std::string_view is a read-only view over a string, it doesn’t hold any data, it only holds a pointer to the first character of the
string and its length. std::string_view can offer better performance than std::string in several cases:
- no memory allocations are required during construction, it is cheap to pass them by value, no need to pass them by reference
- no heap allocation when passing a string literal to a
std::string_view function argument
-
substr operations over a std::string_view do not require memory allocation
When using std::string_view you shouldn’t however forget that:
- it’s a non-owning range, you should keep into consideration the liveness of the pointed range
- it doesn’t guarantee a null-terminated string like
std::string
This rule flags const std::string& function arguments, which can be safely replaced with std::string_view ones when
not relying on the null-termination character.
Note that, if you are calling substr on the parameter, you may have to modify your code to explicitly cast the result to
std::string.
Noncompliant code example
void fun(const std::string& name) { // Noncompliant, replace const std::string& by std::string_view
// ...
}
Compliant solution
void fun(std::string_view name) {
// ...
}
