr(size_type pos = 0, size_type count = npos) const	Returns a substring view
Find	constexpr size_type find(basic_string_view v, size_type pos = 0) const	Finds the position of a substring

Minimal Example

#include <iostream>
#include <string_view>
// Standard: C++17

void print(std::string_view sv) {
    std::cout << sv << "\n";
}

int main() {
    std::string s = "hello";
    print(s);                    // accepts a std::string
    print("world");              // accepts a string literal
    std::string_view sv = s;
    sv.remove_prefix(1);         // now "ello"
    print(sv.substr(0, 2));      // outputs "el"
}

Embedded Suitability: High

• Zero heap allocation — just two members, a pointer and a length, so the memory overhead is tiny (typically 16 bytes)
• A TriviallyCopyable type, safe to use in interrupt contexts or when parsing DMA transfer buffers
• Replaces const std::string& to avoid the heap allocation caused by an implicit std::string construction
• Watch the lifetime: never bind a temporary std::string to a string_view

Compiler Support

GCC	Clang	MSVC
7.1	4.0	19.10

See Also

• cppreference: std::basic_string_view

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